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On the Relationship between the Winter Eurasian Teleconnection Pattern and the Following Summer Precipitation over China


doi: 10.1007/s00376-015-5195-3

  • The Eurasian teleconnection pattern (EU) is an important low-frequency pattern with well-known impacts on climate anomalies in Eurasia. The difference of low-level v-winds in several regions in the Eurasian mid-high latitudes is defined as the EU index (EUI V). In this study, the relationship between the winter EUI V and precipitation in the following summer over China is investigated. Results show that there is a significant positive (negative) correlation between the winter EUI V and the following summer precipitation over North China (the Yangtze River-Huaihe River basins). Meanwhile, an interdecadal variability exists in the interannual relationship, and the correlation has become significantly enhanced since the early 1980s. Thus, the proposed EUI V may have implications for the prediction of summer precipitation anomalies over China. In positive winter EUI V years, three cyclonic circulation anomalies are observed——over the Ural Mountains, the Okhotsk Sea, and the subtropical western North Pacific. That is, the Ural blocking and Okhotsk blocking are inactive, zonal circulation prevails in the mid-high latitudes, and the western Pacific subtropical high tends to be weaker and locates to the north of its normal position in the following summer. This leads to above-normal moisture penetrating into the northern part of East China, and significant positive (negative) precipitation anomalies over North China (the Yangtze River-Huaihe River basins), and vice versa. Further examination shows that the SST anomalies over the Northwest Pacific and subtropical central North Pacific may both contribute to the formation of EUI V-related circulation anomalies over the western North Pacific.
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  • Adler R.F., Coruthors, 2003: The Version-2 Global Precipitation Climatology Project (GPCP) monthly precipitation analysis (1979-present). J. Hydrometeor., 4, 1147- 1167.10.1175/1525-7541(2003)004<1147:TVGPCP>2.0.CO;228942e6d-8b3e-4278-b81c-e1bdaf53e50f53064fd724346e9bd7d78eab17550121http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2003JHyMe...4.1147Arefpaperuri:(6d3afea98ce646aaa127cb18ee109d24)http://adsabs.harvard.edu/abs/2003JHyMe...4.1147AThe Global Precipitation Climatology Project (GPCP) Version-2 Monthly Precipitation Analysis is described. This globally complete, monthly analysis of surface precipitation at 2.517 latitude 17 2.517 longitude resolution is available from January 1979 to the present. It is a merged analysis that incorporates precipitation estimates from low-orbit satellite microwave data, geosynchronous-orbit satellite infrared data, and surface rain gauge observations. The merging approach utilizes the higher accuracy of the low-orbit microwave observations to calibrate, or adjust, the more frequent geosynchronous infrared observations. The dataset is extended back into the premicrowave era (before mid-1987) by using infrared-only observations calibrated to the microwave-based analysis of the later years. The combined satellite-based product is adjusted by the rain gauge analysis. The dataset archive also contains the individual input fields, a combined satellite estimate, and error estimates for each field. This monthly analysis is the foundation for the GPCP suite of products, including those at finer temporal resolution. The 23-yr GPCP climatology is characterized, along with time and space variations of precipitation.
    Barnston A. G., R. E. Livezey, 1987: Classification, seasonality and persistence of low-frequency atmospheric circulation patterns. Mon. Wea. Rev., 115, 1083- 1126.29be75b7c6a781307ec830b0a6f33badhttp%3A%2F%2Ficesjms.oxfordjournals.org%2Fexternal-ref%3Faccess_num%3D10.1175%2F1520-0493%281987%291152.0.CO%3B2%26link_type%3DDOIhttp://icesjms.oxfordjournals.org/external-ref?access_num=10.1175/1520-0493(1987)1152.0.CO;2&amp;link_type=DOI
    Ding Y. H., 1994: Summer monsoon rainfall and its regional characteristics in China. Asian Monsoon. China Meteorological Press, 76- 83. (in Chinese)
    Enomoto T., 2004: Interannual variability of the Bonin high associated with the propagation of Rossby waves along the Asian jet. J. Meteor. Soc.Japan, 82, 1019- 1034.10.2151/jmsj.2004.1019ecf4888ad33f75476c33e2fdd06d4e8ahttp%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F110001803127http://ci.nii.ac.jp/naid/110001803127Interannual variability of the Ogasawara (Bonin) high in August is examined in relation to propagation of stationary Rossby waves along the Asian jet using monthly averages from the NCEP/NCAR reanalysis dataset for 52 years. The perturbation kinetic energy at 200 hPa is used as a measure of the activity of stationary Rossby waves along the Asian jet. Composite maps of five relatively wavy-jet years with close phases show an enhanced anticyclone over Japan. This anomalous ridge has a maximum amplitude at 250 hPa and extends throughout the troposphere with little zonal and slight northward tilts. Wave-activity and isentropic potential vorticity analyses clearly show that the ridge is created by the propagation of stationary Rossby waves to Japan. The anomalous ridge accompanies a positive temperature anomaly over Japan in the entire troposphere. A negative temperature anomaly to the east of Japan is also created in the lower troposphere by the northerly flow between the anomalous ridge and trough. By contrast, the equivalent-barotropic ridge over Japan is very weak in the zonal-jet years. Although Rossby waves are as strong as those in the wavy-jet years near the source, they are found to converge to the southeast of its source with little further downstream propagation. This contrast in the behaviour of Rossby waves is consistent with the intensity of the Asian jet to the east of 90掳E. The composite analysis suggests that the enhancement of a deep ridge near Japan is regulated by the intensity of the Asian jet. The composite analysis study conducted here emphasizes the importance of the propagation of stationary Rossby waves along the Asian jet for the late summer climate in northeastern Asia.
    Enomoto T., B. J. Hoskins, and Y. Matsuda, 2003: The formation mechanism of the Bonin high in August. Quart. J. Roy. Meteor. Soc., 129, 157- 178.10.1256/qj.01.211b4fd28b6511246b753d64625cdaa8af6http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1256%2Fqj.01.211%2Ffullhttp://onlinelibrary.wiley.com/doi/10.1256/qj.01.211/fullThe formation mechanism of the Bonin high in August ENOMOTO T. Quart. J. Roy. Meteor. Soc. 129, 157-178, 2003
    Gao H., Y. G. Wang, and J. H. He, 2006: Weakening significance of ENSO as a predictor of summer precipitation in China. Geophys. Res. Lett., 33, L09807.10.1029/2005GL025511c9813bf6f06a6ccd8e7d91e1ea9d15aehttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2005GL025511%2Fabstracthttp://onlinelibrary.wiley.com/doi/10.1029/2005GL025511/abstract[1] The interdecadal variation of the relationship between ENSO and summer precipitation in China has been examined based on observed monthly rainfall data and NOAA ERSST data from 1951 to 2003. Results show that the relation has weakened during the past two decades, and the significance of ENSO as a predictor has also decreased. An evident example is that before the late 1970s, when above-normal (below-normal) SST appears over the Nino-3 or Nino-4 regions in previous winters, more (less) summer rainfall will often be found in North China and south of Yangtze River valley, less (more) rainfall appears along the Huaihe River valley, and the Chinese Meiyu will be later (earlier). However, all of these conclusions should be adopted carefully after the 1980s because of the feeble relation between ENSO and summer precipitation in China. This weakening relationship has increased the difficulty of summer rainfall prediction in China.
    Gong D. Y., S. W. Wang, and J. H. Zhu, 2001: East Asian winter monsoon and Arctic oscillation. Geophys. Res. Lett., 28, 2073- 2076.10.1029/2000GL012311ee7a9a22559572d0b1be38c869554613http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2000GL012311%2Ffull%3FscrollTo%3Dreferenceshttp://onlinelibrary.wiley.com/doi/10.1029/2000GL012311/full?scrollTo=referencesIn this study, the connection between Arctic Oscillation (AO) and variability of East Asian winter monsoon is investigated. Two indices are chosen to describe the winter monsoon. One is the intensity of the Siberian High, defined as the average SLP over the center region, and the other is the temperature of eastern China, averaged over 76 surface stations. These are two tightly related components, correlate at -0.62 for period 1951-99. Temperature drops by 0.64 degrees Celsius in association with a one standard deviation increase in Siberian High intensity. It is found that there are significant out-of-phase relationships between the AO and the East Asian winter monsoon. The correlation coefficient between the AO and the Siberian High intensity index is -0.48 for period 1958-98. AO is also significantly correlated with the temperature of eastern China at 0.34. However, when the linear trend is removed, the correlation between AO and temperature is no longer significant. But the strong connection between the AO and Siberian High, and between the Siberian High and temperature are still significant. These results reveal that the AO influences the East Asian winter monsoon through the impact on the Siberian High. Negative phase of the AO is concurrent with a stronger East Asian Trough and an anomalous anticyclonic flow over Urals at the middle troposphere (500hPa). Both the AO and the Eurasian pattern play important roles in changes of the Siberian High and/or East Asian winter monsoon. They account for 13.0% and 36.0% of the variance in the Siberian High respectively.
    Guilderson T. P., D. P. Schrag, 1998: Abrupt shift in subsurface temperatures in the tropical Pacific associated with changes in El Niño. Science, 281, 240- 243.
    Guo Q. Y., 1983: The summer monsoon intensity index in East Asia and its variation. Acta Geographica Sinica, 3, 207- 217. (in Chinese)
    Horel J. D., 1981: A rotated principal component analysis of the interannual variability of the northern hemisphere 500 mb height field. Mon. Wea. Rev., 109, 2080- 2092.10.1175/1520-0493(1981)1092.0.CO;27b41015b-6112-4f74-a850-779d6469a65d1726290cf141f4c0f33043381b4be3c5http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1981MWRv..109.2080Hrefpaperuri:(7761e33936df838618948e334127fa34)http://adsabs.harvard.edu/abs/1981MWRv..109.2080HAbstract The principal components derived by Wallace and Gutzler (1981) from a 500 mb height data set are linearly transformed using the varimax method. Their data set consists of 45 winter months of National Meteorological Center analyses of Northern Hemisphere 500 mb height. The linear transformation (or rotation) of the principal components emphasizes the strongest relationships within the 500 mb height data set; hence, spatial patterns associated with the rotated principal components are simpler to interpret than the spatial patterns associated with the unrotated components. The teleconnection patterns identified by Wallace and Gutzler (1981) on the basis of the negative extrema approach closely resemble several of the spatial patterns of the rotated principal components. In order to show the seasonal dependence of the rotated principal components, an expanded data set consisting of 30 years of 500 mb height data is used. Most of the teleconnection patterns derived from the 90 winter month data set are esaws with the southernmost center of high correlation located in the subtropics. In some cases, additional centers of high correlation are located downstream of the two primary centers. The spatial patterns associated with the rotated principal components based on 90 summertime months are analogous to those for the wintertime months but are displaced northward along with the displacement of the time mean jet streams and storm-track regions.
    Hoskins B. J., D. J. Karoly, 1981: The steady linear response of a spherical atmosphere to thermal and orographic forcing. J. Atmos. Sci., 38, 1179- 1196.10.1175/1520-0469(1981)038<1179:TSLROA>2.0.CO;279fff4e3f8ece1da0529adaf44d4ea5dhttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1981JAtS...38.1179Hhttp://adsabs.harvard.edu/abs/1981JAtS...38.1179HMotivated by some results from barotropic models, a linearized steady-state five-layer baroclinic model is used to study the response of a spherical atmosphere to thermal and orographic forcing. At low levels the significant perturbations are confined to the neighborhood of the source and for midlatitude thermal forcing these perturbations are crucially dependent on the vertical distribution of the source. In the upper troposphere the sources generate wavetrains which are very similar to those given by barotropic models. For a low-latitude source, long wavelengths propagate strongly polewards as well as eastwards. Shorter wavelengths are trapped equatorward of the poleward flank of the jet, resulting in a split of the wave-trains at this latitude. Using reasonable dissipation magnitudes, the easiest way to produce an appreciable response in middle and high latitudes is by subtropical forcing. These results suggest an explanation for the shapes of patterns described in observational studies.The theory for waves propagating in a slowly varying medium is applied to Rossby waves propagating in a barotropic atmosphere. The slow variation of the medium is associated with the sphericity of the domain and the latitudinal structure of the zonal wind. Rays along which wave activity propagates, the speeds of propagation, and the amplitudes and phases along these rays are determined for a constant angular velocity basic flow as well as a more realistic jet flow. They agree well with the observational and numerical model results and give a simple interpretation of them.
    Hsu H. H., J. M. Wallace, 1985: Vertical structure of wintertime teleconnection patterns. J. Atmos. Sci., 42, 1693- 1710.10.1175/1520-0469(1985)042<1693:VSOWTP>2.0.CO;259b86ec07824dbc7586b21f8cef2a02ehttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1985JAtS...42.1693Hhttp://adsabs.harvard.edu/abs/1985JAtS...42.1693HABSTRACT Orthogonal rotated principal component analysis of the wintertime, Northern Hemisphere, 5-day mean sea level pressure field yielded five modes which are of some dynamical interest. One can be identified with the well-known North Atlantic Oscillation and another with the Pacific/North American pattern. Three of the other modes are highly baroclinic in the sense that their sea level pressure patterns and their associated 500 mb height patterns are different in shape and opposite in polarity over substantial areas. These more baroclinic patterns attain their largest amplitudes in the vicinity of the Himalayas and Rockies. Their spatial patterns evolve very differently in the lower and middle troposphere: the sea level pressure patterns exhibit a distinctive eastward and/or equatorward phase propagation, parallel to contours of surface elevation, along the northern and/or eastern side of the mountain ranges, while the corresponding 500 mb patterns evolve in a manner consistent with the concept of Rossby wave dispersion. It is hypothesized that the phase propagation of the sea level pressure pattern is due, in part, to the equivalent-beta effect responsible for the terrain slope.These highly baroclinic patterns appear to be associated with the low-temporal correlations between 1000 and 500 mb height and for the deep equatorward penetration of wintertime cold air outbreaks observed along the lee slopes of the major mountain ranges.
    Huang R. H., F. Y. Sun, 1992: Impacts of the tropical Western Pacific on the East Asian summer monsoon. J. Meteor. Soc.Japan, 70, 243- 256.1aaabaa5e72c71c10dbbd6497a52bf19http%3A%2F%2Fcat.inist.fr%2F%3FaModele%3DafficheN%26cpsidt%3D5464111http://cat.inist.fr/?aModele=afficheN&amp;cpsidt=5464111
    Huffman, G. J., Coruthors, 1997: The Global Precipitation Climatology Project (GPCP) combined precipitation dataset. Bull. Amer. Meteor. Soc., 78, 5- 20.10.1175/1520-0477(1997)078<0005:TGPCPG>2.0.CO;28d41c9f14c72ff096e849cfb2b6baab6http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1997BAMS...78....5Hhttp://adsabs.harvard.edu/abs/1997BAMS...78....5HABSTRACT The Global Precipitation Climatology Project (GPCP) has released the GPCP Version 1 Combined Precipitation Data Set, a global, monthly precipitation dataset covering the period July 1987 through December 1995. The primary product in the dataset is a merged analysis incorporating precipitation estimates from low-orbit-satellite microwave data, geosynchronous-orbit -satellite infrared data, and rain gauge observations. The dataset also contains the individual input fields, a combination of the microwave and infrared satellite estimates, and error estimates for each field. The data are provided on 2.5 deg x 2.5 deg latitude-longitude global grids. Preliminary analyses show general agreement with prior studies of global precipitation and extends prior studies of El Nino-Southern Oscillation precipitation patterns. At the regional scale there are systematic differences with standard climatologies.
    IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change,Boschung et al., Eds., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.
    Kalnay E., Coruthors, 1996: The NCEP/NCAR 40-year reanalysis project. Bull. Amer. Meteor. Soc., 77, 437- 471.f539a4fb-a013-4942-ac7e-7f15017eedac23d674534321ec5c56bf181fd85f5561http%3A%2F%2Fwww.bioone.org%2Fservlet%2Flinkout%3Fsuffix%3Di1536-1098-69-2-93-Kalnay1%26dbid%3D16%26doi%3D10.3959%252F1536-1098-69.2.93%26key%3D10.1175%252F1520-0477%281996%29077%3C0437%253ATNYRP%3E2.0.CO%253B2refpaperuri:(fe1c070047a030c900beb40441caee5a)/s?wd=paperuri%3A%28fe1c070047a030c900beb40441caee5a%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fwww.bioone.org%2Fservlet%2Flinkout%3Fsuffix%3Di1536-1098-69-2-93-Kalnay1%26dbid%3D16%26doi%3D10.3959%252F1536-1098-69.2.93%26key%3D10.1175%252F1520-0477%281996%29077%253C0437%253ATNYRP%253E2.0.CO%253B2&ie=utf-8
    Li C. Y., J. H. He, and J. H. Zhu, 2004: A review of decadal/interdecadal climate variation studies in China. Adv. Atmos. Sci.,21, 425-436, doi: 10.1007/BF02915569.10.1007/BF02915569bb9dae75651868a0548118f00b967340http%3A%2F%2Fwww.cnki.com.cn%2FArticle%2FCJFDTotal-DQJZ200403011.htmhttp://d.wanfangdata.com.cn/Periodical_dqkxjz-e200403012.aspxDecadal/interdecadal climate variability is an important element in the CLIVAR (Climate Variability and Predictability) and has received much attention in the world. Many studies in relation to interdecadal variation have also been completed by Chinese scientists in recent years. In this paper, an introduction in outline for interdecadal climate variation research in China is presented. The content includes the features of interdecadal climate variability in China, global warming and interdecadal temperature variability,the NAO (the North Atlantic Oscillation)/NPO (the North Pacific Oscillation) and interdecadal climate variation in China, the interdecadal variation of the East Asian monsoon, the interdecadal mode of SSTA (Sea Surface Temperature Anomaly) in the North Pacific and its climate impact, and abrupt change feature of the climate.
    Li J. P., Q. C. Zeng, 2002: A unified monsoon index. Geophys. Res. Lett.,29, 115-1-115-4, doi: 10.1029/2001GL013874.10.1029/2001GL013874577448a36ad1af8858c675bd2d140789http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2001GL013874%2Fabstracthttp://onlinelibrary.wiley.com/doi/10.1029/2001GL013874/abstract[1] There are several monsoon regions in the world. Some monsoon indices have been proposed to describe their variability, but a unified monsoon index suitable for all known monsoon regions has not yet been found. Here we present a unified dynamical index of monsoon, the dynamical normalized seasonality (DNS), and carry out an analysis of observation data over the past 40 years. The analysis shows that the DNS index can characterize the seasonal cycle and interannual variability of monsoons over different areas very well. The South Asia summer monsoon (SASM) sector (5°&ndash;22.5°N, 35°&ndash;97.5°E) is composed of two independent components, SASM1 (2.5°&ndash;20°N, 35°&ndash;70°E) and SASM2 (2.5°&ndash;20°N, 70°&ndash;110°E), with quite different relations with the monsoon rainfall over the South Asia. The African summer monsoon (ASM) is dominated by variability on the decadal time-scale, and its decadal abrupt decrease in 1967 may be an important cause of the persistent drought over the Sahel region. It is also found that there is a remarkable global correlation pattern between the South China Sea summer monsoon index (SCSSMI) and global precipitation during boreal summer.
    Li W. J., J. F. Chou, 1990: Relation between monthly mean circulation in the Northern Hemisphere and the summer precipitation in the middle and lower reaches of Changjiang River. Scientia Meteorologica Sinica, 10, 139- 146. (in Chinese)6c1b854d36172c3ee45d13780e96f51fhttp%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTotal-QXKX199002003.htmhttp://en.cnki.com.cn/Article_en/CJFDTotal-QXKX199002003.htmIn this paper, the effect of the monthly mean geopotential height departure at 500hPa on the precipitation in June-August in the middle and lower reaches of Chang.Tiang River and their relation are analysed by using the monthly height fields at 500hPa and the precipitation data during 1951-1984. We calculated the information area of mean height departure at 500hPa in view of forcasting precipitation in the middle and lower ranches of ChangJiang Piver. It is pointed out that the effect of mean height departure fields of the different period and area on the preeipitation in this area is diffrcnt. We also showed that the precipitation in this area is affected by EU (Eurasia) pattern circulation in Wir-ter and by EA-WP(East Asia-West Paci fic)pattenn circulation in summer The analysed results still show that the changes of height departure fields in the info r-mat ion area can represent the characteristic of the large scale changes of the true height departure fields to a certain degree.
    Liao Q. S., G. Y. Chen, and G. Z. Chen, 1981: Collection of Long Time Weather Forecast. China Meteorological Press, 103- 114. (in Chinese)
    Liu Y. Y., W. Chen, 2012: Variability of the Eurasian teleconnection pattern in the northern hemisphere winter and its influences on the climate in China. Chinese J. Atmos. Sci., 36, 423- 432. (in Chinese)10.1007/s11783-011-0280-zf6bfff58-c201-4d30-9cc9-fdf403070f7b52bfc9c41a9fa9cab79ea4ccd93dfefehttp%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-DQXK201202018.htmrefpaperuri:(9bab70eced2d2ffd3137c76a334a68b0)http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQXK201202018.htmBased on the monthly mean NCEP/NCAR reanalysis dataset and the surface air temperature and precipitation data from 160 China stations, the interannual variations of winter Eurasian teleconnection pattern (EU) and its possible influence on the climate in China are investigated. Wavelet analysis reveals that the significant periods of Eurasian teleconnection pattern index (EU index) are 2-4 years. The result suggests that the interannual variation of the EU is dominant, whereas the interdecadal component is weak. In a winter with positive EU phase, the East Asian westerly jet stream at 200 hPa tends to be enhanced and the East Asian trough at 500 hPa becomes stronger. In the meantime, there are the surface northerly anomalies in East Asia which lead to a cooling condition over there. The opposite situations tend to occur in a negative EU winter. Hence, during the boreal winter the cooling and less precipitation are likely to occur in most of eastern China associated with a positive phase of EU.
    Nitta T., 1987: Convective activities in the tropical western Pacific and their impact on the Northern Hemisphere summer circulation. J. Meteor. Soc. Japan., 65, 373- 390.10.1175/1520-0469(1987)044<1554:TAOPVT>2.0.CO;2b2b4f575-d4a6-46b0-8bf9-015cb29c3f2784fda2b986d0d4e7d94b9557e8a62161http%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F10013126166%2Frefpaperuri:(9b2fb89014c1d66010d07550d41568c2)http://ci.nii.ac.jp/naid/10013126166/Investigation, à l'aide de la couverture nuageuse vue par satellite, de la TSM (SST) et du géopotentiel, toutes données sur 7 ans (1978-84), des variations interannuelle et intrasaisonnière de l'activité convective en été, dans le Pacifique tropical ouest, ainsi que de l'impact sur la circulation dans l'hémisphère nord. Résultats principaux: lorsque la TSM est plus chaude de 1,0°C que la normale, les régions de convection active (typhons, dépressions tropicales) se déplacent vers le NE à partir d'une position normale près des Philippines jusqu'à 20 N, la couverture nuageuse dans les zones tempérée et équatoriale est fortement atténuée; une anomalie de haute p prédomine dans la zone tempérée (de la Chine est jusqu'au Pacifique nord); l'activité convective est très modulée par la variation intrasaisonnière; il existe des trains d'ondes de hauteur géopotentielle qui émanent de la source de chaleur qui s'étend des Philippines à l'Amérique du Nord; ils sont générés lorsque l'activité convective dans la mer des Philippines devient intense; en conclusion les ondes de Rossby sont générées par la source de chaleur associée à la variation intrasaisonnière; des anomalies de p en Asie de l'Est peuvent être considérées comme une conséquence de la génération de ces ondes
    Shi. N., andQ. G. Zhu, 1996: An abrupt change in the intensity of the east Asian summer monsoon index and its relationship with temperature and precipitation over east China. Int. J. Climatol., 16, 757- 764.
    Smith T. M., R. W. Reynolds, T. C. Peterson, and J. Lawrimore, 2008: Improvements to NOAA's historical merged land-ocean surface temperature analysis (1880-2006). J. Climate,21, 2283-2297, doi: 10.1175/2007JCLI2100.1.10.1175/BAMS-D-11-00241.19e0e8dd7-cc9f-481f-a557-9c9aee56af7ba871f494927b97ada299e482d296dab1http%3A%2F%2Fconnection.ebscohost.com%2Fc%2Farticles%2F83755233%2Fnoaas-merged-land-ocean-surface-temperature-analysisrefpaperuri:(dbc44c65ee1c9ace06b0727517ae2bee)http://connection.ebscohost.com/c/articles/83755233/noaas-merged-land-ocean-surface-temperature-analysisThis paper describes the new release of the Merged Land–Ocean Surface Temperature analysis (MLOST version 3.5), which is used in operational monitoring and climate assessment activities by the NOAA National Climatic Data Center. The primary motivation for the latest version is the inclusion of a new land dataset that has several major improvements, including a more elaborate approach for addressing changes in station location, instrumentation, and siting conditions. The new version is broadly consistent with previous global analyses, exhibiting a trend of 0.076°C decade 611 since 1901, 0.162°C decade 611 since 1979, and widespread warming in both time periods. In general, the new release exhibits only modest differences with its predecessor, the most obvious being very slightly more warming at the global scale (0.004°C decade 611 since 1901) and slightly different trend patterns over the terrestrial surface.
    Sun L. H., M. He, 2004: The relationship between summer precipitation in China and circulation anomaly in Euroasia and its application in precipitation prediction. Acta Meteorologica Sinica, 62, 355- 364. (in Chinese)10.1117/12.5280723892b30d4731d31b6e66682adf86c66dhttp%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTotal-QXXB200403010.htmhttp://en.cnki.com.cn/Article_en/CJFDTotal-QXXB200403010.htmCoupling action between 500 hPa height field and summer precipitation distribution in China has been analysed by SVD (Singular Value Decomposition) method. The following results are revealed. (1) The coupling between summer 500 hPa height field and precipitation distribution is associated with the teleconnection of atmospheric circulation. The first pattern of the coupling shows spatial distribution reflecting the characters of the EPA and EU pattern of atmospheric circulation and the precipitation distribution. High correlation areas are mostly associated with atmospheric activity centers. When blocking high is located in north eastern Asia, the western Pacific subtropical high is stronger than normal with its position to further south of the normal, the meridian circulation prevails in middle and high latitudes, the major rain belt is located in southern China, severe flooding appear more frequently in the Yangtze river basin. In the opposite situation, precipitation in the Yangtze River basin is below normal or even drought. (2) The precipitation time coefficient of the coupling action can at describe well drought and flooding distribution, especially at distinguishing rain belt patterns (north or south). This precipitation time coefficient may reflect decade variability of summer precipitation pattern in China. (3) The analysis to the coupling between the 500 hPa circulation characteristics in winter, spring seasons and the summer precipitation distribution shows that from previous winter present to summer, the coupling characteristics between 500 hPa height field and precipitation distribution have persistence. Previous circulation influences summer precipitation distribution through rhythm relationship and thermodynamic condition contrast between land and ocean. (4) With the results from SVD analysis and previous circulation anomaly, a forecast model for summer precipitation in China is established. The prediction experiment shows a certain capability.
    Sung M. K., G. H. Lim, W. T. Kwon, K. O. Boo, and J. S. Kug, 2009: Short-term variation of Eurasian pattern and its relation to winter weather over East Asia. Int. J. Climatol., 29, 771- 775.10.1002/joc.17745ea9836a57078eda5218da73be887716http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.1774%2Fpdfhttp://onlinelibrary.wiley.com/doi/10.1002/joc.1774/pdfNot Available
    Tao S. Y., L. X. Chen, 1987: A review of recent research on the East Asian summer monsoon in China. Review of Monsoon Meteorology,C. P. Chang and T. N. Krishnamurti, Eds., Oxford University Press, 353 pp.7a7cf2cfdb1d11184ad32b44ecf07d62http%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F10012388648http://ci.nii.ac.jp/naid/10012388648A review of recent research on the East Asian summer monsoon in China TAO S. Y. Monsoon Meteorology, 1987
    Wallace J. M., D. S. Gutzler, 1981: Teleconnections in the geopotential height field during the Northern Hemisphere winter. Mon. Wea. Rev., 109, 784- 812.3544b322a43213a44a5bb1db36c9aad9http%3A%2F%2Ficesjms.oxfordjournals.org%2Fexternal-ref%3Faccess_num%3D10.1175%2F1520-0493%281981%29109%3C0784%3ATITGHF%3E2.0.CO%3B2%26link_type%3DDOI/s?wd=paperuri%3A%280e55abb1142dfa51fadeb8554d09d495%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D1981MWRv..109..784W%26db_key%3DPHY%26link_type%3DABSTRACT&ie=utf-8
    Wang B., 1995: Interdecadal changes in El Niño onset in the last four decades. J Climate, 8, 267- 285.10.1175/1520-0442(1995)008<0267:ICIENO>2.0.CO;29af9dd38-2824-482e-a38c-40539f8ac9fe8ad9381e4a9776739a781669ae73cb3ehttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1995JCli....8..267Wrefpaperuri:(3e99bf01a233dac3571aa5f9e9d8e512)http://adsabs.harvard.edu/abs/1995JCli....8..267WAbstract The characteristics of the onset of the Pacific basin-wide warming have experienced notable changes since the late 1970s. The changes are caused by a concurrent change in the background state on which El Ni09o evolves. For the most significant warm episodes before the late 1970s (1957, 1965, and 1972), the atmospheric anomalies in the onset phase (November to December of the year preceding the El Ni09o) were characterized by a giant anomalous cyclone over east Australia whose eastward movement brought anomalous westerlies into the western equatorial Pacific, causing development of the basin-wide warming. Meanwhile, the trades in the southeastern Pacific (20°S–0°, 125°–95°W) relaxed back to their weakest stage, resulting in a South American coastal warming, which led the central Pacific warming by about three seasons. Conversely, in the warm episodes after the late 1970s (1982, 1986–87, and 1991), the onset phase was characterized by an anomalous cyclone over the Philippine Sea whose intensification established anomalous westerlies in the western equatorial Pacific. Concurrently, the trades were enhanced in the southeastern Pacific, so that the coastal warming off Ecuador occurred after the central Pacific warming. It is found that the atmospheric anomalies occurring in the onset phase are controlled by background SSTs that exhibit a significant secular variation. In the late 1970s, the tropical Pacific between 20°S and 20°N experienced an abrupt interdecadal warming, concurrent with a cooling in the extratropical North Pacific and South Pacific and a deepening of the Aleutian Low. The interdecadal change of the background state affected El Ni09o onset by altering the formation of the onset cyclone and equatorial westerly anomalies and through changing the trades in the southeast Pacific, which determine whether a South American coastal warming leads or follows the warming at the central equatorial Pacific.
    Wang H. J., 2001: The weakening of the Asian monsoon circulation after the end of 1970's. Adv. Atmos. Sci.,18, 376-386, doi: 10.1007/BF02919316.55186f36fb4d3628dc9d5fb9107f180bhttp%3A%2F%2Flink.springer.com%2F10.1007%2Fbf02919316/s?wd=paperuri%3A%28599517dce2b7f933daf31f27d3c1938a%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTotal-DQJZ200103004.htm&ie=utf-8
    Wang H. J., 2002: The instability of the East Asian summer monsoon-ENSO relations. Adv. Atmos. Sci.,19, 1-11, doi: 10.1007/s00376-002-0029-5.10.1007/s00376-002-0029-50b0b8196ff36c1ce99353d997ae7053bhttp%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-DQJZ200201000.htmhttp://en.cnki.com.cn/Article_en/CJFDTOTAL-DQJZ200201000.htmThe instability in the relation between the East Asian summer monsoon and the ENSO cycle in the long-term variation is found through this research. By instability, we mean that high inter-relation exists in some periods but low inter-relation may appear in some other periods.
    Wang H. J., S. P. He, 2012: Weakening relationship between East Asian winter monsoon and ENSO after mid-1970s. Chinese Science Bulletin, 57, 3535- 3540.10.1007/s11434-012-5285-x12e2dd29149405f915759bf891a55180http%3A%2F%2Flink.springer.com%2F10.1007%2Fs11434-012-5285-xhttp://www.cnki.com.cn/Article/CJFDTotal-JXTW201227002.htmThe East Asian winter monsoon(EAWM) is characterized by the frequent cold surges and associated closely with the Siberia High,East Asian Trough,and high-level westerly jet stream.The ENSO cycle can modulate the EAWM since it has co-variability with the sea surface temperature over the Indo-Western-Pacific which can tune the land-sea thermal contrast for the EAWM.This paper,by analyzing the EAWM,ENSO,and associated atmosphere-ocean variability,documents the weakening of the EAWMENSO relationship after the 1970s.The significant out-of-phase inter-relationship is found to be diminished after the 1970s.Further study in this work suggests that the weakened co-variability of the tropical Indo-Western-Pacific climate associated with ENSO after the 1970s is partly responsible for the weakened inter-relationship.Meanwhile,the reduced EAWM interannual variability and northward retreat of the EAWM-associated climate variability are favorable to the weakened ENSO-EAWM connection.
    Wang L., W. Chen, W. Zhou, J. C. L. Chan, D. Barriopedro, and R. H. Huang, 2010: Effect of the climate shift around mid 1970s on the relationship between wintertime Ural blocking circulation and East Asian climate. Int. J. Climatol., 30, 153- 158.10.1002/joc.18766cb4bd54-d121-4285-a7de-40066fee43fd90be1dd44eff9d5e0f60b9e6c882df17http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjoc.1876%2Ffullrefpaperuri:(c7826c675304790f71822d7d4b7eaf4b)http://onlinelibrary.wiley.com/doi/10.1002/joc.1876/fullAbstract Blocking variability over the Ural Mountain region in the boreal winter and its relationship with the East Asian winter climate is investigated. The climate shift around mid 1970s has been shown to exert a significant influence on the blocking pattern. In contrast with the years before 1976/1977, the Ural blocking signal after 1976/1977 is found to propagate less into the stratosphere and more eastward in the troposphere to East Asia, which therefore exerts more influence on the East Asian winter climate. This enhanced Ural blockingast Asian climate relationship amplifies the impact of Ural blocking on East Asia and, with the background of decreasing Ural blocking, contributes to the higher frequency of warm winters in this region. Further analyses suggest that the NAM-related stratospheric polar vortex strength and its modulation on the propagation of atmospheric stationary waves can account for this change, with the key area being located in the North Atlantic region. Copyright 2009 Royal Meteorological Society
    Wang N., Y. C. Zhang, 2015: Evolution of Eurasian teleconnection pattern and its relationship to climate anomalies in China. Climate Dyn.,44, 1017-1208, doi: 10.1007/s00382-014-2171-z.10.1007/s00382-014-2171-z979e1cf7c06f1038e0f98046a2dd0591http%3A%2F%2Flink.springer.com%2F10.1007%2Fs00382-014-2171-zhttp://link.springer.com/10.1007/s00382-014-2171-zThe Eurasian teleconnection pattern (EU) is a major mode of low-frequency variability in the Northern Hemisphere winter, with notable impacts on the temperature and precipitation anomalies in Eurasia region. To investigate the structure, life cycle and dynamical mechanisms of EU pattern, diagnostic analyses are conducted to clarify EU pattern evolution, with an emphasis on EU development and decay. In the developing stage, a geopotential height anomaly over North Atlantic emerges 602days before EU peak phase and other three geopotential height anomalies appear one by one in the following days. During this period, all geopotential height anomalies experience considerable growth and the four-center structure of EU pattern forms 202days before peak phase. The obvious wave train structure appears at 30002hPa. The EU pattern growth is driven by both relative vorticity advection and transient eddy fluxes. After the peak phase, the geopotential height anomaly over North Atlantic becomes weak as it decays earlier than other anomaly centers, which leads to the classic three-center structure of EU teleconnection pattern. The complete life cycle of EU pattern experience considerable growth and decay within 1002days. During the decaying stage, the horizontal divergence and the transient eddy fluxes play important roles. Additionally, the relationship of EU pattern to winter climate anomalies in China is also analyzed focusing on the decaying stage. The impact of EU pattern on temperature and precipitation in China are significant in 2–402days after EU peak phase and the distribution of temperature and precipitation anomaly has obvious regional differences.
    Wu R. G., J. L. Kinter III, and B. P. Kirtman, 2005: Discrepancy of interdecadal changes in the Asian region among the NCEP-NCAR reanalysis, objective analyses, and observations. J.Climate, 18, 3048- 3067. doi: 10.1175/JCLI3465.1.10.1175/JCLI3465.1840a699a5439b993dece01df8ac354bahttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2005JCli...18.3048Whttp://adsabs.harvard.edu/abs/2005JCli...18.3048WAbstract This study compares decadal means and interdecadal changes of surface and sea level pressures, tropospheric heights, and winds in the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis with objective analyses and observations. It is found that over Asia the NCEP–NCAR reanalysis pressures and heights are systematically lower than objective analyses and observations before the late 1970s. The magnitude of the differences changes from one decade to another and shows obvious seasonal dependence. The nonuniform spatial distribution of pressure and height differences is consistent with the discrepancy in lower-level meridional winds along the east Asian coast. The seasonal dependence of pressure differences affects the strength of the seasonal cycle over Asia. More importantly, large changes in the discrepancies from one decade to another lead to inconsistent interdecadal changes between the reanalysis and objective analyses or observations in the Asian region. While the reanalysis displays a large increase of pressure around 1977 and in the mid-1960s and an obvious decrease in the late 1950s, the changes are small in objective analyses and observations. Inconsistent interdecadal changes are also present in tropospheric heights and winds. The results indicate that the reanalysis may overestimate interdecadal changes over Asia. This calls for caution in utilizing the reanalysis output to study the interdecadal variability or the interannual variability without removal of interdecadal variations in the Asian region.
    Yang S., K.-M. Lau, and K.-M. Kim, 2002: Variations of the East Asian jet stream and Asian-Pacific-American winter climate anomalies. J.Climate, 15, 306- 325.10.1175/1520-0442(2002)015<0306:VOTEAJ>2.0.CO;2ee9f2be4-64de-4ebf-b871-28f619a5fb0960a4024a518ba1e3a1b378ac23df3d4ehttp%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F10013127551%2Frefpaperuri:(7d1aef2fb8c22e98233a0725c604d3a4)http://ci.nii.ac.jp/naid/10013127551/Variations of the East Asian jet stream and Asian-Pacific-American winter climate anomalies YANG S. J. Climate 15, 307-325, 2002
    Zhang Q. Y., S. Y. Tao, 1998: Influence of Asian mid-high latitude circulation on East Asian summer rainfall. Acta Meteorologica Sinica, 56, 199- 211. (in Chinese)10.11676/qxxb1998.019ab26d2ed-701f-4ead-83c2-7f50f43b9b7355841998210f8ae2de1a4e3592f80aacacb6e19ab34http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-QXXB802.006.htmrefpaperuri:(f5ea40ecd173652fb98bea64fa7ae997)/s?wd=paperuri%3A%28f5ea40ecd173652fb98bea64fa7ae997%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fen.cnki.com.cn%2Farticle_en%2Fcjfdtotal-qxxb802.006.htm&ie=utf-8In the paper, It had been pointed out that the main difference between Indian and East Asian summer monso on is the circulation of mid-high latitude had great influence on East Asian Summer monsoon. The study showed that during the flood years, the center of positive anomaly is around Okhot sksea, the negative center is around the mid-latitude and the another center of positive anomaly is around low-latitude over East-Asia, the positive and negative ano maly centers at 500 hPa level for med the anomaly wave train from low latitude to high latitude overeast Asia, At the same time there is another anomaly wave train from Ural mountains to Okhotsk sea in mid-high latitude, the positive anomaly center is around Uralmountains, the negative center is around Lake Baikal, the another positive center is around Okhot sksea. There is almost opposite wave train arrangement between flood and drought case of Changjiang river basin over Mid-high latitude and East Asia. The correlation between Okhot sksea and North Hemisphere had been made based on 500 hPa height data during 1951~1994 years. The status of Okhot sksea played anim-portant role in the forming of opposite wave trains for flood and drought case in Changjiang river basin. So, the pat terns of anomaly wave trains closely related to the status of Okhot sksea. Astrong persistent anticy clone remained over the Okhot sksea at 500 hPa level of ten causes summer flood events in Chang jiang river basin.
    Zhang Q. Y., S. Y. Tao, and L. T. Chen, 2003: The inter-annual variability of East Asian summer monsoon indices and its association with the pattern of general circulation over East Asia. Acta Meteorologica Sinica, 61, 559- 568. (in Chinese)10.1007/BF02948883bfc4a837c09dfa2e88d6de838f766fa6http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTotal-QXXB200305005.htmhttp://en.cnki.com.cn/Article_en/CJFDTotal-QXXB200305005.htmIn this paper it were discussed that the characteristics of convection and zonal wind over East Asia during summer. The East Asian summer monsoon index (EASMI) was defined using the difference of anomalous wind between the (10-20°N,100-150°E) and (25-35°N,100-150°E) at 850 hPa by the averaged Jun-Aug. The phenomena have been found that the opposite variation occurred between the latitude (25-35°N) and (10-20°N) over East Asia for the anomalous zonal wind at 850 hPa. There is a seesaw variation trend for the convective intensity between the tropical monsoon trough and Meiyu front over East Asia. The interannual rainfall patterns over Eastern China during summer related to the aspects of East Asian monsoon circulation. The rainfall over Yangtze River valley was abnormal while EASMI looked stronger (weaker). Further the relationships between the EASMI and anomalous geopotential height at 500 hPa have been analyzed. The"-+-"anomalous pattern occupied over East Asia at 500 hPa height field means that the cyclone circulation strengthened over East Asian monsoon trough region and that the subtropical anticyclone over Western Pacific shifted northward than the normal during summer. Meantime there was not the blocking situation over the Sea of Okhotsk. The "+-+" anomalous pattern occupied over East Asia at 500 hPa height field means that the East Asian monsoon circulation weakened and that the subtropical anticyclone over Western Pacific shifted southward than the normal during summer. The blocking situation occupied over the Sea of Okhotsk.
    Zhang Y. C., L. L. Guo, 2005: Relationship between the simulated East Asian westerly jet biases and seasonal evolution of rainbelt over eastern China. Chinese Science Bulletin, 50, 1503- 1508.10.1360/982004-3610a5b6c5f-69b8-4d24-9991-2e50d3689d3fmag1973820055014150386f4e235438b54fe905b8efff9cc17f6http%3A%2F%2Fd.wanfangdata.com.cn%2FPeriodical_kxtb-e200514017.aspxrefpaperuri:(ec609cb2ef6ad659854c9c68bcab3ee3)http://d.wanfangdata.com.cn/Periodical_kxtb-e200514017.aspx
    Zhao J. H., G. L. Feng, 2014: Reconstruction of conceptual prediction model for the three rainfall patterns in the summer of eastern China under global warming. Science China: Earth Sciences,57, 3047-3061, doi: 10.1007/s11430-014-4930-4.10.1007/s11430-014-4930-4105b1452ac9284c84b57734bc51bfd6ahttp%3A%2F%2Flink.springer.com%2F10.1007%2Fs11430-014-4930-4http://www.cnki.com.cn/Article/CJFDTotal-JDXG201412017.htmWith the influence of global warming,the global climate has undergone significant inter-decadal variation since the late 1970s.Although El Ni顝竜-Southern Oscillation(ENSO)has been the strongest signal for predicting global climate inter-annual variability,its relation with the summer rainfall in China has significantly changed,and its indicative function on the summer rainfall in China has weakened.This has led to a significant decrease in the accuracy rate of early conceptual prediction models for the Three Rainfall Patterns in the summer of eastern China.On the basis of the difference analysis of atmospheric circulation system configuration in summer,as well as the interaction of ocean and atmospheric in previous winter between two phases,i.e.before and after the significant global warming(1951 to 1978 and 1979 to 2012,respectively),we concluded that(1)Under different inter-decadal backgrounds,the atmospheric circulations that impacted the Three Rainfall Patterns in the summer of eastern China showed consistency,but in the latter phase of the global warming,the Western Pacific Subtropical High(WPSH)was on the strong side,the position of which was in the south,and the blocking high in the Eurasia mid-high latitudes was active,while the polar vortex extended to the south,and meridional circulation intensified.This circulation background may have been conducive to the increase of the circulation frequency of Patterns II and III,and the decrease of the circulation frequency of Pattern I,thus leading to more Patterns II and III and fewer Pattern I in the summer rainfall of eastern China.(2)In the former phase,the corresponding previous winter SST fields of different rainfall patterns showed visible differences.The impact of ENSO on North Pacific Oscillation(NPO)was great,and the identification ability of which on Patterns I and II of summer rainfall was effective.In the latter phase,this identification ability decreased,while the impact of ENSO on the Pacific/North American(PNA)teleconnection pattern increased,and the identification ability of the PNA on Patterns II and III also increased.Based on the new inter-decadal climate background,this study reconstructs the conceptual prediction model for the Three Rainfall Patterns in summer of eastern China by using the previous winter PNA and the Eurasian(EU)teleconnection indexes.The fitting effect was satisfying,though it is necessary to be further tested.
    Zuo X., Z. N. Xiao, 2013: Abnormal characteristics of Eurasian teleconnection in winter at pentad time scale and its impact on the weather in China. Meteorological Monthly, 39, 1096- 1102. (in Chinese)0a3e4b977f6d4c0803ee49d2e2ad8272http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-QXXX201309002.htmhttp://en.cnki.com.cn/Article_en/CJFDTOTAL-QXXX201309002.htmUsing the NCEP/NCAR global daily reanalysis data,this paper defined the winter pentad Eurasian teleconnection persistent anomaly,analyzed the characteristics of persistent abnormal process of EU pattern and discussed the corresponding atmospheric circulation and its impact on the winter weather in China.Statistical results show that:26 persistent abnormal processes occur in the 54 winters of 1957 ?2010.The positive persistent abnormal processes mainly occur in December,the 2nd to the 5th pentad of January,and the 4th pentad of February to the 1st pentad of March while the negative ones occur in the4th and 5th pentads of December,the first three pentads of January and the 3rd pentad of February to the1st pentad of March.Then the 200 hPa and 850 hPa geopotential height fields are selected to represent high and low atmospheric layers.Synthetic analysis shows that:during the processes of index anomalies,characteristics of strong EU pattern exists in both of the high and low atmospheric layers;and temperaturein most parts of China is influenced by EU index anomalies,showing significant difference.Precipitation presents significant difference in the middle and lower reaches of the Yellow River and Yangtze River,and parts of southeastern China.During positive abnormal processes,influenced by the strengthened Siberian high,northerly winds prevail in the lower troposphere over China with lower temperature and less rain-falls.The opposite situation tends to occur in negative processes.
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Manuscript received: 02 September 2015
Manuscript revised: 23 November 2015
Manuscript accepted: 08 December 2015
通讯作者: 陈斌, bchen63@163.com
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    沈阳化工大学材料科学与工程学院 沈阳 110142

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On the Relationship between the Winter Eurasian Teleconnection Pattern and the Following Summer Precipitation over China

  • 1. Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing 100081
  • 2. Department of Physical Science and Technology, Yangzhou University, Yangzhou 225002
  • 3. College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000
  • 4. Jiangsu Provincial Climate Center, Nanjing 210008

Abstract: The Eurasian teleconnection pattern (EU) is an important low-frequency pattern with well-known impacts on climate anomalies in Eurasia. The difference of low-level v-winds in several regions in the Eurasian mid-high latitudes is defined as the EU index (EUI V). In this study, the relationship between the winter EUI V and precipitation in the following summer over China is investigated. Results show that there is a significant positive (negative) correlation between the winter EUI V and the following summer precipitation over North China (the Yangtze River-Huaihe River basins). Meanwhile, an interdecadal variability exists in the interannual relationship, and the correlation has become significantly enhanced since the early 1980s. Thus, the proposed EUI V may have implications for the prediction of summer precipitation anomalies over China. In positive winter EUI V years, three cyclonic circulation anomalies are observed——over the Ural Mountains, the Okhotsk Sea, and the subtropical western North Pacific. That is, the Ural blocking and Okhotsk blocking are inactive, zonal circulation prevails in the mid-high latitudes, and the western Pacific subtropical high tends to be weaker and locates to the north of its normal position in the following summer. This leads to above-normal moisture penetrating into the northern part of East China, and significant positive (negative) precipitation anomalies over North China (the Yangtze River-Huaihe River basins), and vice versa. Further examination shows that the SST anomalies over the Northwest Pacific and subtropical central North Pacific may both contribute to the formation of EUI V-related circulation anomalies over the western North Pacific.

1. Introduction
  • Many studies have been conducted regarding the influences of monsoon circulation on the weather and climate of East Asia and China since the 20th century (Guo, 1983; Ding, 1994; Shi and Zhu, 1996; Wang, 2001; Li and Zeng, 2002; Zhang et al., 2003; Zhang and Guo, 2005). However, the weather and climate of China are not only affected by tropical and subtropical systems, but are also closely related to the extratropical atmospheric circulation in the NH (Zhang and Tao, 1998). The East Asian summer monsoon system clearly reveals the locations and intensities of the interactions between the cold air activities from the mid-high latitude systems and the warm and moist air flows brought by the subtropical system (Tao and Chen, 1987), which are the main reasons for the location and intensity variation of the summer rain belt in China.

    In fact, in an early study of the mid-high latitude circulations in the NH by (Wallace and Gutzler, 1981), it was suggested that there are five significant teleconnection patterns in the 500 hPa geopotential height field in the NH winter: the Pacific-North American (PNA) pattern, the eastern Atlantic pattern, the western Atlantic pattern, the western Pacific pattern, and the Eurasian (EU) pattern. (Barnston and Livezey, 1987) further confirmed the existence of the EU pattern based on rotated EOF analysis (REOF) of the monthly mean 700 hPa geopotential height field. (Hoskins and Karoly, 1981) demonstrated the great-circle theory to interpret the dynamics mechanism of the teleconnection patterns.

    Among these five significant patterns, the EU pattern is an important low-frequency pattern with well-known impacts on the atmospheric circulation and climate anomalies in the Eurasian region (Hsu and Wallace, 1985; Barnston and Livezey, 1987). (Li and Chou, 1990) demonstrated that the EU pattern is a major factor influencing the winter precipitation over the middle and lower reaches of the Yangtze River. In a study on the relationship between the Arctic Oscillation and the East Asian winter monsoon (EAWM) (Gong et al., 2001), it was determined that the EU pattern makes a significant contribution to the EAWM system, and its contribution to the Siberian high was found to be 36%. In addition, it was also pointed out that when the EU index is positive, the East Asian air temperature is lower. (Shi and Zhu, 1996) found that in cases of strong EAWM, China tends to be cold and dry in winter, and the atmospheric circulation is characterized by a strong western Pacific pattern and weak EU pattern. Several studies have pointed out that the daily variation of the EU pattern is responsible for climate anomalies over China and Korea, where abnormal cold/warm events are often dependent on the different phases of the EU pattern (Sung et al., 2009; Liu and Chen, 2012; Zuo and Xiao, 2013; Wang and Zhang, 2015). Positive EU phases are accompanied by strong northerly wind and a sudden descent of temperature in South China and Korea, while the probability distribution of cold/warm events is dependent on the phase of the EU pattern (Sung et al., 2009). (Wang et al., 2010) confirmed that the atmospheric circulation anomalies related to the Ural blocking (UB) are associated with the Eurasian wave train from west to east, and exhibit an enhancing influence on the East Asian winter climate anomalies.

    Moreover, the pre-winter EU pattern also has great impacts on the following summer climate anomalies over China. (Sun and He, 2004) used the SVD method to reveal the influences of pre-winter Eurasian circulation anomalies on the following summer precipitation over China. The pre-winter circulation of the Eurasian mid-high latitudes bears a very close coupling relationship with the following summer precipitation over China. It was also determined that the pre-winter circulation anomalies may influence the Eurasian summer circulation, as well as the precipitation anomalies over China, through a half-year rhythm relationship. Recently, when the "Conceptual Prediction Model for the Three Rainfall Patterns" in the summer of eastern China was reconstructed by (Zhao and Feng, 2014), the winter EU index (EUI V) was defined according to the difference of the 850 hPa v-wind anomalies in several key regions over the Eurasian mid-high latitudes. It was found that EUI V can be used effectively to judge whether or not the main following summer rain-belt would locate in northern China; namely, a north rain-belt pattern. However, the relationship between the winter EU pattern and the following summer precipitation has not been comprehensively examined. In addition, obvious interdecadal variability took place in the global oceans and atmospheric circulations in the late 1970s with global warming (Wang, 1995; Guilderson and Schrag, 1998; Li et al., 2004; IPCC, 2013), and the relationship between regional climates and their major factors of influence has changed (Wang, 2002; Gao et al., 2006; Wang and He, 2012). So, has the relationship between the winter EU pattern and the following summer precipitation undergone change?

    Understanding the impact of the EU pattern on climate anomalies over East Asia is important both for accurate weather forecasts and short-term climate forecasts. As mentioned above, the winter EU pattern can impact upon the concurrent weather and climate in East Asia. Plus, it also has "climate effects" on the subsequent climate over China. However, the relationship between the winter EU pattern and precipitation in the following summer over China is still not clear. The primary objectives of this study, therefore, are to discuss the relationship between the winter EU pattern and the following summer precipitation over China.

    The remainder of this paper is organized as follows: Section 2 describes the data and methods used in this study. The calculation, temporal evolution of different defined EUIs, and vertical structure of the EU pattern are shown in section 3. The relationship between the winter EUI V and the following summer precipitation over China is illustrated in section 4, followed in section 5 by a discussion of the summer atmospheric circulation and SST associated with the winter EUI V. A summary and conclusions are given in section 6.

2. Data and methodology
  • The main datasets employed in this study are: (2) monthly average precipitation data of 160 stations from the China Meteorological Administration for the period 1968-2013, and monthly global precipitation data——gridded at a resolution of 2.5°× 2.5°——from the GPCP for the period 1979-2013 (Huffman et al., 1997; Adler et al., 2003); (3) monthly mean circulation data, gridded at a resolution of 2.5°× 2.5°, from the NCEP-NCAR reanalysis (Kalnay et al., 1996) [note, however, that because the quality of the NCEP-NCAR reanalysis data over Asia may be low prior to 1968 (Yang et al., 2002; Wu et al., 2005), only the information since 1968 is analyzed in this study]; (3) SST data, gridded at a resolution of 2°× 2°, from ERSST.v3b (Smith et al., 2008); (4) the Niño3.4 SST index from the CPC.

    The time period analyzed in this study is 46 winters from 1967/1968 to 2012/2013. Wintertime means are constructed from the monthly means by averaging the data of December-January-February (DJF). Here, the winter of 1968 refers to the 1967/1968 winter. Springtime means are constructed from the monthly means by averaging the data of March-April-May (MAM), and summertime means are constructed from the monthly means by averaging the data of June-July-August (JJA).

    Correlation analysis, composite analysis, and linear regression are used to investigate the relationship between the winter EU pattern and the following summer precipitation over China.

    Figure 1.  The winter EUI (bars) and cumulative index (lines) from 1968 to 2013: (a) EUI$_WG$; (b) EUI$_BL$; (c) EUI$_V$.

3. Definition and climate characteristics of the EU index
  • In previous studies, the definitions and calculation methods of the EUI are different. In brief, they include two types. The first method uses the differences of the 500 hPa geopotential height anomaly field at a few key points (Wallace and Gutzler, 1981; Sung et al., 2009). The second method uses the corresponding time coefficients after the REOF on the Eurasian mainland height field of the NH troposphere (Horel, 1981; Hsu and Wallace, 1985; Barnston and Livezey, 1987). In addition, the difference of low-level (850 hPa) v-winds in several regions in the Eurasian mid-high latitudes is defined as the EU index (EUI V) by (Zhao and Feng, 2014). In order to compare the research results, the three types of definition methods proposed by (Wallace and Gutzler, 1981), (Barnston and Livezey, 1987) and (Zhao and Feng, 2014) are adopted to calculate the winter EUI from 1968 to 2013, and these calculation methods are shown as follows:

    The definition of the EUI introduced by (Wallace and Gutzler, 1981) is shown in Eq. (2), and denoted as EUI WG: $${EUI}_{WG}=-\dfrac{1}{4}Z^*_{55^{\circ}{N},20^{\circ}{E}}+\dfrac{1}{2}Z^*_{55^{\circ}{N},75^{\circ}{E}}- \dfrac{1}{4}Z^*_{40^{\circ}{N},145^{\circ}{E}} , (1)$$ where Z* represents the normalized seasonal average 500 hPa geopotential height anomaly.

    The EUI is defined by (Zhao and Feng, 2014) according to the significant area of the anomalies in the 850 hPa v-wind anomaly field in a north-type rain year over China. In Eq. (3), V' represents the 850 hPa v-wind anomaly: \begin{eqnarray} \label{eq2}{EUI}_{V}&=&V'_{50^{\circ}\hbox{-}60^{\circ}{N},45^{\circ}\hbox{-}55^{\circ}{E}} +V'_{55^{\circ}\hbox{-}65^{\circ}{N},130^{\circ}\hbox{-}140^{\circ}{E}}-\nonumber\\ &&V'_{35^{\circ}\hbox{-}45^{\circ}{N},10^{\circ}\hbox{-}20^{\circ}{E}}- V'_{55^{\circ}\hbox{-}70^{\circ}{N},95^{\circ}\hbox{-}110^{\circ}{E}}-\nonumber\\ &&V'_{50^{\circ}\hbox{-}65^{\circ}{N},155^{\circ}\hbox{-}165^{\circ}{E}} . (2)\end{eqnarray}A REOF decomposition was carried out by (Barnston and Livezey, 1987) on the 700 hPa geopotential height anomaly field in the extratropical NH (20°-90°N, 0°-360°). For unification, the seasonal average 500 hPa geopotential height anomaly fields are used here for the REOF decomposition, and the time coefficient corresponding to the sixth mode is defined as the EUI (denoted as EUI BL). The variance contribution of the sixth mode was 6.1%, and the accumulative variance contribution of the leading six modes reached 76.3%. The spatial distribution types of the leading five modes are similar to the PNA, North Atlantic Oscillation, and other teleconnection patterns. The mode with the first east-west wave trains is the sixth mode over Eurasia, which is similar to the EU pattern defined by (Wallace and Gutzler, 1981).

    Figure 1 shows the temporal evolution of the three winter EUIs during 1968-2013. The interannual variability of the three indices is relatively consistent. The correlation coefficient between EUI WG and EUI BL is 0.77, that between EUI WG and EUI V is 0.76, and that between EUI BL and EUI V is 0.72, all above the 99.9% confidence level. Through power spectrum analysis of the three indices (figure not presented), it is found that the quasi-three-year interannual variation period only exists in EUI BL, while the interdecadal variation period is not significant in the three indices.

    From the spatial distribution of the correlation coefficient between the three winter EUIs and the simultaneous 500 hPa geopotential height field (Fig. 2), it can be seen that all three indices show an obvious zonal teleconnection pattern of wave trains over Eurasia, of which the 500 hPa geopotential height anomaly fields in Western Europe, the Urals, and the coast of East Asia present significant negative-positive-negative correlation areas. The three activity centers of the winter EU pattern defined by (Wallace and Gutzler, 1981) are located at (55°N, 20°E), (55°N, 75°E) and (40°N, 145°E), respectively. The three activity centers are all located in the centers of the three high correlation regions in the EUI WG's correlation diagram (Fig. 2a). Moreover, there are another two positive correlation centers in eastern North America and the northern North Atlantic. In the EUI BL correlation diagram (Fig. 2b), there are two larger positive correlation areas in eastern North America and the northern North Atlantic, of which the positive correlation is very significant. However, the negative correlation area is smaller in Western Europe, where the significance of the negative correlation is weaker than the EUI WG. In the EUI V correlation diagram (Fig. 2c), there are two larger positive correlation areas in eastern North America and the northern North Atlantic, of which the positive correlation is very significant. The negative correlation area in Western Europe is larger and more significant than the EUI BL. The spatiotemporal characteristics of the three winter EUIs are highly consistent, and the EUI V shows the best relationship with the following summer precipitation over China among the three indexes from our calculation and analysis. Therefore, we choose the EUI V to analyze the relationship between the winter EU pattern and the following summer precipitation over China.

    Figure 2.  Correlation between the EUI and 500 hPa height field (20$^\circ$-90$^\circ$N, 0$^\circ$-360$^\circ$) in winter (DJF-averaged) from 1968 to 2013: (a) EUI$_WG$; (b)EUI$_BL$; (c) EUI$_V$. The shading from light to dark exceed the 95%, 99% and 99.9% confidence level, respectively. The contour interval is 0.2. The black dots are the three activity centers of the EU teleconnection pattern defined by Wallace and Gutzler (1981).

    Figure 3.  Correlation between the winter EUI$_V$ and the following summer (JJA-averaged) precipitation over China during (a) 1968-2013 and (b) 1981-2013. The black dots indicate the 95% confidence level.

    Figure 4.  21-year moving correlation between the EUI$_V$ and (a) $R_NC$ and (b) $R_JH$. The solid (dotted) line in (b) indicates the 95% (90%) confidence level.

    Figure 5.  The winter EUI$_V$ and "Three Rainfall Patterns" in the summer of eastern China from 1981 to 2013. The black (green) dotted line indicates EUI$_V$ greater than 2 (lesser than $-2$).

4. Winter EU pattern and summer precipitation over China
  • Figure 3 shows the distributions of the correlation coefficient between the EUI V and the following summer precipitation over China. There is a positive correlation in North China and a negative correlation in the Yangtze River-Huaihe River basins during 1968-2013 (Fig. 3a). Plus, the areas and stations above the 95% confidence level increase significantly during 1981-2013 (Fig. 3b) compared with during 1968-2013. According to Fig. 3b, two areas with a high density of stations above the 95% confidence level are selected. They are: eastern Xinjiang-western North China [hereinafter referred to simply as "North China"; (37°-47°N, 85°-110°E); 14 stations], and the Yangtze River-Huaihe River basins [(30°-34°N, 110°-125°E); 15 stations]. The area-averaged summer precipitation of the above two regions is represented by R NC and R YH, respectively. EUI V has a weak positive correlation (correlation coefficient of 0.18) with R NC, and a weak negative correlation (-0.10) with R YH during 1968-81. Whereas, EUI V has a significant positive correlation (0.42, exceeding the 99% confidence level) with R NC, and a significant negative correlation (-0.56, exceeding the 99.9% confidence level) with R YH during 1981-2013. To further confirm that the relationship between EUI V and summer precipitation has changed, Fig. 4 shows the 21-year moving correlation between the R NC, R YH, and EUI V. The EUI V and R NC show positive correlation, with the correlation slowly weakening after the mid-1980s, and strengthening recently (Fig. 4a). The correlation coefficient between the EUI V and R YH is relatively weak before the early 1980s, but it increases significantly after the mid-1980s (Fig. 4b).

    In the early 1980s, (Liao et al., 1981) classified the summer rain-belt of eastern China into three patterns ("Three Rainfall Patterns"), which are respectively described as follows: Pattern I is the northern pattern, of which the main rain-belt is located in the Yellow River basin and the region to the north; Pattern II is the central pattern, of which the main rain-belt is located between the Yellow River and Yangtze River; and Pattern III is the southern pattern, of which the main rain-belt is located in the Yangtze River basin or regions south of the Yangtze River. Figure 5 shows the relationship between the winter EUI V and the "Three Rainfall Patterns" in the summer of eastern China during 1981-2013. There are nine years in which the EUI V is greater than 2. With the exception of 2000 and 2002, all of the other seven years belong to Pattern I. Also, there are 17 years with an EUI V less than 0, and only one year belongs to Pattern I (1994). There are nine years for which the EUI V is less than -2, all of which are Pattern II or III, and none is Pattern I. Generally speaking, the EUI V could be used to effectively predict Pattern I years. The years for which the EUI V is greater than 2 (1981, 1985, 1988, 1992, 1995, 2000, 2002, 2004, 2012) and less than -2 (1982, 1989, 1991, 1996, 1997, 1998, 2003, 2007, 2008) are selected for composite analysis.

    Figure 6 shows the composite anomalies of precipitation in summer for + EUI V and - EUI V years, and their difference. For the + EUI V composite, a "plus-minus-plus-minus-plus" anomaly wave train is apparent from eastern Kazakhstan-western Xinjiang, northeastern Xinjiang-western Mongolia, and North China and the Yangtze River-Huaihe River basins to the Philippine Sea basin, of which the anomaly is significantly positive in North China, but significantly negative in the Yangtze-Huaihe River basin (Fig. 6a). For the - EUI V composite, a "minus-plus-minus-plus-minus" anomaly wave train is apparent from eastern Kazakhstan-western Xinjiang, western Inner Mongolia, and North China and the Yangtze River-Huaihe River basins to the Philippine Sea basin. Significantly positive anomalies are present in the Yangtze-Huaihe River basin (Fig. 6b). From the difference distribution between + EUI V and - EUI V years, the differences among the above five areas are very significant. Therefore, the winter EU pattern has an extra-seasonal connection with the following summer precipitation in China and the surrounding areas.

5. Summer atmospheric circulation and SST anomalies in association with the winter EUI V
  • To explain the above-mentioned relationships between the winter EUI V and the following summer precipitation anomalies, we first show the anomalies of geopotential height at 500 hPa and winds at 850 hPa in the summer, obtained as regression upon the winter EUI V (Fig. 7). Significantly negative geopotential height (Fig. 7a) and cyclonic circulation (Fig. 7b) anomalies exist over the Ural Mountains, Okhotsk Sea and the subtropical western North Pacific in the following summer. That is, in positive winter EUI V years, the UB and Okhotsk blocking (OB) are inactive, zonal circulation prevails in the mid-high latitudes, and the western Pacific subtropical high (WPSH) tends to be weaker and locates to the north of its normal position in the following summer. This leads to above-normal moisture penetrating into the northern part of East China. As a result, there are significant positive (negative) precipitation anomalies over North China (the Yangtze River-Huaihe River basins). In negative winter EUI V years, the UB and OB are active, meridional circulation prevails in the mid-high latitudes, and the WPSH tends to be stronger and locates to the south of its normal position in the following summer. As a result, there are significant positive precipitation anomalies over the Yangtze River-Huaihe River basins. These results are apparent via composite anomalies of 500 hPa geopotential height and 850 hPa wind in summer for winter + EUI V and - EUI V years, and their differences (figure not presented).

    Figure 6.  Composite of the following summer (JJA-averaged) precipitation anomaly percentage in East Asia under the (a) positive and (b) negative winter EUI$_V$, and the (c) composite difference between (a) and (b). The black dots indicate the 95% confidence level.

    Figure 7.  Anomalies of the following summer (JJA-averaged) (a) 500 hPa geopotential height (gpm) and (b) 850 hPa winds (m s$^-1$) regressed upon the winter EUI$_V$. The dark and light shading in (a) indicates that the anomalies are significantly different from zero at the 5% and 10% level, respectively. The dark and light shading in (b) indicates that the $u$-wind anomalies are significant at the 95% and 90% confidence level, respectively. The contour interval in (a) is 2 gpm.

    Figure 8.  Correlation between the DJF EUI$_V$ and (a) DJF SST, (b) MAM SST, and (c) JJA SST during 1981-2013. The dark and light shading indicates the 95% and 90% confidence level, respectively. And the solid (dotted) lines indicate the positive (negative) values. The contour interval is 0.1.

    Figure 9.  Anomalies of the following summer 850 hPa winds (m s$^-1$) regressed upon the MAM (a) $-1.0\times$ Niño3.4 and (b) West Pacific SST zonal difference index (WPZDI) during 1981-2013. The dark and light shading indicates that the $u$-wind anomalies are significant at the 95% and 90% confidence level, respectively.

    To help explain the summer circulation anomalies in association with the winter EUI V, the correlations between the winter EUI V and SST are shown in Fig. 8. There are significant negative (weak positive) correlations in the western North Pacific and subtropical central North Pacific (western Pacific) between the DJF EUI V and DJF SST (Fig. 8a). Furthermore, the correlation distribution is very much like a La Niña pattern. The correlation between the DJF EUI V and MAM SST (Fig. 8b) is similar to that of Fig. 8a, but there is a significant positive correlation in the western Pacific warm pool (WPWP) region, and the negative correlations in the western North Pacific become more significant. We define the SST anomaly (SSTA) difference in the MAM WPWP region (5°-20°N, 115°-130°E) and northwestern North Pacific (45°-55°N, 150°E-165°W) as the West Pacific SST zonal difference index (WPZDI). The correlation coefficient between the EUI V and WPZDI is 0.55, exceeding the 99% confidence level, and the correlation between the DJF EUI V and JJA SST (Fig. 8c) is insignificant.

    We further discuss the atmospheric circulation anomalies in association with the MAM SSTA. Figure 9 displays the JJA 850 hPa wind anomalies obtained by regression on the MAM Niño3.4 (multiplied by -1.0) (Fig. 9a) and WPZDI (Fig. 9b). A significantly cyclonic circulation anomaly is observed to control the subtropical western North Pacific, and an anticyclonic circulation anomaly exists over the Japanese islands and surrounding ocean (Fig. 9a). That is, in negative MAM Niño3.4 years (like La Niña years), the WPSH tends to be weaker and locates to the north of its normal position in the following summer. From the MAM WPZDI-related circulation anomalies (Fig. 9b), a cyclonic circulation anomaly is also observed to control the subtropical western North Pacific, and an anticyclonic circulation anomaly exists over the Japanese islands and surrounding ocean. Also, these circulation anomalies are very similar to the EUI V-related circulation anomalies (Fig. 7b). Therefore, SSTAs over the northwestern Pacific and subtropical central North Pacific may both contribute to the formation of EUI V-related circulation anomalies over the western North Pacific.

6. Discussion and conclusion
  • This paper examines the relationship between the winter EU pattern and the following summer precipitation over China using NCEP-NCAR, GPCP, and Chinese 160-station data for the period 1968-2013. The difference of low-level (850 hPa) v-winds in several regions in the Eurasian mid-high latitudes is defined as the EUI V by (Zhao and Feng, 2014). The results show that there is a significant positive (negative) correlation between the winter EUI V and the following summer precipitation over North China (the Yangtze River-Huaihe River basins). Meanwhile, an interdecadal variability exists in the interannual relationship, and the correlation has become significantly enhanced since the early 1980s. Thus, the proposed EUI V may have implications for the prediction of summer precipitation anomalies in the above regions.

    In positive winter EUI V years, the UB and OB are inactive, zonal circulation prevails in the mid-high latitudes, and the WPSH tends to be weaker and locates to the north of its normal position in the following summer. This leads to above-normal moisture penetrating into the northern part of East China. As a result, there are significant positive (negative) precipitation anomalies over North China (the Yangtze River-Huaihe River basins), and vice versa. Our present study shows that the winter EU pattern bears a close association with the following summer precipitation over China via key components of the East Asian summer monsoon system, such as the UB, OB and WPSH. Previous studies have demonstrated that atmospheric internal dynamic processes, including the Pacific-Japan or East Asia-Pacific wave train from the tropics (Nitta, 1987; Huang and Sun, 1992) and the "silk road" wave train from the mid-high latitudes in the NH (Enomoto et al., 2003; Enomoto, 2004), can exert substantial influence the interannual variability of WPSH. Further examination shows that the SSTA over the northwestern Pacific and subtropical central North Pacific may both contribute to the formation of EUI V-related circulation anomalies over the western North Pacific. Hence, the EUI V could be used as an effective predictor of summer precipitation anomalies in North China and the Yangtze River-Huaihe River basins. However, the extra-seasonal mechanism of influence of the winter EU on the following summer precipitation over China requires further study.

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