Allen R. J., S. C. Sherwood, 2011: The impact of natural versus anthropogenic aerosols on atmospheric circulation in the Community Atmosphere Model. Climate Dyn., 36, 1959- 1978. |
Bjerknes J., 1969: Atmospheric teleconnections from the Equatorial Pacific. Mon. Wea. Rev., 97, 163- 172.10.1175/1520-0493(1969)097<0163:ATFTEP>2.3.CO;29f0298dd45e510c14c05703bfaea0d37http%3A%2F%2Fwww.rand.org%2Fpubs%2Fpapers%2FP3882.htmlhttp://www.rand.org/pubs/papers/P3882.htmlAbstract The “high index” response of the northeast Pacific westerlies to big positive anomalies of equatorial sea temperature, observed in the winter of 1957–58, has been found to repeat during the major equatorial sea temperature maxima in the winters of 1963–64 and 1965–66. The 1963 positive temperature anomaly started early enough to exert the analogous effect on the atmosphere of the south Indian Ocean during its winter season. The maxima of the sea temperature in the eastern and central equatorial Pacific occur as a result of anomalous weakening of the trade winds of the Southern Hemisphere with inherent weakening of the equatorial upwelling. These anomalies are shown to be closely tied to the “Southern Oscillation” of Sir Gilbert Walker. |
Davis S. M., K. H. Rosenlof, 2012: A multidiagnostic intercomparison of tropical-width time series using reanalyses and satellite observations. J.Climate, 25, 1061- 1078.10.1175/JCLI-D-11-00127.124f05a7c1dfc955811c2d0ebcc43df09http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2012JCli...25.1061Dhttp://adsabs.harvard.edu/abs/2012JCli...25.1061DNot Available |
Deser C., A. S. Phillips, and M. A. Alexander, 2010: Twentieth century tropical sea surface temperature trends revisited. Geophys. Res. Lett., 37,L10701, doi: 10.1029/2010GL043321.10.1029/2010GL0433219c720851c7e29b64007ba4fd5737312bhttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2010GL043321%2Ffullhttp://onlinelibrary.wiley.com/doi/10.1029/2010GL043321/full[1] This study compares the global distribution of 20th century SST and marine air temperature trends from a wide variety of data sets including un-interpolated archives as well as globally-complete reconstructions. Apart from the eastern equatorial Pacific, all datasets show consistency in their statistically significant trends, with warming everywhere except the far northwestern Atlantic; the largest warming trends are found in the middle latitudes of both hemispheres. Two of the SST reconstructions exhibit statistically significant cooling trends over the eastern equatorial Pacific, in disagreement with the un-interpolated SST and marine air temperature datasets which show statistically significant warming in this region. Twentieth century trends in tropical marine cloudiness, precipitation and SLP from independent data sets provide physically consistent evidence for a reduction in the strength of the atmospheric Walker Circulation accompanied by an eastward shift of deep convection from the western to the central equatorial Pacific. |
Feng R., J. P. Li, and J. C. Wang, 2011: The principal modes of variability of the boreal summer Hadley circulation and their variations. Chinese Journal of Atmospheric Sciences, 35, 201- 206. (in Chinese)10.3724/SP.J.1146.2006.010859eaa61afe225a17a5d4662b46f3eed03http%3A%2F%2Fen.cnki.com.cn%2FArticle_en%2FCJFDTOTAL-DQXK201102003.htmhttp://en.cnki.com.cn/Article_en/CJFDTOTAL-DQXK201102003.htmThe principal modes of variability of the boreal summer(JJA) Hadley circulation(HC) and their variations during 1948-2007 are investigated.The results show that the year-to-year variability of the JJA HC is dominated by two asymmetric modes,centered respectively in the Northern Hemisphere(referred to as the AMN) and Southern Hemisphere(referred to as the AMS) as well as a quasi-symmetric mode(QSM) about the equator.The regime change of the JJA HC is revealed by the trends of the time series of AMN and AMS.It shows that the winter hemispheric HC has changed from one regime with strong northern part and weak southern part before the 1970s to the opposite regime with weak northern part and strong southern part since the 1970s.The variability of the JJA HC mentioned above can be explained by strong warming trends in the sea surface temperature(SST) over the equatorial Indian Ocean-western Pacific warm pool and the tropical Atlantic as well as the significant decreasing and increasing trends of the large-scale meridional SST gradients respectively in the Northern Hemisphere and the Southern Hemisphere over the tropical Atlantic and the Indian Ocean.The high-frequency interannual variability of the JJA HC,however,is mainly featured by the QSM,and highly correlated with the sea surface temperature over the eastern tropical Pacific Ocean and with the Nio3.4 index,implying that ENSO influence is mainly on high-frequency interannual time scale.Further study about the regime change of the HC reveals that the weakening of the cross-equatorial part of the HC is highly connected with the weakening of the meridional circulations over the tropical monsoon regions of the Eastern Hemisphere.The correlation and composite analyses show that the summer monsoon over the South China Sea,the eastern part of South Asia,and West Africa are significantly influenced by the regional meridional circulations,hence,the weakening trends of all those monsoons may be affected by the weakening of the cross-equatorial circulation during the regime change of the JJA HC.Nevertheless,the summer monsoon over the western part of South Asia does not show any noticeable trend or close connection with the regional meridional circulation.Thus,the result in this paper confirms the rationality of the division of the South Asia summer monsoon region into the east and west parts by Li and Zeng(2002). |
Frierson D. M. W., J. Lu, and G. Chen, 2007: Width of the Hadley cell in simple and comprehensive general circulation models. Geophys. Res. Lett., 34,L18804, doi: 10.1029/2007 GL031115.10.1029/2007GL031115d5d62696fe566a0d8c259911db5a3980http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2007GL031115%2Ffullhttp://onlinelibrary.wiley.com/doi/10.1029/2007GL031115/fullABSTRACT The width of the Hadley cell is studied over a wide range of climate regimes using both simple and comprehensive atmospheric general circulation models. Aquaplanet, fixed sea surface temperature lower boundary conditions are used in both models to study the response of the Hadley cell width to changes in both global mean temperature and pole-to-equator temperature gradient. The primary sensitivity of both models is a large expansion of the Hadley cell with increased mean temperature. The models also exhibit a smaller increase in width with temperature gradient. The Hadley cell widths agree well with a scaling theory by Held which assumes that the width is determined by the latitude where baroclinic eddies begin to occur. As surface temperatures are warmed, the latitude of baroclinic instability onset is shifted poleward due to increases in the static stability of the subtropics, which is increased in an atmosphere with higher moisture content. |
Fu Q., P. Lin, 2011: Poleward shift of subtropical jets inferred from satellite-observed lower-stratospheric temperatures. J.Climate, 24, 5597- 5603.10.1175/JCLI-D-11-00027.11d866b91fa7c2308e4af6ab8199ef14ahttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2011JCli...24.5597Fhttp://adsabs.harvard.edu/abs/2011JCli...24.5597FNot Available |
Held I. M., A. Y. Hou, 1980: Nonlinear axially symmetric circulations in a nearly inviscid atmosphere. J. Atmos. Sci., 37, 515- 533.10.1175/1520-0469(1980)037<0515:NASCIA>2.0.CO;2d3c4aa05de5e7d717e4697b213f6c3b8http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1980JAtS...37..515Hhttp://adsabs.harvard.edu/abs/1980JAtS...37..515HABSTRACT The structure of certain axially symmetric circulations in a stably stratified, differentially heated, rotating Boussinesq fluid on a sphere is analyzed. A simple approximate theory (similar to that introduced by Schneider (1977)) is developed for the case in which the fluid is sufficiently inviscid that the poleward flow in the Hadley cell is nearly angular momentum conserving. The theory predicts the width of the Hadley cell, the total poleward heat flux, the latitude of the upper level jet in the zonal wind, and the distribution of surface easterlies and westerlies. Fundamental differences between such nearly inviscid circulations and the more commonly studied viscous axisymmetric flows are emphasized. The theory is checked against numerical solutions to the model equations. |
Horel J. D., J. M. Wallace, 1981: Planetary-scale atmospheric phenomena associated with the Southern Oscillation. Mon. Wea. Rev., 109, 813- 829.3d359b89ddf30090ef1a97739fcdbdbehttp%3A%2F%2Fwww.bioone.org%2Fservlet%2Flinkout%3Fsuffix%3Di1551-5036-21-6-13-Horel1%26dbid%3D16%26doi%3D10.2112%252F05-0544.1%26key%3D10.1175%252F1520-0493%281981%291092.0.CO%253B2/s?wd=paperuri%3A%287cda283cda535906638c0e6e044fd567%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fwww.bioone.org%2Fservlet%2Flinkout%3Fsuffix%3Di1551-5036-21-6-13-Horel1%26dbid%3D16%26doi%3D10.2112%252F05-0544.1%26key%3D10.1175%252F1520-0493%281981%291092.0.CO%253B2&ie=utf-8&sc_us=6473185024131020186 |
Hou A. Y., 1998: Hadley circulation as a modulator of the extratropical climate. J. Atmos. Sci., 55, 2437- 2457.10.1175/1520-0469(1998)055<2437:HCAAMO>2.0.CO;23e70351ba3e348b453ed4593e04e1042http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1998JAtS...55.2437Hhttp://adsabs.harvard.edu/abs/1998JAtS...55.2437HStudies based on GCM ensemble forecasts have shown that an intensification of the cross-equatorial Hadley circulation associated with a latitudinal displacement of the zonally averaged convective heating in the Tropics can lead to remote warming in the winter high latitudes. This work further investigates this tropical-extratropical connection in a perpetual winter experiment using an idealized GCM without orography to focus on the role of transient eddies, and tests against observations using a multiyear reanalysis produced by the Goddard Earth Observing System-Version 1 (GEOS-1) Data Assimilation System.The GCM results show that the intensification and poleward expansion of the cross-equatorial Hadley cell induced by a tropical heating shift can lead to westerly acceleration in the winter subtropics and enhanced vertical shear of the zonal wind in the subtropics and midlatitudes. The increased baroclinicity outside the Tropics is accompanied by reduced meridional temperature and potential vorticity (PV) gradients, consistent with enhanced PV mixing and increased poleward heat transport by baroclinic eddies. But if the changes in the Hadley cell are such that they produce a deceleration of the zonal wind in the winter subtropics, stronger temperature and PV gradients result in the winter extratropics. The midlatitude response to Hadley acceleration of the subtropical jet is dominated by enhanced power in low-frequency planetary-scale waves that peaks at zonal wavenumber 2 with a period of 40 days.The extent to which this tropical-extratropical connection may be present in nature is tested using the GEOS-1 reanalysis for five austral winters from 1985 to 1989. Results show that the year-to-year variation in the zonally averaged extratropical temperature gradient in austral winters is correlated with the variation in the acceleration of the subtropical zonal wind by the winter Hadley cell. The anomaly correlation coefficients range from 0.80 to 0.92, depending on the statistical test. The positive Hadley acceleration anomaly in the subtropics during the 1988 austral winter is accompanied by stronger than normal zonal wind shears in the subtropics and midlatitudes, a colder troposphere in the midlatitudes, and a warmer pole. The extratropical temperature anomalies are associated with a reduced PV gradient, and the midlatitude geopotential height anomaly shows a spectral peak at wavenumbers 2-3 with periods between 40 and 60 days, similar to the idealized GCM results. The implication of this study is that the Hadley circulation may play a role in modulating the temperature difference between middle and high latitudes by modifying the zonal wind shear in the subtropics and midlatitudes. |
Hu Y., Q. Fu, 2007: Observed poleward expansion of the Hadley circulation since 1979. Atmos. Chem. Phys., 7, 5229- 5236.10.5194/acp-7-5229-2007f92774e6dc7cd5138089aeb8cfea6703http%3A%2F%2Fwww.oalib.com%2Fpaper%2F2705445http://www.oalib.com/paper/2705445Using three meteorological reanalyses and three outgoing long-wave radiation (OLR) datasets, we show that the Hadley circulation has a significant poleward expansion of about 2 to 4.5 degrees of latitude since 1979. The three reanalyses along with the MSU data all indicate that the poleward expansion of the Hadley circulation in each hemisphere occurs during its spring and fall seasons. Results from the OLR datasets do not have such seasonality. The expansion of the Hadley circulation implies a poleward expansion of the band of subtropical subsidence, leading to enhanced mid-latitude tropospheric warming and poleward shifts of the subtropical dry zone. This would contribute to an increased frequency of midlatitude droughts in both hemispheres. |
Hu Y. Y., C. Zhou, and J. P. Liu, 2011: Observational evidence for poleward expansion of the Hadley circulation. Adv. Atmos. Sci.,28, 33-44, doi: 10.1007/s00376-010-0032-1.10.1007/s00376-010-0032-1.8f17cc9b47e9a2a66bf1a2123e716185http%3A%2F%2Fwww.cnki.com.cn%2FArticle%2FCJFDTotal-DQJZ201101003.htmhttp://d.wanfangdata.com.cn/Periodical_dqkxjz-e201101003.aspxHow the Hadley circulation changes in response to global climate change and how its change impacts upon regional and global climates has generated a lot of interest in the literature in the past few years. In this paper, consistent and statistically significant poleward expansion of the Hadley circulation in the past few decades is demonstrated, using independent observational datasets as proxy measures of the Hadley circulation. Both observational outgoing longwave radiation and precipitation datasets show an annual average total poleward expansion of the Hadley cells of about 3.6 latitude. Sea level pressure from observational and reanalysis datasets show smaller magnitudes of poleward expansion, of about 1.2 latitude. Ensemble general circulation model simulations forced by observed time-varying sea surface temperatures were found to generate a total poleward expansion of about 1.23latitude. Possible mechanisms behind the changes in the horizontal extent of the Hadley circulation are discussed. |
Hu Y. Y., L. J. Tao, and J. P. Liu, 2013: Poleward expansion of the Hadley circulation in CMIP5 simulations. Adv. Atmos. Sci.,30, 790-795, doi: 10.1007/s00376-012-2187-4.10.1007/s00376-012-2187-4d56bd42a6e25a2779e82a77ebde477bdhttp%3A%2F%2Fwww.cqvip.com%2FQK%2F84334X%2F201303%2F45407369.htmlhttp://d.wanfangdata.com.cn/Periodical_dqkxjz-e201303019.aspx |
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. Cambridge University Press, Cambridge, UK and New York, NY, 1535 pp. |
Johanson C. M., Q. Fu, 2009: Hadley cell widening: Model simulations versus observations. J. Climate, 22, 2713- 2725.10.1175/2008JCLI2620.1c28d671f-304c-4af4-95e1-2ebffd587a0c178d913aa4731818d13be3d52cff7c10http%3A%2F%2Fwww.cabdirect.org%2Fabstracts%2F20093183449.htmlrefpaperuri:(c54fa233eaaab0c240291840bf5f01f0)http://www.cabdirect.org/abstracts/20093183449.htmlNot Available |
Kistler R., Coauthors, 2001: The NCEP-NCAR 50-year reanalysis: Monthly means CD-ROM and documentation. Bull. Amer. Meteor. Soc., 82, 247- 267.10.1175/1520-0477(2001)0822.3.CO;2bdaa6295-560e-4453-ba4f-e27295b593cf703e996c59a054bc1c4c768fa985b1c1http://ci.nii.ac.jp/naid/10013127425/http://ci.nii.ac.jp/naid/10013127425/Abstract No Abstract Available |
Kociuba G., S. B. Power, 2015: Inability of CMIP5 models to simulate recent strengthening of the Walker Circulation: Implications for projections. J.Climate, 28, 20- 35.10.1175/JCLI-D-13-00752.1bad90675b96931094de40bc56b229274http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2015JCli...28...20Khttp://adsabs.harvard.edu/abs/2015JCli...28...20KNot Available |
Kousky V. E., M. T. Kagano, and I. F. A. Cavalcanti, 1984: A review of the Southern Oscillation: Oceanic-atmospheric circulation changes and related rainfall anomalies. Tellus A, 36A, 490- 504.10.1111/j.1600-0870.1984.tb00264.xf815aae5e576cd01ffca4dc1d99faadchttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1111%2Fj.1600-0870.1984.tb00264.x%2Fcitedbyhttp://onlinelibrary.wiley.com/doi/10.1111/j.1600-0870.1984.tb00264.x/citedbyConsideration is given to aims, problems, and methods of structural optimization; continuum-based optimality criteria (COC) methods; optimal layout theory; layout optimization using the iterative COC algorithm; simple solutions for optimal layout of trusses; CAD-integrated structural topology and design optimization; structural optimization of linearly elastic structures using a homogenization method; and mixed elements in shape optimal design of structures based on global criteria. Attention is also given to shape optimal design of axisymmetric shell structures, applications of artificial neural nets in structural mechanics, mathematical programming techniques for shape optimization of skeleton structures; exact and approximate static structural reanalysis; shape optimization with FEM; sensitivity analysis with BEM; and the theorems of structural and geometric variation for engineering structures. (No individual items are abstracted in this volume) |
Kumar A., F. L. Yang, L. Goddard, and S. Schubert, 2004: Differing trends in the tropical surface temperatures and precipitation over land and oceans. J.Climate, 17, 653- 664.10.1175/1520-0442(2004)017<0653:DTITTS>2.0.CO;2cf1e813aab3dd2ac0d2df7afdc1fc007http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2004JCli...17..653Khttp://adsabs.harvard.edu/abs/2004JCli...17..653KCiteSeerX - Scientific documents that cite the following paper: 2004: Differing trends in the tropical surface temperatures and precipitation over land and oceans |
Krishnamurti T. N., 1971: Tropical east-west circulations during the northern summer. J. Atmos. Sci., 28, 1342- 1347.10.1175/1520-0469(1971)028<1342:TEWCDT>2.0.CO;218c210a76d4386a5c1347d5daec448cbhttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1971JAtS...28.1342Khttp://adsabs.harvard.edu/abs/1971JAtS...28.1342KObservational evidence of a major east-west circulation during the northern summer is presented in this paper. The geometry of this circulation is portrayed in the form of the streamlines of the divergent part of the wind for the seasonal mean motion field. It is, furthermore, shown that 1) the intensity of this circulation is comparable to that of the Hadley type circulation, 2) the circulation is thermally direct, 3) there is a generation of kinetic energy by these east-west over-turnings of mass, and 4) this circulation is distinctly different from the so called Walker circulation, the latter being a southern extension of the more vigorous east-west circulation. |
Lu J., G. A. Vecchi, and T. Reichler, 2007: Expansion of the Hadley cell under global warming. Geophys. Res. Lett., 34,L06805, doi: 10.1029/2006GL028443.10.1029/2006GL028443e6e580fb9d376c606ba3e1e50e73cd1fhttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2007GL030931%2Fpdf/s?wd=paperuri%3A%28fe565f4665bebf641642465795e7057e%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2007GL030931%2Fpdf&ie=utf-8&sc_us=15980245267232123770A consistent weakening and poleward expansion of the Hadley circulation is diagnosed in the climate change simulations of the IPCC AR4 project. Associated with this widening is a poleward expansion of the subtropical dry zone. Simple scaling analysis supports the notion that the poleward extent of the Hadley cell is set by the location where the thermally driven jet first becomes baroclinically unstable. The expansion of the Hadley cell is caused by an increase in the subtropical static stability, which pushes poleward the baroclinic instability zone and hence the outer boundary of the Hadley cell. |
Lucas C., H. Nguyen, and B. Timbal, 2012: An observational analysis of Southern Hemisphere tropical expansion. J. Geophys. Res., 117,D17112, doi: 10.1029/2011JD017033.10.1029/2011JD017033654c9f43559bf4cc1b50e2351ec50b86http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2011JD017033%2Fabstracthttp://onlinelibrary.wiley.com/doi/10.1029/2011JD017033/abstractHistorical radiosonde data are analyzed using the tropopause height frequency method to investigate the variation of the Southern Hemisphere tropical edge from 1979/80-2010/11, independently of reanalysis-derived data. Averaged across the hemisphere we identify a tropical expansion trend of 0.41 0.37 deg dec, significant at the 90% level. A comparison with four reanalyses shows generally consistent results between radiosondes and reanalyses. Estimated rates of tropical expansion in the SH are broadly similar, as is the interannual variability. However, notable differences remain. Some of these differences are related to the methodology used to identify the height of the tropopause in the reanalyses, which produces inconsistent results in the subtropics. Differences between radiosondes and reanalyses are also more manifest in data-poor regions. In these regions, the reanalyses are not fully constrained, allowing the internal model dynamics to drive the variability. The performance of the reanalyses varies temporally compared to the radiosonde data. These differences are particularly apparent from 1979 to 1985 and from 2001 to 2010. In the latter period, we hypothesize that the increased availability and quality of satellite-based data improves the results from the ERA Interim reanalysis, creating an inconsistency with earlier data. This apparent inhomogeneity results in a tropical expansion trend in that product that is inconsistent with the radiosonde-based observations. These results confirm the need for careful evaluation of reanalysis-based data for use in studies of long-term climate variability. |
Luo J. J., W. Sasaki, and Y. Masumoto, 2012: Indian Ocean warming modulates Pacific climate change. Proceedings of the National Academy of Sciences of the United States of America, 109, 18701- 18706.10.1073/pnas.1210239109231121747cb2520c312fcc31fc8b8e8ae35ae952http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpubmed%2F23112174http://med.wanfangdata.com.cn/Paper/Detail/PeriodicalPaper_PM23112174It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Niña-like state (with enhanced east-west Walker circulation) through the Pacific ocean-atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific's could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries. |
Ma S. M., T. J. Zhou, 2014: Changes of the tropical Pacific Walker circulation simulated by two versions of FGOALS model. Science China Earth Sciences, 57, 2165- 2180.10.1007/s11430-014-4902-8885f99e90449b8632b75fc34cfcc1764http%3A%2F%2Flink.springer.com%2F10.1007%2Fs11430-014-4902-8http://www.cnki.com.cn/Article/CJFDTotal-JDXG201409017.htmHere we assessed the performances of IAP/LASG climate system model FGOALS-g2 and FGOAS-s2 in the simulation of the tropical Pacific Walker circulation(WC). Both models reasonably reproduce the climatological spatial distribution features of the tropical Pacific WC. We also investigated the changes of WC simulated by two versions of FGOALS model and discussed the mechanism responsible for WC changes. Observed Indo-Pacific sea level pressure(SLP) reveals a reduction of WC during 1900–2004 and 1950–2004, and an enhancement of WC during 1982–2004. During the three different time spans, the WC in FGOALS-g2 shows a weakening trend. In FGOALS-s2, tropical Pacific atmospheric circulation shows no significant change over the past century, but the WC strengthens during 1950–2004 and 1982–2004. The simulated bias of the WC change may be related to the phase of the multi-decadal mode in coupled models, which is not in sync with that in the observations. The change of WC is explained by the hydrological cycle constraints that precipitation must be balanced with the moisture transporting from the atmospheric boundary layer to the free troposphere. In FGOALS-g2, the increasing amplitude of the relative variability of precipitation(?P/P) is smaller(larger) than the relative variability of moisture(?q/q) over the tropical western(eastern) Pacific over the three time spans, and thus leads to a weakened WC. In FGOALS-s2, the convective mass exchange fluxes increase(decrease) over the tropical western(eastern) Pacific over the past 53 a(1950–2004) and the last 23 a(1982– 2004), and thus leads to a strengthened WC. The distributions of sea surface temperature(SST) trends dominate the change of WC. Over the past 55 a and 23 a, tropical Pacific SST shows an El Ni?o-like(a La Ni?a-like) trend pattern in FGOALS-g2(FGOALS-s2), which drives the weakening(strengthening) of WC. Therefore, a successful simulation of the tropical Pacific SST change pattern is necessary for a reasonable simulation of WC change in climate system models. This idea is further supported by the diagnosis of historical sea surface temperature driven AGCM-simulations. |
Min S.-K., S.-W. Son, 2013: Multimodel attribution of the Southern Hemisphere Hadley cell widening: Major role of ozone depletion. J. Geophys. Res.: Atmos.,118, 3007-3015, doi: 10.1002/jgrd.50232.10.1002/jgrd.502325e61aefd3f9b8a59c2288296864291bahttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2Fjgrd.50232%2Fabstracthttp://onlinelibrary.wiley.com/doi/10.1002/jgrd.50232/abstracthas been suggested that the Hadley cell has been widening during the past three decades in both hemispheres, but attribution of its cause(s) remains challenging. By applying an optimal fingerprinting technique to 7 modern reanalyses and 49 coupled climate models participating in the CMIP3 and CMIP5, here we detect an influence of human-induced stratospheric ozone depletion on the observed expansion of the Hadley cell in the Southern Hemisphere (SH) summer. The detected signal is found to be separable from other external forcings that include greenhouse gases (GHGs), confirming a dominant role of stratospheric ozone in the SH summer climate change. Our results are largely insensitive to observational and model uncertainties, providing additional evidence for a human contribution to the atmospheric circulation changes. |
Nguyen H., A. Evans, C. Lucas, I. Smith, and B. Timbal, 2013: The Hadley circulation in reanalyses: Climatology, variability, and change. J.Climate, 26, 3357- 3376.10.1175/JCLI-D-12-00224.18c9450401bd2ef509d9e4e48795e8589http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2013JCli...26.3357Nhttp://adsabs.harvard.edu/abs/2013JCli...26.3357NAbstract Analysis of the annual cycle of intensity, extent, and width of the Hadley circulation across a 31-yr period (1979–2009) from all existent reanalyses reveals a good agreement among the datasets. All datasets show that intensity is at a maximum in the winter hemisphere and at a minimum in the summer hemisphere. Maximum and minimum values of meridional extent are reached in the respective autumn and spring hemispheres. While considering the horizontal momentum balance, where a weakening of the Hadley cell (HC) is expected in association with a widening, it is shown here that there is no direct relationship between intensity and extent on a monthly time scale. All reanalyses show an expansion in both hemispheres, most pronounced and statistically significant during summer and autumn at an average rate of expansion of 0.55° decade 611 in each hemisphere. In contrast, intensity trends are inconsistent among the datasets, although there is a tendency toward intensification, particularly in winter and spring. Correlations between the HC and tropical and extratropical large-scale modes of variability suggest interactions where the extent of the HC is influenced by El Ni09o–Southern Oscillation (ENSO) and the annular modes. The cells tend to shrink (expand) during the warm (cold) phase of ENSO and during the low (high) phase of the annular modes. Intensity appears to be influenced only by ENSO and only during spring for the southern cell and during winter for the northern cell. |
Nicholls N., 2008: Recent trends in the seasonal and temporal behaviour of the El Niño-Southern Oscillation. Geophys. Res. Lett., 35,L19703, doi: 10.1029/2008GL034499.10.1029/2008GL0344991d2b4cf09d1b8568ccc5fcbc9ff2672ehttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2008GL034499%2Fcitedbyhttp://onlinelibrary.wiley.com/doi/10.1029/2008GL034499/citedbyTrends in the seasonal and temporal behaviour of the El Ni09o-Southern Oscillation over the period 1958-2007 have been assessed using two indices of the phenomenon, NINO3.4 and a non-standardised Southern Oscillation Index (SOI). There is no evidence of trends in the variability or the persistence of the indices, nor in their seasonal patterns. There is a trend towards what might be considered more ``El Ni09o-like'' behaviour in the SOI (and more weakly in NINO3.4), but only through the period March-September and not in November-February, the season when El Ni09o and La Ni09a events typically peak. The trend in the SOI reflects only a trend in Darwin pressures, with no trend in Tahiti pressures. Apart from this trend, the temporal/seasonal nature of the El Ni09o-Southern Oscillation has been remarkably consistent through a period of strong global warming. |
Oort A. H., J. J. Yienger, 1996: Observed interannual variability in the Hadley circulation and its connection to ENSO. J.Climate, 9, 2751- 2767.10.1175/1520-0442(1996)009<2751:OIVITH>2.0.CO;2f82f813602150315bb3ead98c6804c0ahttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1996JCli....9.2751Ohttp://adsabs.harvard.edu/abs/1996JCli....9.2751OAbstract Based on a 26-yr set of daily global upper-air wind data for the period January 1964–December 1989, the interannual variability in the strength of the tropical Hadley cells is investigated. Although several measures of the intensity of the zonal-mean cells are discussed, the main focus is on the maximum in the streamfunction in the northern and southern Tropics. The streamfunction was computed from observed monthly mean latitude versus pressure cross sections of the zonal-mean meridional wind component. Significant seasonal variations are found in the strength, latitude, and height of the maximum streamfunction for both Hadley cells. Significant correlations are also observed between the Hadley cells and the El Ni09o-Southern Oscillation phenomenon. During the extreme seasons, only one “winter” Hadley cell dominates the Tropics, with the rising branch in the summer hemisphere and the sinking branch in the winter hemisphere. Superimposed on this “normal” one-cell winter Hadley circulation in the Tropics are two strengthened direct (i.e., energy releasing) Hadley cells found during episodes of warm sea surface temperature anomalies in the eastern equatorial Pacific (El Ni09o) and weakened Hadley cells during episodes of cold anomalies. The anomalies in the strength of the Hadley cells are strongly and inversely correlated with the anomalies in the strength of the Walker oscillation. |
Polvani L. M., D. W. Waugh, G. J. P. Correa, and S. W. Son, 2011: Stratospheric ozone depletion: The main driver of twentieth-century atmospheric circulation changes in the southern hemisphere. J.Climate, 24, 795- 812.2b359bfdf8cd1b2d3aab9be74b31e13chttp%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2011JCli...24..795P%26db_key%3DPHY%26link_type%3DABSTRACT/s?wd=paperuri%3A%280f1e29fe75d16daf7a8ae1ad5d5dd134%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fcgi-bin%2Fnph-data_query%3Fbibcode%3D2011JCli...24..795P%26db_key%3DPHY%26link_type%3DABSTRACT&ie=utf-8&sc_us=12870173539570706968 |
Power S. B., G. Kociuba, 2011: The impact of global warming on the Southern Oscillation Index. Climate Dyn., 37, 1745- 1754.10.1007/s00382-010-0951-7c05a60fcfcb681be5771793bde843c9fhttp%3A%2F%2Flink.springer.com%2F10.1007%2Fs00382-010-0951-7http://link.springer.com/10.1007/s00382-010-0951-7The Southern Oscillation Index (SOI)-a measure of air pressure difference across the Pacific Ocean, from Tahiti in the south-east to Darwin in the west-is one of the world's most important climatic indices. The SOI is used to track and predict changes in both the El Niño-Southern Oscillation phenomenon, and the Walker Circulation (WC). During El Niño, for example, the WC weakens and the SOI tends to be negative. Climatic variations linked to changes in the WC have a profound influence on climate, ecosystems, agriculture, and societies in many parts of the world. Previous research has shown that (1) the WC and the SOI weakened in recent decades and that (2) the WC in climate models tends to weaken in response to elevated atmospheric greenhouse gas concentrations. Here we examine changes in the SOI and air pressure across the Pacific in the observations and in numerous WCRP/CMIP3 climate model integrations for both the 20th and 21st centuries. The difference in mean-sea level air pressure (MSLP) between the eastern and western equatorial Pacific tends to weaken during the 21st century, consistent with previous research. Here we show that this primarily arises because of an increase in MSLP in the west Pacific and not a decline in the east. We also show, in stark contrast to expectations, that the SOI actually tends to increase during the 21st century, not decrease. Under global warming MSLP tends to increase at both Darwin and Tahiti, but tends to rise more at Tahiti than at Darwin. Tahiti lies in an extensive region where MSLP tends to rise in response to global warming. So while the SOI is an excellent indicator of interannual variability in both the equatorial MSLP gradient and the WC, it is a highly misleading indicator of long-term equatorial changes linked to global warming. Our results also indicate that the observed decline in the SOI in recent decades has been driven by natural, internally generated variability. The externally forced signal in the June-December SOI during 2010 is estimated to be approximately 5% of the standard deviation of variability in the SOI during the 20th century. This figure is projected to increase to 40% by the end of the 21st century under the A2 SRES scenario. The 2010 global warming signal is already a major contributor to interdecadal variability in the SOI, equal to 45% of the standard deviation of 30-year running averages of the SOI. This figure is projected to increase to nearly 340% by the end of the 21st century. Implications that these discoveries have for understanding recent climatic change and for seasonal prediction are discussed. |
Quan X. W., H. F. Diaz, and M. P. Hoerling, 2004: Change in the tropical Hadley cell since 1950. The Hadley Circulation: Past, Present, and Future, H. F. Diaz and R. S. Bradley,Eds., Springer, 85- 120.97d5f80eae30d848983f8144458c083fhttp%3A%2F%2Fwww.bokus.com%2Fbok%2F9781402029431%2Fthe-hadley-circulation%2Fhttp://www.bokus.com/bok/9781402029431/the-hadley-circulation/Present, Past and Future |
Ropelewiski C. F., M. S. Halpert, 1989: Precipitation patterns associated with the high index phase of the Southern Oscillation. J.Climate, 2, 268- 284.a4b60a85f5155fea8c24310378d002b6http%3A%2F%2Fwww.bioone.org%2Fservlet%2Flinkout%3Fsuffix%3Di0276-4741-32-4-431-Ropelewski2%26dbid%3D16%26doi%3D10.1659%252FMRD-JOURNAL-D-12-00062.1%26key%3D10.1175%252F1520-0442%281989%290022.0.CO%253B2/s?wd=paperuri%3A%284115150d74628d9a4db147f94c95c77a%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fwww.bioone.org%2Fservlet%2Flinkout%3Fsuffix%3Di0276-4741-32-4-431-Ropelewski2%26dbid%3D16%26doi%3D10.1659%252FMRD-JOURNAL-D-12-00062.1%26key%3D10.1175%252F1520-0442%281989%290022.0.CO%253B2&ie=utf-8&sc_us=1488089432380483318 |
Seo K. H., D. M. W. Frierson, and J. H. Son, 2014: A mechanism for future changes in Hadley circulation strength in CMIP5 climate change simulations. Geophys. Res. Lett.,41, 5251-5258, doi: 10.1002/2014GL060868.10.1002/2014GL0608684f651e4c92500d662d446cb5c72159f0http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2F2014GL060868%2Fabstracthttp://onlinelibrary.wiley.com/doi/10.1002/2014GL060868/abstractThe Coupled Model Intercomparison Project Phase 5 (CMIP5) 21st century climate change simulations exhibit a robust (slight) weakening of the Hadley cell (HC) during the boreal winter (summer, respectively) season in the future climate. Using 30 different coupled model simulations, we investigate the main mechanisms for both the multimodel ensemble mean changes in the HC strength and its intermodel changes in response to global warming during these seasons. A simple scaling analysis relates the strength of the HC to three factors: the meridional potential temperature gradient, gross static stability, and tropopause height. We found that changes in the meridional potential temperature gradients across the subtropics in a warming climate play a crucial role in the ensemble mean changes and model-to-model variations in the HC strength for both seasons. A larger reduction in the meridional temperature gradient in the Northern Hemisphere in boreal winter leads to the larger reduction of the HC strength in that season. |
Tanaka H. L., N. Ishizaki, and A. Kitoh, 2004: Trend and interannual variability of Walker, monsoon and Hadley circulations defined by velocity potential in the upper troposphere. Tellus A, 56, 250- 269.10.1111/j.1600-0870.2004.00049.x0ecca1340af4f61f12112ddfed980253http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1111%2Fj.1600-0870.2004.00049.x%2Fpdfhttp://onlinelibrary.wiley.com/doi/10.1111/j.1600-0870.2004.00049.x/pdfABSTRACT In this paper, we attempt to divide the global divergent field at the upper troposphere in contributions from the Hadley, Walker and monsoon circulations, using a monthly mean velocity potential field at 200-hPa level. First, the zonal mean of the velocity potential is analysed to represent the Hadley circulation. The deviation from the zonal mean is then divided into its annual mean and the seasonal cycle parts, which are considered to represent the Walker and monsoon circulations, respectively. The intensities of each circulation are measured by their peaks in the velocity potential field separated in each component. According to this separation, the mean intensities of the Walker, monsoon and Hadley circulations appear to be 120: 60: 40 (× 10 5 m 2 s 611 ) in January and 120: 90: 45 (×10 5 m 2 s 611 ) in July, respectively. Based on this simple definition, interannual variabilities of each circulation are then examined quantitatively using the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. The time series of the intensity of the Walker circulation coincides with the Southern Oscillation index (SOI), and the intensity has weakened in recent decades. That of the Hadley circulation indicates intensifying trend in boreal winter. Finally, the same analysis is applied for the model atmosphere by the Meteorological Research Institute (MRI) coupled atmosphere–ocean general circulation model (CGCM1) with a gradual increase in CO 2 at a compound rate of 1% yr 611 for 150 yr. It is shown that the Hadley circulation intensifies by 40% and the monsoon circulation decays by 20% in boreal summer when the global warming has occurred in a century later. The result demonstrates that the proposed simple separation of the tropical circulation in the Walker, monsoon and Hadley components is useful, although it is not rigorous, for the initial assessment of the model response to the global warming. |
Taylor K. E., B. J. Stouffer, and G. A. Meehl, 2012: An overview of CMIP5 and the experiment design. Bull. Amer. Meteor. Soc., 93, 485- 498.10.1175/BAMS-D-11-00094.10a93ff62-7ac1-4eaa-951b-da834bb5d6acd378bae55de68ca8b37ba4ba57a3c0b9http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2012BAMS...93..485Trefpaperuri:(102c64f576f0dc49ca552e6df691421b)http://adsabs.harvard.edu/abs/2012BAMS...93..485TThe fifth phase of the Coupled Model Intercomparison Project (CMIP5) will produce a state-of-the- art multimodel dataset designed to advance our knowledge of climate variability and climate change. Researchers worldwide are analyzing the model output and will produce results likely to underlie the forthcoming Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Unprecedented in scale and attracting interest from all major climate modeling groups, CMIP5 includes “long term” simulations of twentieth-century climate and projections for the twenty-first century and beyond. Conventional atmosphere–ocean global climate models and Earth system models of intermediate complexity are for the first time being joined by more recently developed Earth system models under an experiment design that allows both types of models to be compared to observations on an equal footing. Besides the longterm experiments, CMIP5 calls for an entirely new suite of “near term” simulations focusing on recent decades and the future to year 2035. These “decadal predictions” are initialized based on observations and will be used to explore the predictability of climate and to assess the forecast system's predictive skill. The CMIP5 experiment design also allows for participation of stand-alone atmospheric models and includes a variety of idealized experiments that will improve understanding of the range of model responses found in the more complex and realistic simulations. An exceptionally comprehensive set of model output is being collected and made freely available to researchers through an integrated but distributed data archive. For researchers unfamiliar with climate models, the limitations of the models and experiment design are described. |
Tokinaga H., S.-P. Xie, C. Deser, Y. Kosaka, and Y. M. Okumura, 2012: Slowdown of the Walker circulation driven by tropical Indo-Pacific warming. Nature, 491, 439- 443.10.1038/nature11576231515884690cd56af048bd7cf2661e540e5ab29http%3A%2F%2Fwww.nature.com%2Fnature%2Fjournal%2Fv491%2Fn7424%2Fabs%2Fnature11576.htmlhttp://med.wanfangdata.com.cn/Paper/Detail/PeriodicalPaper_PM23151588Global mean sea surface temperature () has risen steadily over the past century, but the overall pattern contains extensive and often uncertain spatial variations, with potentially important effects on regional precipitation. Observations suggest a slowdown of the zonal atmospheric overturning circulation above the tropical Pacific Ocean (the Walker circulation) over the twentieth century. Although this change has been attributed to a muted hydrological cycle forced by global warming, the effect of warming patterns has not been explored and quantified. Here we perform experiments using an atmospheric model, and find that warming patterns are the main cause of the weakened Walker circulation over the past six decades (1950-2009). The trend reconstructed from bucket-sampled and night-time marine surface air temperature features a reduced zonal gradient in the tropical -Pacific Ocean, a change consistent with subsurface temperature observations. Model experiments with this trend pattern robustly simulate the observed changes, including the Walker circulation slowdown and the eastward shift of atmospheric convection from the Indonesian maritime continent to the central tropical Pacific. Our results cannot establish whether the observed changes are due to natural variability or anthropogenic global warming, but they do show that the observed slowdown in the Walker circulation is presumably driven by oceanic rather than atmospheric processes. |
Vecchi G. A., B. J. Soden, A. T. Wittenberg, I. M. Held, A. Leetmaa, and M. J. Harrison, 2006: Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing. Nature, 441, 73- 76.10.1038/nature0474416672967e7807ab6c99d5443f6f226967fbda868http%3A%2F%2Fonlinelibrary.wiley.com%2Fresolve%2Freference%2FADS%3Fid%3D2006Natur.441...73Vhttp://med.wanfangdata.com.cn/Paper/Detail/PeriodicalPaper_PM16672967Abstract Since the mid-nineteenth century the Earth's surface has warmed, and models indicate that human activities have caused part of the warming by altering the radiative balance of the atmosphere. Simple theories suggest that global warming will reduce the strength of the mean tropical atmospheric circulation. An important aspect of this tropical circulation is a large-scale zonal (east-west) overturning of air across the equatorial Pacific Ocean--driven by convection to the west and subsidence to the east--known as the Walker circulation. Here we explore changes in tropical Pacific circulation since the mid-nineteenth century using observations and a suite of global climate model experiments. Observed Indo-Pacific sea level pressure reveals a weakening of the Walker circulation. The size of this trend is consistent with theoretical predictions, is accurately reproduced by climate model simulations and, within the climate models, is largely due to anthropogenic forcing. The climate model indicates that the weakened surface winds have altered the thermal structure and circulation of the tropical Pacific Ocean. These results support model projections of further weakening of tropical atmospheric circulation during the twenty-first century. |
Wang C. Z., 2002a: Atmospheric circulation cells associated with the El Niño-Southern Oscillation. J.Climate, 15, 399- 419.9ac69b31-d2f4-453c-927d-c6589f6871a998057db0212b63dc4fac992ed8d903fdhttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2002JCli...15..399Wrefpaperuri:(2c82991f3db2a12690f7b52de8957268)/s?wd=paperuri%3A%282c82991f3db2a12690f7b52de8957268%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2002JCli...15..399W&ie=utf-8 |
Wang C. Z., 2002b: Atlantic climate variability and its associated atmospheric circulation cells. J.Climate, 15, 1516- 1536.10.1175/1520-0442(2002)015<1516:ACVAIA>2.0.CO;2b52000f2-f67e-4f03-ac16-66befb739b88648723577beff3362cb68caca1cbce71http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2002JCli...15.1516Wrefpaperuri:(0cb1e4a5a00f99f267f5213e96324115)http://adsabs.harvard.edu/abs/2002JCli...15.1516WPhenomena important for Atlantic climate variability include the Atlantic zonal equatorial mode, the tropical Atlantic meridional gradient mode, and the North Atlantic Oscillation (NAO). These climate phenomena and their associated atmospheric circulation cells are described and discussed using the NCEP-NCAR reanalysis field and the NCEP sea surface temperature (SST) from January 1950 to December 1999. Atmospheric divergent wind and vertical motion are used for the identification of atmospheric circulation cells. During the peak phase of the Atlantic equatorial mode, the Atlantic Walker circulation weakens and extends eastward, which results in surface westerly wind anomalies in the equatorial western Atlantic. These westerly wind anomalies are partly responsible for warming in the equatorial eastern Atlantic that occurs in the second half of the year. The Atlantic equatorial mode involves a positive ocean-atmosphere feedback associated with the Atlantic Walker circulation, similar to the Pacific El Niño. The tropical Atlantic meridional gradient mode is characterized by a strong SST gradient between the tropical North Atlantic (TNA) and the tropical South Atlantic. Corresponding to the meridional gradient mode is an atmospheric meridional circulation cell in which the air rises over the warm SST anomaly region, flows toward the cold SST anomaly region aloft, sinks in the cold SST anomaly region, then crosses the equator toward the warm SST region in the lower troposphere. The analysis presented here suggests that the Pacific El Niño can affect the TNA through the Walker and Hadley circulations, favoring the TNA warming in the subsequent spring of the Pacific El Niño year. The NAO, characterized by strong westerly airflow between the Icelandic low and the Azores high, is also related to an atmospheric meridional circulation. During the high NAO index, the atmospheric Ferrel and Hadley cells are strengthened, consistent with surface westerly and easterly wind anomalies in the North Atlantic and in the mid-to-tropical Atlantic, respectively. |
Yu B., F. W. Zwiers, 2010: Changes in equatorial atmospheric zonal circulations in recent decades. Geophys. Res. Lett., 37,L05701, doi: 10.1029/2009GL042071.10.1029/2009GL042071ad505e6d38972910ba05dd6c111807c3http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2009GL042071%2Fpdfhttp://onlinelibrary.wiley.com/doi/10.1029/2009GL042071/pdfThe equatorial zonal circulation is characterized by the atmospheric mass flux, and is calculated using the NCEP-NCAR and ERA-40 reanalysis products. A speed-up of the equatorial circulations over the Atlantic and Indian oceans is found in recent decades in both reanalyses, in conjunction with a slow-down of the Pacific Walker circulation. These changes in the equatorial circulations are consistent with changes in dynamically related heating in the tropics, and with observed changes in precipitation. |
Zhou B. T., J. H. Wang, 2006a: Relationship between the boreal spring Hadley circulation and the summer precipitation in the Yangtze River valley. J. Geophys. Res., 111,D16109, doi: 10.1029/2005JD007006.10.1029/2005JD007006d044aeabdccd046c644f00e44323b5b8http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2005JD007006%2Fpdfhttp://en.cnki.com.cn/Article_en/CJFDTOTAL-QHYH200802006.htmIt is indicated by analysis of observed data that spring Hadley circulation anomaly can result in the variability of the East Asian summer atmospheric circulations and further impact the summer precipitation in the Yangtze River valley.A simulation by IAP9L-AGCM is performed on the responses of the East Asian atmospheric circulations and precipitation in the Yangtze River valley to strong spring Hadley circulation.Results show that related to strong spring Hadley circulation,East Asian summer monsoon is weakened and western Pacific subtropical high and South Asian high in summer are strengthened.Convection of east of the Philippines is reduced as well.All of these provide favorable conditions for increasing the precipitation in the Yangtze River valley.the simulation results agree with those from the diagnoses. |
Zhou B. T., H. J. Wang, 2006b: Interannual and interdecadal variations of the Hadley circulation and its connection with tropical sea surface temperature. Chinese Journal of Geophysics, 49( 5), 1147- 1154.10.1002/cjg2.939ba41aa20afbc0d5ad3e5d6094b267113http%3A%2F%2Fen.cnki.com.cn%2Farticle_en%2Fcjfdtotal-dqwx200605004.htmhttp://en.cnki.com.cn/article_en/cjfdtotal-dqwx200605004.htmThe variations of the Northern Hemispheric Hadley circulation in winter and the Southern Hemispheric Hadley circulation in summer and their connections with tropical sea surface temperature(SST) on interannual and interdecadal scale are studied by use of NCEP/NCAR wind data and NOAA SST data.It is indicated that the winter Northern Hemispheric Hadley circulation not only exhibits remarkably interannual and interdecadal variability,but also shows a positive trend.Accompanying the strengthened winter Northern Hemispheric Hadley circulation,its center shifts southward and its height ascends.The summer Southern Hemispheric Hadley circulation,lacking an obvious trend,exhibits decadal variations with strong,weak and strong pattern.The results also show that a positive correlation between the Northern Hemispheric Hadley circulation and the Nino3 region SST in winter exists,and this correlation changes on the interdecadal scale.It is also revealed that Nino3 region SST is positively correlated with the Northern Hemispheric Hadley circulation in winter and negatively correlated with the Southern Hemispheric Hadley circulation in summer on the interannual scale,which means when SST in the mid-east Pacific becomes warmer(colder), both winter and summer Hadley circulations get stronger(weaker). |
Zhou B. T., H. J. Wang, 2008: Relationship between Hadley circulation and sea ice extent in the Bering sea. Chinese Science Bulletin, 53( 3), 444- 449.10.1007/s11434-007-0451-2a273ddbe78fc8930427c4f753b8bfcfdhttp%3A%2F%2Fonlinelibrary.wiley.com%2Fresolve%2Freference%2FXREF%3Fid%3D10.1007%2Fs11434-007-0451-2http://www.cnki.com.cn/Article/CJFDTotal-JXTW200803023.htmThe linkage between Hadley circulation (HC) and sea ice extent in the Bering Sea during March- pril is investigated through an analysis of observed data in this research. It is found that HC is negatively correlated to the sea ice extent in the Bering Sea, namely, strong (weak) HC is corresponding to less (more) sea ice in the Bering Sea. The present study also addresses the large-scale atmospheric general circulation changes underlying the relationship between HC and sea ice in the Bering Sea. It follows that a positive phase of HC corresponds to westward located Aleutian low, anomalous southerlies over the eastern North Pacific and higher temperature in the Bering Sea, providing unfavorable atmospheric and thermal conditions for the sea ice forming, and thus sea ice extent in the Bering Sea is decreased, and vice versa . In addition, it is further identified that East Asian-North Pacific-North America teleconnection may play an important role in linking HC and changes of atmospheric circulations as well as sea ice in the Bering Sea. |
Zhou B. T., X. Cui, 2008: Hadley circulation signal in the tropical cyclone frequency over the western North Pacific. J. Geophys. Res., 113,D16107, doi: 10.1029/2007JD009156.10.1029/2007JD0091569dd1da81699a514cc970efe51d13a1e7http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2007JD009156%2Ffullhttp://onlinelibrary.wiley.com/doi/10.1029/2007JD009156/fullThe relationship between the boreal spring (March-May) Hadley circulation (HC) and the following summer (June-September) tropical cyclone (TC) frequency expressed as the total number of TCs in the western North Pacific is investigated through using the observed data. Results show that the spring HC is negatively correlated to the summer TC frequency. Such a relationship can be explained by the changes of the atmospheric circulations related to anomalous spring HC. A strong spring HC is followed by the weaker East Asian monsoon, stronger vertical zonal wind shear, and reduced convection over the western North Pacific in summer, which are unfavorable for TC genesis, and vice versa. The potential mechanism of how the spring HC affects the summer atmospheric circulations is also preliminarily identified. It is found that sea surface temperature (SST) anomalies in the Indian Ocean and the South China Sea may play important roles, since an anomalous spring HC can excite simultaneous SST anomalies, which can persist to the following summer and in turn give rise to the atmospheric anomalies associated with TC activities. Thus the variation of the spring HC can be a potential indicator in predicting summer TC activities over the western North Pacific. |