Ashok K., S. K. Behera, S. A. Rao, H. Y. Weng, and T. Yamagata, 2007: El Niño Modoki and its possible teleconnection. J. Geophys. Res.: Oceans, 112, C11007.10.1029/2006JC00379840d0c13a-a855-452f-b9dc-0947592e2d099ed3e543c8e9bfe16c01f5a1395c1babhttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2006JC003798%2Fabstract%3Bjsessionid%3DF2C5797F7539FC367A07E919851C7401.f03t02refpaperuri:(42a43d3a8b5a3852d00d87760b9d78f8)http://onlinelibrary.wiley.com/doi/10.1029/2006JC003798/abstract;jsessionid=F2C5797F7539FC367A07E919851C7401.f03t02[1] Using observed data sets mainly for the period 1979–2005, we find that anomalous warming events different from conventional El Ni09o events occur in the central equatorial Pacific. This unique warming in the central equatorial Pacific associated with a horseshoe pattern is flanked by a colder sea surface temperature anomaly (SSTA) on both sides along the equator. empirical orthogonal function (EOF) analysis of monthly tropical Pacific SSTA shows that these events are represented by the second mode that explains 12% of the variance. Since a majority of such events are not part of El Ni09o evolution, the phenomenon is named as El Ni09o Modoki (pseudo-El Ni09o) (“Modoki” is a classical Japanese word, which means “a similar but different thing”). The El Ni09o Modoki involves ocean-atmosphere coupled processes which include a unique tripolar sea level pressure pattern during the evolution, analogous to the Southern Oscillation in the case of El Ni09o. Hence the total entity is named as El Ni09o–Southern Oscillation (ENSO) Modoki. The ENSO Modoki events significantly influence the temperature and precipitation over many parts of the globe. Depending on the season, the impacts over regions such as the Far East including Japan, New Zealand, western coast of United States, etc., are opposite to those of the conventional ENSO. The difference maps between the two periods of 1979–2004 and 1958–1978 for various oceanic/atmospheric variables suggest that the recen
Chen Z. S., Z. P. Wen, R. G. Wu, P. Zhao, and J. Cao, 2014: Influence of two types of El Niños on the East Asian climate during boreal summer: A numerical study. Climate Dyn., 43, 469- 481.30749ba6-bdc8-43d0-abee-5bfd74af7b62141e861fb14f63cf41aa32026f15eac6http%3A%2F%2Flink.springer.com%2F10.1007%2Fs00382-013-1943-1refpaperuri:(e7d4d9010e912477decc8666ee57ed5c)/s?wd=paperuri%3A%28e7d4d9010e912477decc8666ee57ed5c%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Flink.springer.com%2F10.1007%2Fs00382-013-1943-1&ie=utf-8&sc_us=6744734652566482819
Feng J., J. P. Li, 2011: Influence of El Niño Modoki on spring rainfall over south China. J. Geophys. Res.: Atmos., 116, D13102.10.1029/2010JD015160e667fa0f-2a4e-4f46-a974-0ddc6f51376143e3316bb6f806cb7c77b73dc4cf788fhttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2010JD015160%2Fpdf%2Fenhancedrefpaperuri:(4d9d878ed43b03a2c6471e57da42e5c3)http://onlinelibrary.wiley.com/doi/10.1029/2010JD015160/pdf/enhancedUsing observed data sets from 1979 to 2006, the relationship between El Ni09o Modoki and spring rainfall over south China (SC) is investigated. Of particular interest is the difference in the influence on spring rainfall of typical El Ni09o events and the recently recognized El Ni09o Modoki events, which are characterized by distinct warm sea surface temperature anomalies (SSTA) in the central Pacific and weaker cold anomalies in the western and eastern parts of the basin. Associated with the SSTA, anomalous ascent occurs over the central Pacific and downward flow is observed over the eastern and western Pacific. The anomalous flow is associated with anomalous convergence in the upper troposphere over the western Pacific. SC is influenced by an anomalous anticyclonic circulation with prevailing northeasterly anomalies. The convective activity in SC becomes weaker, resulting in reduced rainfall. However, the situation is different in the case of El Ni09o, in terms of the influence on rainfall over SC. While El Ni09o Modoki events are accompanied by a significant reduction in rainfall over SC, there is enhanced rainfall associated with El Ni09o events. Moreover, there exists a strong asymmetry in the relationship between SC spring rainfall, typical El Ni09o-Southern Oscillation (ENSO) and ENSO Modoki events. It appears that these relationships are only statistically significant for positive events. The asymmetric influence of positive and negative in two ENSO phenomena may explain the difference in their respective relationships with spring rainfall over SC.
Gushchina D., B. Dewitte, 2012: Intraseasonal tropical atmospheric variability associated with the two flavors of El Niño. Mon. Wea. Rev., 140, 3669- 3681.
Hendon H. H., C. D. Zhang, and J. D. Glick, 1999: Interannual variation of the Madden-Julian oscillation during austral summer. J.Climate, 12, 2538- 2550.be742f50327233469489774bf66f7378http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1999jcli...12.2538h/s?wd=paperuri%3A%28ec235333f148c8c634fa5ff017bd4df5%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1999jcli...12.2538h&ie=utf-8&sc_us=6593899536110148732
Hendon H. H., M. C. Wheeler, and C. D. Zhang, 2007: Seasonal dependence of the MJO-ENSO relationship. J.Climate, 20, 531- 543.af246c0d-8be1-42dc-8315-6f8d97f3055e1343dad17627bbe2890aae7e4ec67f1dhttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2007JCli...20..531Hrefpaperuri:(d3ada79167f30598a47b92ddc6963f6e)/s?wd=paperuri%3A%28d3ada79167f30598a47b92ddc6963f6e%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2007JCli...20..531H&ie=utf-8&sc_us=17461309860912955640
Kao H. Y., J. Y. Yu, 2009: Contrasting eastern-Pacific and central-Pacific types of ENSO. J.Climate, 22, 615- 632.10.1175/2008JCLI2309.145c44667cdecca214fcb46319cfa9a89http%3A%2F%2Fwww.cabdirect.org%2Fabstracts%2F20093117308.htmlhttp://www.cabdirect.org/abstracts/20093117308.htmlNot Available
Kessler W. S., 2001: EOF representations of the Madden-Julian Oscillation and its connection with ENSO. J.Climate, 14, 3055- 3061.10.1175/1520-0442(2001)014<3055:EROTMJ>2.0.CO;2b35f071a-5f22-4a7c-b646-95fa72b12044142a07d5f452ca9f446be39e2c1ca04ahttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2001JCli...14.3055Krefpaperuri:(e48ae6613a7c1a8015d07ead06122668)http://adsabs.harvard.edu/abs/2001JCli...14.3055KAlthough recent El Niño events have seen the occurrence of strong intraseasonal winds apparently associated with the Madden-Julian oscillation (MJO), the usual indices of interannual variability of the MJO are uncorrelated with measures of the ENSO cycle. An EOF decomposition of intraseasonal outgoing longwave radiation and zonal wind identifies two modes of interannual variability of the MJO: a zonally stationary variation of amplitude that is unrelated to ENSO and a roughly 20°-longitude eastward extension of the MJO envelope during El Niño events. The stationary mode is represented by the first two EOFs, which form the familiar lag-correlated quadrature pair, and the eastward-extending mode is represented by the third EOF, which is usually ignored although it is statistically significant. However, the third EOF also has a systematic phase relation with the first pair, and all three should be considered as a triplet; rotating the EOFs makes the phase relation clear. The zonal shift represents about 20% of total MJO variance (which itself is about 55% of intraseasonal variance over the tropical strip). Although the eastward shift is small when compared with the global scale of the MJO, it produces a large proportional shift of MJO activity over the open Pacific, where physical interactions with ENSO processes can occur.
Kessler W. S., R. Kleeman, 2000: Rectification of the Madden-Julian Oscillation into the ENSO cycle. J.Climate, 13, 3560- 3575.10.1175/1520-0442(2000)013<3560:ROTMJO>2.0.CO;245699f178b60a7b99145753edaaa1f26http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2000JCli...13.3560Khttp://adsabs.harvard.edu/abs/2000JCli...13.3560KAn ocean general circulation model, forced with idealized, purely oscillating wind stresses over the western equatorial Pacific similar to those observed during the Madden-Julian oscillation (MJO), developed rectified low-frequency anomalies in SST and zonal currents, compared to a run in which the forcing was climatological. The rectification in SST resulted from increased evaporation under stronger than normal winds of either sign, from correlated intraseasonal oscillations in both vertical temperature gradient and upwelling speed forced by the winds, and from zonal advection due to nonlinearly generated equatorial currents. The net rectified signature produced by the MJO-like wind stresses was SST cooling (about 0.4°C) in the west Pacific, and warming (about 0.1°C) in the central Pacific, tending to flatten the background zonal SST gradient. It is hypothesized that, in a coupled system, such a pattern of SST anomalies would spawn additional westerly wind anomalies as a result of SST-induced changes in the low-level zonal pressure gradient. This was tested in an intermediate coupled model initialized to 1 January 1997, preceding the 1997-98 El Niño. On its own, the model hindcast a relatively weak warm event, but when the effect of the rectified SST pattern was imposed, a coupled response produced the hypothesized additional westerlies and the hindcast El Niño became about 50% stronger (measured by east Pacific SST anomalies), suggesting that the MJO can interact constructively with the ENSO cycle. This implies that developing the capacity to predict, if not individual MJO events, then the conditions that affect their amplitude, may enhance predictability of the strength of oncoming El Niños.
Kim S. T., J. Y. Yu, 2012: The two types of ENSO in CMIP5 models. Geophys. Res. Lett., 39, L11704.10.1029/2012GL052006b4418360ec3a2a6a6025d2d82813920bhttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2012GL052006%2Ffullhttp://onlinelibrary.wiley.com/doi/10.1029/2012GL052006/fullIn this study, we evaluate the intensity of the Central-Pacific (CP) and Eastern-Pacific (EP) types of El Niño-Southern Oscillation (ENSO) simulated in the pre-industrial, historical, and the Representative Concentration Pathways (RCP) 4.5 experiments of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Compared to the CMIP3 models, the pre-industrial simulations of the CMIP5 models are found to (1) better simulate the observed spatial patterns of the two types of ENSO and (2) have a significantly smaller inter-model diversity in ENSO intensities. The decrease in the CMIP5 model discrepancies is particularly obvious in the simulation of the EP ENSO intensity, although it is still more difficult for the models to reproduce the observed EP ENSO intensity than the observed CP ENSO intensity. Ensemble means of the CMIP5 models indicate that the intensity of the CP ENSO increases steadily from the pre-industrial to the historical and the RCP4.5 simulations, but the intensity of the EP ENSO increases from the pre-industrial to the historical simulations and then decreases in the RCP4.5 projections. The CP-to-EP ENSO intensity ratio, as a result, is almost the same in the pre-industrial and historical simulations but increases in the RCP4.5 simulation.
Knutson T. R., K. M. Weickmann, and J. E. Kutzbach, 1986: Global-scale intraseasonal oscillations of outgoing longwave radiation and 250 mb zonal wind during Northern Hemisphere summer. Mon. Wea. Rev., 114, 605- 623.07afcac80d589c1cc58642dd490826eahttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1986MWRv..114..605K/s?wd=paperuri%3A%28df9fe1a390b0380e5b763a1cd2063fae%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1986MWRv..114..605K&ie=utf-8&sc_us=8996603815436954705
Lafleur D. M., B. S. Barrett, and G. R. Henderson, 2015: Some climatological aspects of the Madden-Julian Oscillation (MJO). J.Climate, 28, 6039- 6053.10.1175/JCLI-D-14-00744.1fe9fc36708498c5418d48cd06c314d7dhttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2015JCli...28.6039Lhttp://adsabs.harvard.edu/abs/2015JCli...28.6039LNot Available
Larkin N. K., D. E. Harrison, 2005: On the definition of El Niño and associated seasonal average U.S. weather anomalies. Geophys. Res. Lett., 32, L13705.10.1029/2005GL022738e310b5b3-bec0-4fd6-b057-6e543ae87ea53ea54c0835eedec161f7d045840ba6d3http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2005GL022738%2Fcitedbyrefpaperuri:(fc1bc2b52c89e864194ad74f0ff9d71f)http://onlinelibrary.wiley.com/doi/10.1029/2005GL022738/citedbyA new NOAA definition of El Ni09o identifies a number of additional El Ni09o seasons beyond those conventionally agreed. These additional seasons are characterized by SST anomalies primarily in the western central equatorial Pacific. We show here that the seasonal weather anomalies over the U.S. associated with these additional Dateline El Ni09o seasons are substantially different from those associated with conventional El Ni09o seasons. Although some regions have similar associated anomalies, most of the major regional anomalies are quite different. Treating the two as a single phenomenon yields weaker overall seasonal weather associations and does not take advantage of the stronger associations available when the two are treated separately.
Lau K. M., P. H. Chan, 1986: The 40-50 day oscillation and the El Niño/Southern Oscillation: A new perspective. Bull. Amer. Meteor. Soc., 67, 533- 534.10.1175/1520-0477(1986)067<0533:TDOATE>2.0.CO;2b8afbeeb-3867-4823-afd2-650f564c6656ea7b1d17d4c6a9aa194ea1d16fe27e83http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1986BAMS...67..533Lrefpaperuri:(b334477b2ec77ff90d1cecfa6f9ecbe8)http://adsabs.harvard.edu/abs/1986BAMS...67..533LThe tropical Ocean-atmosphere exhibits two prominent modes of low-frequency oscillations, i.e., the "40-50" day oscillation and the El Niño/Southern Oscillation (ENSO). The two phenomena are viewed in the same perspective from 10 years of satellite-derived out-going-longwave-radiation data. Results reveal some interesting features that may lead to new insights into the understanding of the two phenomena.
Li C. Y., Y. P. Zhou, 1994: Relationship between intraseasonal oscillation in the tropical atmosphere and ENSO. Acta Geophysica Sinica, 37, 17- 26. (in Chinese)
Madden R. A., P. R. Julian, 1971: Detection of a 40-50 day oscillation in the zonal wind in the tropical Pacific.. J. Atmos. Sci, 28, 702- 708.10.1175/1520-0469(1971)0282.0.CO;23283107661179653056216429222322221870922181624324158132064393089c530a2-c983-404c-ae03-f02037a778eaa33db74c6b65a47f5bd8c4d77c78e938http%3A%2F%2Fwww.cabdirect.org%2Fabstracts%2F20093346088.htmlrefpaperuri:(3a107661c1aa7f9e6ad53ca0562d1b64)http://www.cabdirect.org/abstracts/20093346088.htmlAbstract Nearly ten years of daily rawinsonde data for Canton Island (3S, 172W) have been subjected to spectrum and cross-spectrum analysis. In the course of this analysis a very pronounced maximum was noted in the co-spectrum of the 850- and 150-mb zonal wind components in the frequency range 0.0245–0.0190 day 611 (41–53 days period). Application of a posteriori sampling theory resulted in a significance level of 656% (0.1% prior confidence level). This type of significance test is appropriate because no prior evidence or reason existed for expecting such a spectral feature. Subsequent analysis revealed the following structure of the oscillation. Peaks in the variance spectra of the zonal wind are strong in the low troposphere, are weak or non-existent in the 700–400 mb layer, and are strong again in the upper troposphere. No evidence of this feature could be found above 80 mb, or in any of the spectra of the meridional component. The spectrum of station pressure possesses a peak in this frequency range and the oscillation is in phase with the low tropospheric zonal wind oscillation, and out of phase with that in the upper troposphere. The tropospheric temperatures exhibit a similar peak and are highly coherent with the station pressure oscillation; positive station pressure anomalies are associated with negative temperature anomalies throughout the troposphere. Thus, the lower-middle troposphere appears to be a nodal surface with u and P oscillating in phase but 180° out of phase above and below this surface. Evidence for this phenomenon was found in shorter records at Kwajalein (9N, 168E) but not at Singapore (1N, 104E) or Balboa, Canal Zone (9N, 79w). We speculate that the oscillation is a large circulation cell oriented in zonal planes and centered in the mid-Pacific.
Madden R. A., P. R. Julian, 1972: Description of global-scale circulation cells in the tropics with a 40-50 day period. J. Atmos. Sci., 29, 1109- 1123.10.1175/1520-0469(1972)029<1109:DOGSCC>2.0.CO;20ad16bc86e058808314db803cb9e6916http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1972jats...29.1109mhttp://adsabs.harvard.edu/abs/1972jats...29.1109mCiteSeerX - Scientific documents that cite the following paper: Description of global-scale circulation cells in the tropics with a 40–50 day period
Madden R. A., P. R. Julian, 1994: Observations of the 40-50-day tropical oscillation- review. Mon. Wea. Rev., 122, 814- 837.
Marshall A. G., H. H. Hendon, and G. M. Wang, 2016: On the role of anomalous ocean surface temperatures for promoting the record Madden-Julian Oscillation in March 2015. Geophys. Res. Lett., 43, 472- 481.10.1002/2015GL0669841e63db220a600b2fcee88a7c7d0ecafehttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2016GeoRL..43..472Mhttp://adsabs.harvard.edu/abs/2016GeoRL..43..472MA Madden-Julian Oscillation (MJO) event dramatically amplified at the beginning of March 2015 as the convective phase traversed an unusually warm central Pacific Ocean. This record amplification also resulted in record amplitude of the MJO based on index measurements since 1974. We explore the possible role of the anomalously high ocean surface temperatures in the equatorial central Pacific for promoting the extraordinary amplification of this MJO event. Forecast sensitivity experiments with the Predictive Ocean Atmosphere Model for Australia show that the enhanced growth of the MJO resulted from amplification of the convective anomaly as it encountered the unusually warm central Pacific. Our results indicate that anomalous sea surface temperature (SST) at the onset of El Niño 2015 promoted the intensification of the MJO. We suggest a two-way interaction whereby initial SST anomalies promoted enhanced MJO activity which then possibly led to enhanced El Niño development.
Pohl B., A. J. Matthews, 2007: Observed changes in the lifetime and amplitude of the Madden-Julian Oscillation associated with interannual ENSO sea surface temperature anomalies. J.Climate, 20, 2659- 2674.10.1175/JCLI4230.1bd930db0-0482-4db8-b3b1-21edef54aa7fa359afa17bfc0968e5d12944842b20eehttp%3A%2F%2Fwww.researchgate.net%2Fpublication%2F43033212_Observed_changes_in_the_life_time_and_amplitude_of_the_madden-julian_oscillation_associated_with_interannual_ENSO_sea_surface_temperature_anomaliesrefpaperuri:(d17c66fbd54a172a1bf33f852e1a5695)http://www.researchgate.net/publication/43033212_Observed_changes_in_the_life_time_and_amplitude_of_the_madden-julian_oscillation_associated_with_interannual_ENSO_sea_surface_temperature_anomaliesAbstract The Madden–Julian oscillation (MJO) is analyzed using the reanalysis zonal wind– and satellite outgoing longwave radiation–based indices of Wheeler and Hendon for the 1974–2005 period. The average lifetime of the MJO events varies with season (36 days for events whose central date occurs in December, and 48 days for events in September). The lifetime of the MJO in the equinoctial seasons (March–May and October–December) is also dependent on the state of El Ni09o–Southern Oscillation (ENSO). During October–December it is only 32 days under El Ni09o conditions, increasing to 48 days under La Ni09a conditions, with similar values in northern spring. This difference is due to faster eastward propagation of the MJO convective anomalies through the Maritime Continent and western Pacific during El Ni09o, consistent with theoretical arguments concerning equatorial wave speeds. The analysis is extended back to 1950 by using an alternative definition of the MJO based on just the zonal wind component of the Wheeler and Hendon indices. A rupture in the amplitude of the MJO is found in 1975, which is at the same time as the well-known rupture in the ENSO time series that has been associated with the Pacific decadal oscillation. The mean amplitude of the MJO is 16% larger in the postrupture (1976–2005) compared to the prerupture (1950–75) period. Before the 1975 rupture, the amplitude of the MJO is maximum (minimum) under El Ni09o (La Ni09a) conditions during northern winter, and minimum (maximum) under El Ni09o (La Ni09a) conditions during northern summer. After the rupture, this relationship disappears. When the MJO–ENSO relationship is analyzed using all-year-round data, or a shorter dataset (as in some previous studies), no relationship is found.
Straub K. H., 2013: MJO initiation in the real-time multivariate MJO index. J.Climate, 26, 1130- 1151.10.1175/JCLI-D-12-00074.1651d5a39cf147a3a50a139c47066e2dchttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2013JCli...26.1130Shttp://adsabs.harvard.edu/abs/2013JCli...26.1130SAbstract Madden–Julian oscillation (MJO) initiation in the real-time multivariate MJO (RMM) index is explored through an analysis of observed case studies and composite events. Specific examples illustrate that both the dates of MJO initiation and the existence of the MJO itself can vary substantially among several well-known MJO indices, depending on whether the focus is on convection or circulation. Composites of “primary” MJO initiation events in which the RMM index rapidly increases in amplitude from a non-MJO state to an MJO state are presented and are supplemented by two case studies from the 1985/86 winter season. Results illustrate that, for primary MJO initiation events in the Indian Ocean (RMM phase 1), slowly eastward-propagating 850-hPa (200 hPa) easterly (westerly) anomalies over the Indian Ocean precede the amplification of the RMM index by at least 10 days, while suppressed convection over the western Pacific Ocean precedes the amplification by 5 days. These “local” Eastern Hemispheric predecessor signals are similar to those found in successive (well established) MJO events but are not captured by the global-scale RMM index because of their smaller zonal scale. The development of a primary MJO event is thus often transparent in the RMM index, since it occurs on scales smaller than zonal wavenumber 1, particularly in convection. Even when the RMM index is altered to respond to convection only, the same local precursor signals are found. Both composites and case studies suggest that, for primary MJO initiation events in the Indian Ocean, the development of global-scale circulation anomalies typically precedes the onset of large-scale deep convection.
Tam C. Y., N. C. Lau, 2005: Modulation of the Madden-Julian Oscillation by ENSO: Inferences from observations and GCM simulations. J. Meteor. Soc.Japan, 83, 727- 743.10.2151/jmsj.83.727941b6ab737c7931068431722e1e93d92http%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F130004788511http://ci.nii.ac.jp/naid/130004788511The impact of the El Nino-Southern Oscillation (ENSO) on the Madden-Julian Oscillation (MJO) is studied, based on reanalysis data and output from an ensemble general circulation model (GCM) experiment. Observed monthly sea surface temperature variations over the period of 1950-99 are imposed in the deep tropical eastern/central Pacific in the course of the SST experiment. Both GCM, and reanalysis data, indicate that intraseasonal activity of the low-level zonal wind is enhanced (reduced) over the central (western) Pacific during El Nino events. The propagation and growth/decay characterisitcis of the MJO in different phases of ENSO is also examined, based on a lag correlation technique. During warm events there is an eastward shift in the locations of strong growth and decay, and the propagation of the MJO becomes slower in the warm ENSO phase. These changes are reversed during La Nina epsiodes. Using output from the GCM experiment, the effects of ENSO on the circulation and convection during the MJO lifecycle are studied in detail. Further eastward penetration of MJO-related convection is simulated during warm events over the central Pacific. An instability index related to the vertical gradient of the moist static energy is found to be useful for depicting the onset of MJO convection along the equator. During warm events, the stronger magnitudes of this index over the central Pacific are conducive to more eastward penetration of convective anomalies in the region. These changes are mainly due to the intensified moisture accumulation at low levels. Analysis of the moisture budget suggests that the stronger moisture accumulation can be related to the increased low-level humidity over the central Pacific during warm events.
Trenberth K. E., D. P. Stepaniak, 2001: Indices of El Niño evolution. J.Climate, 14, 1697- 1701.10.1175/1520-0442(2001)014<1697:LIOENO>2.0.CO;2c49ddf9b-e9ce-41e3-86a0-38934a7332d7ef097288f9b217dc7db4cdb08c5cd402http%3A%2F%2Fwww.researchgate.net%2Fpublication%2F256476464_Indices_of_El_Nio_Evolutionrefpaperuri:(ff5364e3e0aaf688a2397f152836678b)http://www.researchgate.net/publication/256476464_Indices_of_El_Nio_EvolutionAbstract To characterize the nature of El Ni09o–Southern Oscillation (ENSO), sea surface temperature (SST) anomalies in different regions of the Pacific have been used. An optimal characterization of both the distinct character and the evolution of each El Ni09o or La Ni09a event is suggested that requires at least two indices: (i) SST anomalies in the Ni09o-3.4 region (referred to as N3.4), and (ii) a new index termed here the Trans-Ni09o Index (TNI), which is given by the difference in normalized anomalies of SST between Ni09o-1+2 and Ni09o-4 regions. The first index can be thought of as the mean SST throughout the equatorial Pacific east of the date line and the second index is the gradient in SST across the same region. Consequently, they are approximately orthogonal. TNI leads N3.4 by 3 to 12 months prior to the climate shift in 1976/77 and also follows N3.4 but with opposite sign 3 to 12 months later. However, after 1976/77, the sign of the TNI leads and lags are reversed.
Trenberth K. E., D. P. Stepaniak, and J. M. Caron, 2002: Interannual variations in the atmospheric heat budget. J. Geophys. Res.,107(D8), AAC4-1-ACC4-15.10.1029/2000JD00029785e761b36c2ec03e2142cc6dc5a02054http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1029%2F2000JD000297%2Fcitedbyhttp://onlinelibrary.wiley.com/doi/10.1029/2000JD000297/citedbyInterannual variability of the atmospheric heat budget is explored via a new data set of the computed vertically integrated energy transports to examine relationships with other fields. A case study reveals very large monthly divergences of these transports regionally with El Niño-Southern Oscillation (ENSO) and the associated changes with the Pacific-North American teleconnection pattern, and with the North Atlantic Oscillation. In the tropical Pacific during large El Niño events the anomalous divergence of the atmospheric energy transports exceeds 50 W mover broad regions for several months. Examination of the corresponding top-of-the-atmosphere net radiative fluxes shows that it is primarily the surface fluxes from the ocean to the atmosphere that feed the divergent atmospheric transports. A systematic investigation of the covariability of sea surface temperatures (SSTs) and the divergence of atmospheric energy transport, using singular value decomposition analysis of the temporal covariance, reveals ENSO as dominant in the first two modes, explaining 62% and 12% of the covariance in the Pacific domain and explaining 39.5% and 15.4% globally for the first and second modes, respectively. The first mode is well represented by the time series for the SST index for Niño 3.4 region (170°W-120°W, 5°N-5°S). Regression analysis allows a more complete view of how the SSTs, outgoing longwave radiation, precipitation, diabatic heating, and atmospheric circulation respond with ENSO. The second mode indicates aspects of the systematic evolution of ENSO with time, with strong lead and lag correlations. It primarily reflects differences in the evolution of ENSO across the tropical Pacific from about the dateline to coastal South America. High SSTs associated with warm ENSO events are damped through surface heat fluxes into the atmosphere, which transports the energy into higher latitudes and throughout the tropics, contributing to loss of heat by the ocean, while the cold ENSO events correspond to a recharge phase as heat enters the ocean. Diabatic processes are clearly important within ENSO evolution.
Weickmann K. M., G. R. Lussky, and J. E. Kutzbach, 1985: Intraseasonal (30-60 day) fluctuations of outgoing longwave radiation and 250 mb streamfunction during northern winter. Mon. Wea. Rev., 113, 941- 961.10.1175/1520-0493(1985)113<0941:IDFOOL>2.0.CO;20649d2c5-6f3e-4dd5-82c6-007364525c4d1de87b79c5f97615ae8beb72e6cc06b6http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F1985MWRv..113..941Wrefpaperuri:(5bc420765b507637ce139f81ca89d1e5)http://adsabs.harvard.edu/abs/1985MWRv..113..941WNot Available
Weng H. Y., K. Ashok, S. K. Behera, S. A. Rao, and T. Yamagata, 2007: Impacts of recent El Niño Modoki on dry/wet conditions in the Pacific Rim during boreal summer. Climate Dyn., 29, 113- 129.10.1007/s00382-007-0234-0ce13b59d-219f-46ee-8bd6-c00d07dd7bd5d8d1f09734699318f8a5bb034c67b416http%3A%2F%2Fwww.springerlink.com%2Fcontent%2Fa36w326j63468186refpaperuri:(e6a424fe52f801dc11c92e5ab8c3c6ff)http://www.springerlink.com/content/a36w326j63468186Present work uses 1979–2005 monthly observational data to study the impacts of El Ni09o Modoki on dry/wet conditions in the Pacific rim during boreal summer. The El Ni09o Modoki phenomenon is characterized by the anomalously warm central equatorial Pacific flanked by anomalously cool regions in both west and east. Such zonal SST gradients result in anomalous two-cell Walker Circulation over the tropical Pacific, with a wet region in the central Pacific. There are two mid-tropospheric wave trains passing over the extratropical and subtropical North Pacific. They contain a positive phase of a Pacific-Japan pattern in the northwestern Pacific, and a positive phase of a summertime Pacific-North American pattern in the northeastern Pacific/North America region. The western North Pacific summer monsoon is enhanced, while the East Asian summer monsoon is weakened. In the South Pacific, there is a basin-wide low in the mid-latitude with enhanced Australian high and the eastern South Pacific subtropical high. Such an atmospheric circulation pattern favors a dry rim surrounding the wet central tropical Pacific. The El Ni09o Modoki and its climate impacts are very different from those of El Ni09o. Possible geographical regions for dry/wet conditions influenced by El Ni09o Modoki and El Ni09o are compared. The two phenomena also have very different temporal features. El Ni09o Modoki has a large decadal background while El Ni09o is predominated by interannual variability. Mixing-up the two different phenomena may increase the difficulty in understanding their mechanisms, climate impacts, and uncertainty in their predictions.
Wheeler M. C., H. H. Hendon, 2004: An all-season real-time multivariate MJO index: Development of an index for monitoring and prediction. Mon. Wea. Rev., 132, 1917- 1932.ff3949520e2db3649691459062f6df4dhttp%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2004MWRv..132.1917W/s?wd=paperuri%3A%280c747c09ff298b439f3e819ddb6c0cdb%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fadsabs.harvard.edu%2Fabs%2F2004MWRv..132.1917W&ie=utf-8&sc_us=17249076170115512361
Yasunari T., 1980: A quasi-stationary appearance of 30 to 40 day period in the cloudiness fluctuations during the summer monsoon over India. J. Meteor. Soc.Japan, 58, 225- 229.825a9ed4-7b66-4971-bba8-fb164cb5310e40887e4f22e3ec3aeb9cf695d834b576http%3A%2F%2Fciteseer.uark.edu%3A8080%2Fciteseerx%2Fshowciting%3Bjsessionid%3D8EEB9A7135806F5FF0A6381AB31E33E9%3Fcid%3D9212567refpaperuri:(0013f28477ffdbfc8bf9ac6533e70190)http://citeseer.uark.edu:8080/citeseerx/showciting;jsessionid=8EEB9A7135806F5FF0A6381AB31E33E9?cid=9212567CiteSeerX - Scientific documents that cite the following paper: A quasi-stationary appearance of 30-40 day period in the cloudiness fluctuations during the summer monsoon over India
Yeh S. W., J. S. Kug, B. Dewitte, M. H. Kwon, B. P. Kirtman, and F. F. Jin, 2009: El Niño in a changing climate. Nature, 461, 511- 514.10.1038/nature08316cbeb8c90-b572-4447-b285-437cfa49917348ff6213f3ddfb718f6b8dbdaa37ea1chttp%3A%2F%2Feuropepmc.org%2Fabstract%2FMED%2F19779449refpaperuri:(8b689bbb288d5528989f50569ccb2536)http://europepmc.org/abstract/MED/19779449El Ni09o events, characterized by anomalous warming in the eastern equatorial Pacific Ocean, have global climatic teleconnections and are the most dominant feature of cyclic climate variability on subdecadal timescales. Understanding changes in the frequency or characteristics of El Ni09o events in a changing climate is therefore of broad scientific and socioeconomic interest. Recent studies show that the canonical El Ni09o has become less frequent and that a different kind of El Ni09o has become more common during the late twentieth century, in which warm sea surface temperatures () in the central Pacific are flanked on the east and west by cooler . This type of El Ni09o, termed the central Pacific El Ni09o (CP-El Ni09o; also termed the dateline El Ni09o, El Ni09o Modoki or warm pool El Ni09o), differs from the canonical eastern Pacific El Ni09o (EP-El Ni09o) in both the location of maximum anomalies and tropical-midlatitude teleconnections. Here we show changes in the ratio of CP-El Ni09o to EP-El Ni09o under projected global warming scenarios from the Coupled Model Intercomparison Project phase 3 multi-model data set. Using calculations based on historical El Ni09o indices, we find that projections of anthropogenic climate change are associated with an increased frequency of the CP-El Ni09o compared to the EP-El Ni09o. When restricted to the six climate models with the best representation of the twentieth-century ratio of CP-El Ni09o to EP-El Ni09o, the occurrence ratio of CP-El Ni09o/EP-El Ni09o is projected to increase as much as five times under global warming. The change is related to a flattening of the thermocline in the equatorial Pacific.
Yuan Y., C. Y. Li, and J. Ling, 2015: Different MJO activities between EP El Niño and CP El Niño. Scientia Sinica Terrae, 45, 318- 334. (in Chinese)
Yuan Y., H. Yang, and C. Y. Li, 2014: Possible influences of the tropical Indian Ocean dipole on the eastward propagation of MJO. Journal of Tropical Meteorology, 20, 173- 180.10.1016/j.asr.2014.02.02381bb2d29dc5cf8b0cce4205b2f241298http%3A%2F%2Fwww.cnki.com.cn%2FArticle%2FCJFDTotal-RQXB201402009.htmhttp://www.cnki.com.cn/Article/CJFDTotal-RQXB201402009.htm
Zhang C. D., 2005: Madden-Julian oscillation. Rev. Geophys.,43, RG2003.10.1029/2004RG000158579261ee1156a68aeb0437dcd3876dafhttp%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2F0471743984.vse9530%2Fabstract%3Bjsessionid%3DF7AC345CBF75EDA99EA23C2158EDCF0E.f03t02/s?wd=paperuri%3A%28237065d1f4c9d275a6c0e2d43f50b759%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fonlinelibrary.wiley.com%2Fdoi%2F10.1002%2F0471743984.vse9530%2Fabstract%3Bjsessionid%3DF7AC345CBF75EDA99EA23C2158EDCF0E.f03t02&ie=utf-8&sc_us=18130879363342324841ABSTRACT 1] The Madden-Julian Oscillation (MJO) is the dominant component of the intraseasonal (30 - 90 days) variability in the tropical atmosphere. It consists of large-scale coupled patterns in atmospheric circulation and deep convection, with coherent signals in many other variables, all propagating eastward slowly ($5 m s 脌1) through the portion of the Indian and Pacific oceans where the sea surface is warm. It constantly interacts with the underlying ocean and influences many weather and climate systems. The past decade has witnessed an expeditious progress in the study of the MJO: Its large-scale and multiscale structures are better described, its scale interaction is recognized, its broad influences on tropical and extratropical weather and climate are increasingly appreciated, and its mechanisms for disturbing the ocean are further comprehended. Yet we are facing great difficulties in accurately simulating and predicting the MJO using sophisticated global weather forecast and climate models, and we are unable to explain such difficulties based on existing theories of the MJO. It is fair to say that the MJO remains an unmet challenge to our understanding of the tropical atmosphere and to our ability to simulate and predict its variability. This review, motivated by both the acceleration and gaps in our knowledge of the MJO, intends to synthesize what we currently know and what we do not know on selected topics: its observed basic characteristics, mechanisms, numerical modeling, air-sea interaction, and influences on the El Niño and Southern Oscillation.
Zhang W. J., F. F. Jin, J. P. Li, and H. L. Ren, 2011: Contrasting impacts of two-type El Niño over the western North Pacific during boreal autumn. J. Meteor. Soc.Japan, 89, 563- 569.10.2151/jmsj.2011-510128a4e2a-9725-46cf-a6e5-529fd8d0db57eaf551f8bde5c46c0411b7d4f1efc37fhttp%3A%2F%2Fci.nii.ac.jp%2Fnaid%2F40019052112refpaperuri:(5261285a6ff448f169e4905c3f7937b8)http://ci.nii.ac.jp/naid/40019052112This work contrasts the climatic impacts of so-called warm-pool (WP) and cold-tongue (CT) El Ni09o on the atmospheric circulation over the western North Pacific (WNP). It is found that the anomalous atmospheric circulation over the WNP is nearly opposite in response to these two types of El Ni09o events in developing autumn. A weak anomalous anticyclone appears over the WNP during CT El Ni09o, whereas a weak anomalous cyclone emerges in the same region during WP El Ni09o. These nearly opposite autumn responses of atmospheric circulation have a significant impact on East Asian climate, and southern China autumn rainfall in particular, although this contrast tends to diminish as El Ni09o events enter their mature phase.