Abstract
Improved understanding of underlying mechanism responsible for Indian summer monsoon (ISM) droughts is important due to their profound socio-economic impact over the region. While some droughts are associated with ‘external forcing’ such as the El-Niño and Southern Oscillation (ENSO), many ISM droughts are not related to any known ‘external forcing’. Here, we unravel a fundamental dynamic process responsible for droughts arising not only from external forcing but also those associated with internal dynamics. We show that most ISM droughts are associated with at least one very long break (VLB; breaks with duration of more than 10 days) and that the processes responsible for VLBs may also be the mechanism responsible for ISM droughts. Our analysis also reveals that all extended monsoon breaks (whether co-occurred with El-Niño or not) are associated with an eastward propagating Madden–Julian Oscillation (MJO) in the equatorial Indian Ocean and western Pacific extending to the dateline and westward propagating Rossby waves between 10° and 25°N. The divergent Rossby wave associated with the dry phase of equatorial convection propagates westward towards Indian land, couple with the northward propagating dry phase and leads to the sustenance of breaks. Thus, the propensity of eastward propagating MJO during boreal summer is largely the cause of monsoon droughts. While short breaks are not accompanied by westerly wind events (WWE) over equatorial western Pacific favorable for initiating air–sea interaction, all VLBs are accompanied by sustained WWE. The WWEs associated with all VLB during 1975–2005 initiate air–sea interaction on intraseasonal time scale, extend the warm pool eastward allowing the convectively coupled MJO to propagate further eastward and thereby sustaining the divergent circulation over India and the monsoon break. The ocean–atmosphere coupling on interannual time scale (such as El-Niño) can also produce VLB, but not necessary.
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References
Annamalai H, Slingo J (2001) Active/break cycles: diagnosis of the intraseasonal variability over the Asian summer monsoon. Clim Dyn 18:85–102
Annamalai H, Sperber KR (2005) Regional heat sources and the active and break phases of boreal summer intraseasonal (30–50 day) variability. J Atmos Sci 62:2726–2748
Duchon CE (1979) Lanczos fitering in one and two dimensions. J Appl Meteorol 18:1016–1022
Dunkerton TJ, Baldwin MP (1995) Observation of 3–6 day meridional wind oscillations over the tropical Pacific, 1973–1992: horizontal structure and propagation. J Atmos Sci 52:1585–1601
Gadgil S, Asha G (1992) Intraseasonal variation of the summer monsoon. I: Observational aspects. J Meteor Soc Japan 70:517–527
Gadgil S, Joseph PV (2003) On breaks of the Indian monsoon. Proc Ind Acad Sci Earth Planet Sci 112:529–558
Goswami BN (1998) Interannual variation of Indian summer monsoon in a GCM: external conditions versus internal feedbacks. J Clim 11:501–522
Goswami BN (2005) South Asian Monsoon. In: Lau WKM, Waliser DE (eds) Intraseasonal variability in the atmosphere–ocean climate system, Chap. 2, pp 19–61
Goswami BN, Shukla J (1984) Quasi-periodic oscillations in a symmetric general circulation model. J Atmos Sci 41:20–37
Goswami BN, AjayaMohan RS (2001) Intraseasonal oscillations and interannual variability of the Indian summer monsoon. J Clim 14:1180–1198
Gruber A, Kruger AF (1984) The status of the NOAA outgoing longwave radiation dataset. Bull Am Meteor Soc 65:958–962
Kalnay E, co-authors (1996) The NCEP/NCAR 40-year reanalysis project. Bull Am Meteor Soc 77:437–471
Kemball-Cook S, Wang B (2001) Equatorial waves and air–sea interaction in the Boreal summer intraseasonal oscillation. J Clim 14:2923–2942
Kripalani RH, Kulkarni A, Sabade SS, Revadekar JV, Patwardhan SK, Kulkarni JR (2004) Intraseasonal oscillations during monsoon 2002 and 2003. Curr Sci 87:325–331
Krishnamurti TN, Ardanuy P (1980) The 10–20 day westward propagating mode and breaks in the monsoon. Tellus 32:15–26
Krishnamurti TN, Subrahmanyam D (1982) The 30–50-day mode at 850 mb during MONEX. J Atmos Sci 39:2088–2095
Krishnan R, Zhang C, Sugi M (2000) Dynamics of breaks in the Indian summer monsoon. J Atmos Sci 57:1354–1372
Krishnan R, Mujumdar M, Vaidya V, Ramesh KV, Satyan V (2003) The abnormal Indian summer monsoon of 2000. J Clim 16:1177–1194
Krishnan R, Ramesh KV, Samala BK, Meyers G, Slingo JM (2006) Indian Ocean–monsoon coupled interactions and impending monsoon droughts. Geophys Res Lett 33:L08711. doi:10.1029/2006GL025811
Kumar KK, Rajagopalan B, Hoerling M, Bates G, Cane M (2006) Unraveling the mystery of Indian monsoon failure during El-Niño. Science 314:115–119
Lau KM, Chan PH (1986) Aspects of the 40–50 day oscillation during the northern summer as inferred from outgoing longwave radiation. Mon Wea Rev 114:1354–1367
Lawrence DM, Webster PJ (2002) The boreal summer intraseasonal oscillation: relationship between northward and eastward movement of convection. J Atmos Sci 59:1593–1606
Madden RA, Julian PR (1971) Detection of a 40–50 day oscillation in the zonal wind in the tropical Pacific. J Atmos Sci 28:702–708
Madden RA, Julian PR (1972) Description of global-scale circulation cells in the tropics with a 40–50 day period. J Atmos Sci 29:1109–1123
Madden RA, Julian PR (1994) Observations of the 40–50-day tropical oscillations—a review. Mon Wea Rev 122:814–837
Mujumdar M, Kumar V, Krishnan R (2006) The Indian summer monsoon drought of 2002 and its linkage with tropical convective activity over northwest Pacific. Clim Dyn 28:743–758. doi:10.1007/s00382-006-0208-7
Rajeevan M, Bhate J, Kale JD, Lal B (2006) High resolution daily gridded rainfall data for the Indian region: analysis of break and active monsoon spells. Curr Sci 91:296–306
Ramamurty K (1969) Some aspects of the “Break” in the Indian southwest monsoon during July and August. Forecasting manual FMU report No. IV-18.3
Raman CRV, Rao YP (1981) Blocking highs over Asia and monsoon droughts over India. Nature 289:221–223
Ramaswamy C (1962) Breaks in the Indian summer monsoon as a phenomenon of interaction between easterly and the subtropical westerly jet streams. Tellus 14:337–349
Rasmusson E, Carpenter T (1982) Variations in tropical sea surface temperature and surface wind fields associated with the Southern Oscillation/El-Niño. Mon Wea Rev 110:354–384
Reynolds RW, Rayner NA, Smith TM, Stokes DC, Wang W (2002) An improved in situ and satellite SST analysis for climate. J Clim 15:1609–1625
Rodwell MJ (1997) Breaks in the Asian monsoon: the influence of southern hemispheric weather systems. J Atmos Sci 54:2597–2611
Rui H, Wang B (1990) Development characteristics and dynamic structure of tropical intraseasonal convection anomalies. J Atmos Sci 47:357–379
Saith N, Slingo J (2006) The role of the Madden–Julian oscillation in the El-Niño and Indian drought of 2002. Int J Climatol 26:1361–1378
Sajani S, Beegum N, Krishna Moorthy K (2007) The role of low-frequency intraseasonal oscillations in the anomalous Indian summer monsoon rainfall of 2002. J Earth Syst Sci 116:149–157
Salby ML, Hendon HH (1994) Intraseasonal behavior of winds, temperature and convection in the tropics. J Atmos Sci 52:2207–2224
Shukla J (1987) Interannual variability of monsoons. In: Fein JS, Stephens PL (eds) Monsoons, Chap. 14.
Sikka DR (1980) Some aspects of the large-scale fluctuations in the planetary and regional scale circulation parameters. Proc Ind Acad Sci Earth Planet Sci 89:179–195
Sikka DR, Gadgil S (1980) On the maximum cloud zone and the ITCZ over Indian longitudes during the southwest monsoon. Mon Wea Rev 108:1840–1853
Singh SV, Kripalani RH, Sikka DR (1992) Interannual variability of the Madden–Julian oscillations in Indian summer monsoon rainfall. J Clim 5:973–978
Smith TM, Reynolds RW (2004) Improved extended reconstruction of SST (1854–1997). J Clim 17:2466–2477
Uppala SM, Kallberg PW, Simmons AJ, Andrae U, a Bechtold V, Fiorino M et al (2005) The ERA-40 re-analysis. Quart J Roy Meteor Soc 131:2961–3012
Walker GT, Bliss EW (1932) World weather. Mem R Meteorol Soc 4:53–84
Walker GT (1933) Seasonal weather and its prediction. Brit Assoc Adv Sci 103:25–44
Wang B (2005) Theory. In: Lau WKM, Waliser DE (eds) Intraseasonal variability in the atmosphere–ocean climate system, Chap. 10, pp 307–360.
Wang B, Rui H (1990) Synoptic climatology of transient tropical intraseasonal convection anomalies: 1975–1985. Meteorol Atmos Phys 44:43–61
Webster PJ, Yang S (1992) Monsoon and ENSO: selectively interactive systems. Quart J Roy Meteor Soc 118:877–926
Wheeler M, Kiladis GN (1999) Convectively coupled equatorial waves: analysis of clouds and temperature in the wavenumber-frequency domain. J Atmos Sci 56:374–399
Wu MC, Schubert SD, Suarez MJ, Pegion PJ, Waliser DE (2006) Seasonality and meridional propagation of MJO. J Clim 19:1901–1921
Xavier PK, Goswami BN (2007) A promising alternative to prediction of seasonal mean all India rainfall. Curr Sci 93:195–202
Yasunari T (1980) A quasi-stationary appearance of 30–40 day period in cloudiness fluctuations during the summer monsoon over India. J Meteor Soc Japan 58:225–229
Acknowledgments
One of the authors, Susmitha Joseph, wishes to acknowledge the Council of Scientific and Industrial Research (CSIR) for financial support. Susmitha Joseph is also thankful to Dr. M. S. Madhusoodhanan for providing the code for space-time spectrum analysis and Dr. Matthew Wheeler for helpful discussions and suggestions. The authors are thankful to the two anonymous reviewers for their valuable comments.
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Joseph, S., Sahai, A.K. & Goswami, B.N. Eastward propagating MJO during boreal summer and Indian monsoon droughts. Clim Dyn 32, 1139–1153 (2009). https://doi.org/10.1007/s00382-008-0412-8
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DOI: https://doi.org/10.1007/s00382-008-0412-8