Outline of the talk A life cycle of a strong subtropical stratospheric intrusion during June 2014 influence reduce the intensity of Indian rainfall after onset. Analysis of all monsooon breaks days during 29 years (1979-2007) (Breaks days from Rajeevan et al., 2010) Propose a hypothesis on “Linkages of Stratospheric Intrusion with deficit Indian rainfall” Suvarna Fadnavis and Rajib Chattopadhyay, J. Clim, 2017
Background Ramasw swam amy (1962) 62) has propose osed d that the e intrusion rusion of the e mid latitu tude de trough gh may trigge ger monso nsoon on deficit cit rainf nfall l over er the e Indian dian region ion and lead d to developmen elopment of break eak monso nsoon on condition. ndition. Mapes and d Zui uidem dema (1996); 96); Al Allen n et et al., , (2009) 09) deline ineate e invasion sion of dry y air from om sub ubtr tropi opica cal l up upper r tropos posphe phere re with th tropi pica cal l drou ought ghts. s. Krishna shnan n et et al., (2000) 000) have e attri ribut buted ed monso nsoon on brea eaks ks to an abrup upt t movem emen ent t of anoma omalous lous Rossb sby waves es origina ginati ting ng from om Bay of Beng ngal al travelin eling g into o north thwest t and centra ntral l India. dia. Suvarna Fadnavis and Rajib Chattopadhyay, J. Clim, 2017
Deficit rainfall over India during June 2014 Suvarna Fadnavis and Rajib Chattopadhyay, J. Clim, 2017
Data a and Analysis ysis ERA-Interim Reanalysis data: Potential Vorticity (PV) temperature winds ozone relative humidity (RH) Indian summer monsoon rainfall (ISMR) from India Meteorological Department Diagnostic Analysis: Bivariate Probability Distribution Function (BPDF) of the two variables (PV and rainfall) Specific humidity (q) (vertically averaged between 400hPa-200hPa) Vertical wind shear (i.e. difference in zonal winds (U) at 200hPa minus 850 hPa) Temperature anomaly (departure from climatology) index (Tanom_diff_index), (i.e. temperature anomaly at 200 hPa minus 850 hPa) Kinetic energy at 200 hPa (ke200 i.e. U*U)
Ver ertica ical di distrib ibut ution ion of Potenti ential Vorti tici city ty (PV) 10 Jun une e 12 2 Jun une e 14 Jun une e 16 Jun une e 18 18 Jun une PV PV 10 Jun une e 12 Jun une e 14 Jun une e 16 Jun une e 18 18 Jun une PV PV Eddy Ed y shading ding from om the e RWB B over er the e Tibeta tan n Platea eau
Rossb sby wave br e brea eakin ing g in in the e subtr tropica opical l Jet et (PV-35 350K) 0K) 10 Ju June e 12 Jun une e 14 4 Ju June 16 Jun une e 18 18June ne 20 0 Jun une PV Rossby wave breaking in the jet migration of extra-tropical stratospheric PV (>2) over the Tibetan Plateau
Rossby Wave Breaking (RWB) at 370 K 10 June 12 June PV 14 June 16 June 20 June 18 18 June Westward eddy shedding associated with RWB Suvarna Fadnavis and Rajib Chattopadhyay, J. Clim, 2017
Intrusion of dry and ozone-rich air 10 June 12 June 14 June 16 June 18 June Ozone In the UT RH < 30% RH 10 June 12 June 14 June 16 June 18 June
Cold air intrusion over the Tibetan Plateau RWB event associated with cold intrusion over the Tibetan Plateau from extra- tropics. Cold air persisted for the rest of month - June 2014. Suvarna Fadnavis and Rajib Chattopadhyay, J. Clim, 2017
Intrusi rusion on of co cold and dr dry air r : Implications plications on stat atic ic stabili ability ty Stratosphe ospheric ric in intrusi usion 10 10 Ju June ne 2014 col cold air and and dry in in th the UT UT for or rest est of of the the mon month th Increa ease se in in stati tic stabil ability ty may lead to to monso soon on break. Suvarna Fadnavis and Rajib Chattopadhyay, J. Clim, 2017
Lin inkag kages of stratosp ospheric eric in intrusion ion wit ith Indi dian r rain infall l 6 7 IMD Precipitation Temp central India 6 5 PV at 200 hPa Temp Tibetan Plateau 5 AIRS OLR 4 Normalized Anomalies 4 3 3 2 2 1 1 0 0 -1 -1 -2 -2 -3 -3 6/1/2014 6/8/2014 6/15/2014 6/22/2014 6/29/2014 Time (month/day/year) Stratospheric PV negative anomalies in temperature over TP and CI high OLR negative anomalies in rainfall Suvarna Fadnavis and Rajib Chattopadhyay, J. Clim, 2017
Stratosp osphe heri ric c Intr trusions usions dur uring ng mons onsoo oon n break ak days ( 1979-2007 ) (a) Region-1 (27°N-35°N, 60°E-78°E) (b) Region-2 (27°N-35°N, 78°E-110°E). Bivariate Probability Distribution Function (BPDF) is negatively skewed, indicating a likelihood of deficit monsoon during stratospheric intrusions (PV>2). It indicates that subtropical stratospheric intrusions near the Indian region may be one of the factors influencing ISMR deficit .
Hy Hypoth pothesi esis: s: Link nkag ages es of strat atosph ospheric eric intrus usion ion with th Indian dian rainf infal all l de defici icit t (a) (b) Suvarna Fadnavis and Rajib Chattopadhyay, J. Clim, 2017
Balloo loonson nsonde de measureme surement nts s at Nainital nital, , India ia (Aug ugust ust 2016) Collabor aborat ation ion: IITM, TM, Pune, ETH, Zurich, h, DWD German any, ARIES ES, Nainit ital al Fadnavis et al., 2017
Thank you ! suvarna@tropmet.res.in
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