Long term climatology and trends of heat waves over India during the recent 50 years (1961-2010)

Abstract

lkj & bl 'kks/k i= esa Hkkjr dh eq(; Hkwfe ds 103 LVs'kuksa ls xzhe _rq ¼ekpZ ls tqykbZ½ ds nkSjku ds foxr 50 okksZa ¼1961&2010½ ds A.k ygj ;k yw ds vkidM+ksa dk mi;ksx djrs gq, A.k ygjksa ¼HWs½ rFkk vfr A.k ygjksa ;k Hkhk.k yw ¼SHWs½ ds fofHkUu lkaf(;dh; igyqvksa tSls fd nh?kZ vof/k tyok;q) n'kdh; fofo/krk vkSj nh?kZ vof/k izofr;ksa dh tkip dh xbZ gSA A.k ygjsa @ Hkhk.k A.k ygjsa ,sUlks ¼ENSO½ ls tqM+h gSa tks fo'o ds ekSle dks izHkkfor djrh gS) mldh Hkh ;gki tkip dh xbZ gSA ,slk ik;k x;k gS fd ns'k ds vusd Hkkxksa ¼mRrj) if'peksRrj) e/; vkSj iwokZsRrj izk;}hi½ esa izR;sd _rq esa vkSlru 8 ;k mlls de A.k ygjksa okys fnuksa esa A.k ygjsa eglwl dh xbZA ns'k ds mRrj) if'peksRrj vkSj e/; Hkkxksa esa eq(; :i ls Hkhk.k A.k ygjksa dk vuqHko fd;k x;k gSA fiNys pkj n'kdksa dh rqyuk esa vHkh gky ds n'kd 2001&2010 ds nkSjku lewps ns'k esa A.k ygjksa @ Hkhk.k A.k ygjksa okys fnuksa dh la(;k esa c<+ksrjh ns(kh xbZ gS tks ns'k vkSj HkweaMy ds fy, Hkh lcls vf/kd xeZ n'kd jgk gSA bl fo'ysk.k vof/k ds nkSjku Hkkjr esa A.k ygjksa okys fnuksa esa egRoiw.kZ :i ls c<+ksrjh dk :(k ns(kk x;k gSA mRrj if'peksŸkj rFkk e/; Hkkjr ds yxHkx 25 LVs'kuksa ds vkidM+s A.k ygjksa okys fnuksa esa egRowi.kZ :i ls c<+ksrjh ds :(k dks n'kkZrs gSa vkSj if'peksŸkj Hkkjr ds 5 LVs'ku Hkhk.k A.k ygjksa okys fnuksa esa egRoiw.kZ :i ls of) ds :(k dks n'kkZrs gSaA ;|fi dqN LVs'kuksa ij A.k ygjksa okys fnuksa ¼mRrj Hkkjr ds 2 LVs'ku rFkk iwohZrV ds 3 LVs'ku ij½ vkSj Hkhk.k A.k ygjksa okys fnuksa ¼iwohZrV ds 2 LVs'ku ij½ esa egRoiw.kZ :i ls fxjkoV dh izofRr ns(kh xbZ gSA lkekU;r% A.k ygjksa@Hkhk.k A.k ygjksa okys fnuksa dh ckjackjrk) LFkkf;Ÿko vkSj vkoRr {ks= vyuhuksa okksaZ ds ckn ds okksaZ ¼vyuhuksa +1½ ds nkSjku vkSlr ls vf/kd ik, x, gSaA ABSTRACT. Using HW information of 103 stations from Indian main land during the hot weather season (March to July) for the last 50 years (1961-2010), various statistical aspects of heat waves (HWs) and severe heat waves (SHWs) such as long term climatology, decadal variation, and long term trends were examined. The link of HWs/SHWs with ENSO phenomena, which has known impact on the weather world over was also examined. It was observed that many areas of the country (north, northwest, central and northeast Peninsula) have experienced HW days of ≥8 HW days on an average per season. The SHW were mainly experienced over north, northwest and central parts of the country. Compared to previous four decades, there was noticeable increase in the HW/SHW days over the country during the recent decade 2001-2010, which is also the warmest decade for the country as well as for the globe. Significant long term increasing trends in HW days was also observed over India during the analysis period. About 25 stations from north, northwest and central India showed significant increasing trend in the HW days and 5 stations mainly from northwest India showed significant increasing trend in SHW days. However, few stations have shown significant decreasing trend in HWs (2 stations from north India & 3 stations from east coast) and SHWs (2 stations from east coast). In general, the frequency, persistency and area coverage of the HW/SHW days were found to be more than average during years succeeding El Nino (El Nino +1) years.