Advance forecasting of cyclone track over north Indian Ocean using a global circulation model

Abstract

&  m".kdfVca/kh; pØokr lewps fo’o esa vf/kdka’k rVorhZ {ks=ksa esa xaHkhj vkSj fodjky Mj mRiUu djrs jgrs gSaA blfy, m".kdfVca/kh; pØokrksa ds laca/k esa vf/kd lVhd vkSj yEch vof/k ds iwokZuqeku dh ek¡x c<+rh tk jgh gSA ;|fi dkQh le; ls lhfer {ks= fun’kZ ¼,y- ,- ,e-½ m".kdfVca/kh; pØokrksa ds xfrdh; iwokZuqeku ds fy, ijEijkxr lk/ku jgs gSa fQj Hkh bl ckr ls Hkh badkj ugh fd;k tk ldrk gS fd pØokrksa dh xfrdh; izÑfr ds izLrqrhdj.k esa HkweaMyh; ifjlapj.k fun’kkZsa ¼th- lh- ,e-½ ds mi;ksx ds Qy Lo:Ik dkQh lq/kkj vk;k gSA mnkgj.k ds fy, caxky dh [kkM+h ds dqN pØokr rks caxky dh [kkM+h esa gh fodflr gksrs gSa fdarq cgqr ls pØokr [kkM+h ds iwoZ dh rjQ cus fuEu nkc {ks= ds l?ku gksus vkSj [kkM+h dh vksj c<+us ds dkj.k curs gSa ftlls ;g Li"V gS fd pØokr ds iwokZuqeku ds fy, pØokr ds mRiUu gksus ds foLr`r {ks= dks 'kkfey djus dh vko’;drk gSA bl 'kks/k&i= esa geus crk;k gS fd ,y- ,- ,e- vkSj th- lh- ,e- dh la;qDr fo’ks"krk rqyukRed :Ik ls uohu Js.kh ds HkweaMyh; ekWMyksa ¼th- lh- ,e-½ ls pØokr ds ekxZ vkSj mldh rhozrk tSls dqN vR;ar egRoiw.kZ y{k.kksa  ds laca/k eas yEch vof/k ds vkSj vf/kd lVhd rjg ds iwokZuqeku nksuksa miyC/k djk ldrs gSaA lkr pØokrksa ls lacaf/kr fofHkUu LFkkuksa] _rqvksa] o"kZ vkSj mudh rhozrk] izfr:fir ekxksZa vkSj pØokrksa ds ySaMQky ds LFkyksa ds ik¡p fnuksa ls Hkh vf/kd le; igys dh mudh vkjafHkd voLFkkvksa vkSj muds laca/k esa leqnz lrg rkieku ¼,l- ,l- Vh-½ ds ekfld tyok;q foKku ds 48 ?kaVs igys tkjh fd, x, gSaA buesa rkRdkfyd izpkyukRed iwokZuqeku ds leku gh =qfV;k¡ ikbZ xbZ gSaA

Tropical cyclones pose a serious and growing threat to many coastal areas world over; there is increasing demand for better accuracy as well as longer range for tropical cyclone forecasts. While the traditional tool for dynamical forecasting of tropical cyclones has been Limited Area Models (LAM), there are reasons to believe that use of Global Circulation Models (GCM) may result in improved representation of cyclone dynamics. Over Bay of Bengal, for example, while some cyclones develop in situ, many result from intensification of low pressure system that travel from the east, implying need for consideration of a large domain. We show here that a relatively new class of Global Circulation Models (GCM), combining the advantages of LAMs and GCMs, can provide both longer range and better accuracy for such critical parameters like track and intensity. For seven cyclones representing different locations, seasons, years and strength, simulated tracks and land-fall locations show, with initial condition more than 5 days ahead and only monthly climatology of sea surface temperature (SST), errors comparable to those from current operational forecast 48 hours in advance.