Current status of tropical cyclone track prediction techniques and forecast errors

Abstract

lkj & fiNys dqN n’kdksa esa HkweaMyh; m".kdfVca/kh; pØokrksa ds iwokZuqeku esa gksus okyh =qfV;ksa esa mUur vk¡dM+k laxzg.k rduhdksa] lrr ekWMy fodkl] mPp foHksnuksa vkSj Hkzfey fof’"Vrk ds QyLo:Ik dkQh deh vkbZ gSA ;g ns[kk x;k gS fd lewps fo’o esa iwokZuqeku dh =qfV;ksa esa izR;sd le; ds vuqHkoksa ds vk/kkj ij izfro"kZ 1 ls 2 izfr’kr rd dh deh vkbZ gS ftuds ifj.kkeLo:Ik yEch vof/k ¼48 ?kaVs ls vf/kd½ ds iwokZuqekuksa esa vR;ar rhoz xfr ls lq/kkj gks jgk gSA vVykafVd vkSj iz’kkar egklkxj tSls csfluksa esa ;|fi fofHkUu dkj.kksa ls iwokZuqeku dh =qfV;ksa esa dkQh vf/kd deh gqbZ gS rFkkfi Hkkjrh; {ks= esa ;g izo`fŸk dkQh lk/kkj.k jgh gSA bl {ks= esa iwokZuqeku dh =qfV;ksa esa deh vkus dk ,dek= dkj.k Hkkjr ekSle foKku foHkkx ¼Hkk- ekS- fo- fo-½ vkSj jk"Vªh; e/;e vof/k ekSle iwokZuqeku dsUnz ¼,u- lh- ,e- vkj- MCY;w- ,Q-½ tSls izpkyukRed ,u- MCY;w- ih- dsUnzksa }kjk muds {ks=h; vkSj HkweaMyh; ekWMyksa ds fo’ys"k.k esa la’ysf"kr Hkzfeyrk dk vf/kdkf/kd iz;ksx gks jgk gSA varZjk"Vªh; m".kdfVca/kh; pØokr vuqla/kku esa bl rF; ij vc vf/kd cy fn;k tk jgk gS fd fo’ks"k :Ik ls cgqr de le; esa gh vikjEifjd vk¡dM+ksa ds vf/kd mi;ksx] eslksLdsy fo’ys"k.kksa] Hkzfey fof’k"Vrk ds fy, la’ysf"kr vk¡dM+ksa ds mi;ksx ls vkSj mPp ekWMy foHksnu esa HkkSfrd izkpyhdj.k ds fu"iknu }kjk m".kdfVca/kh; pØokr ds ekxZ dk iwokZuqeku vf/kd lVhd cu ldsA pØokrksa ds ySaMQkWy ds laca/k esa igys ls py jgh gjhdsu MCY;w- vkj- ,Q- ifj;kstuk ij fo’ks"k :i ls py jgs vuqla/kku vkSj izpkyukRed dk;ksZa ls vkus okys o"kksZa esa Hkkjrh; {ks= dks ykHk gksus dh laHkkouk gSA rFkkfi] Hkkjrh; {ks= }kjk ekWMy ds fodkl ds lefUor iz;klksa ds vykok ekWMy ds fo’ys"k.k ds fy, ikjEifjd vkSj vikjEifjd vk¡dM+ksa dh vf/kdre miyC/krk rFkk mUur vk¡dM+k laxzg.k rduhd ds mi;ksx dks vf/kd izkFkfedrk nh tkuh pkfg,A

Thanks to advanced data assimilation techniques, continuous model development, higher resolutions, and vortex specification, there has been considerable progress in the reduction of global tropical cyclone forecast errors during past few decades. It has been observed that world-wide rate of reduction of forecast errors was of the order of 1%-2% per year for all time horizons, with most rapid improvement at longer durations (beyond 48 hours). While other basins like Atlantic and Pacific oceans reported greater rate of decline of these errors due to various factors, the trend has been quite modest for Indian region. The only factor responsible for reduction of errors in the region was the greater use of synthetic vortex by operational NWP centres like India Meteorological Department (IMD) and National Centre for Medium Range Weather Forecasting (NCMRWF) in their Regional & Global model analyses. The current emphasis of international tropical cyclone research is to achieve greater accuracy of TC track prediction, especially in the short range, by maximizing the use of non-conventional data, meso-scale analysis, use of synthetic data for vortex specification, and the performance of physical parameterization at higher model resolution. The current research and operational emphasis of the ongoing  Hurricane WRF project for land falling cyclones, is expected to benefit the Indian region in the years to come. Nevertheless, the Indian region needs to assign higher priority to the greater availability of conventional & non-conventional data and use of advanced data assimilation technique for model analysis besides its concerted efforts on model developments.