Operational use of improved CMVs derived from INSAT IR data in NWP Model over Indian region

Abstract

Lkkj & balSV ls izkIr lh- ,e- oh- dh xq.krk vk’oklu ¼D;w- ,-½ tk¡p izkjaHk esa ,u- lh- bZ- ih- okf’kaxVu vFkok bZ- lh- ,e- MCY;w- ,Q- ls izkIr 12 ?kaVs ds fuEu foHksnu iwokZuqeku ds vk¡dM+ksa dk mi;ksx djds dh tkrh gSA fgan egklkxj ds vi;kZIr vk¡dM+ksa okys {ks= ls balSV vFkok vU; mixzgksa ls izkIr lh- ,e- oh- dk mi;ksx bu iwokZuqekuksa esa izkjaHk esa ugha fd;k tkrk FkkA vU; dsUnzksa dks balSV ls izkIr lh- ,e- oh- dh xq.krk fo’oluh; Lrj dh ugha yxhA tqykbZ 98 ls igys] balSV ds vykok fdlh vU; mixzg ls fgan egklkxj ds vi;kZIr vk¡dM+ksa okys {ks= ds vk¡dM+s izkIr ugha gq,A tqykbZ 98 esa] ehfVvkslSV&5 dks fgan egklkxj ds Åij 63 fMxzh iwoZ dh vksj f[kldk;k x;kA balSV ekSle foKku vk¡dM+k lalk/ku ra= ¼vkbZ- ,e- Mh- ih- ,l-½ esa balSV ls lh- ,e- oh- izkIr djus dh izpkyukRed ;kstuk esa dqN egRoi.kZ lq/kkj fd, x, ftlls mi;ksxdrkZvksa dks csgrj xq.krk  ds mixzg ls izkIr iou ds vk¡dM+s miyC/k djok, tk ldsaA la’kksf/kr ,yxksfjFe esa xq.krk vk’oklu tk¡p esa ,y- ,- ,e- iwokZuqeku dk mi;ksx fd;k x;k gSA LiSDVªe dh 'khr ifjf/k ij es?kksa  ds dqN izfr’kr ds vkSlr rkieku ds vk/kkj ij nkc vkSj m¡pkbZ;k¡ fu/kkZfjr dh tkrh gSaA balSV vkSj ehfV;kslsV&5 ls izkIr lh- ,e- oh dk foLrkj ls rqyukRed v/;;u fd;k x;k gSA  balSV vkSj ehfV;kslsV-5 ls izkIr ifj"Ñr lh- ,e- oh- ds chp xq.krk ds vk/kkj ij vPNh vuq:irk dk irk pyk gSA vfHkufr vkSj vkj- ,e- ,l esa Hkh lq/kkj gq, gSaA lh- ,e- oh- esa igys izsf{kr {ks=h; iouksa esa Hkh lq/kkj gqvk gSA ehfV;kslsV&5 dh rqyuk esa balSV ls izkIr lh- ,e- oh- dh de la[;k dk dkj.k balSV jsfM;ksehVj dk fuEu LFkkfud foHksnu gSA fp=ksa ds f=d ls rS;kj lh- ,e- oh- ds nks lSVksa dks lfEefyr fd;k x;k ftlesa nks lSVksa esa LFkkfir lh- ,e- oh- dks 'kkfey ugha djus dk  /;ku j[kk x;k gSA balSV  ls izkIr ifj"Ñr lh- ,e- oh- ls ekWMy }kjk fd, tkus okys iwokZuqeku ij ldkjkRed izHkko iMk gSA

Earlier Quality Assurance (QA) tests of INSAT derived CMVs were done using low resolution 12 hour forecast from NCEP Washington or ECMWF. These forecasts earlier did not use satellite derived CMVs from INSAT or other satellites from data sparse Indian Ocean. Other centers did not find INSAT CMVs of reliable quality. Before July 1998, no other satellite except INSAT covered the data sparse Indian Ocean. In July 1998, METEOSAT-5 was shifted over Indian Ocean at 63 degree East. Certain vital changes have been incorporated in the operational scheme of INSAT CMVs derivation at INSAT Meteorological Data Processing System (IMDPS) for providing satellite derived winds of improved quality to the users. The modified algorithm uses LAM forecast in QA tests. Pressures and heights are assigned on the basis of mean temperature of certain percentage of cloud population at the cold end of the spectrum. Detailed comparison of CMVs from INSAT and METEOSAT-5 has been done. The improved CMVs from INSAT and METEOSAT-5 show quite good agreement qualitatively.  The bias and RMS also show improvements. Zonal winds observed earlier in CMVs have shown improvement. The lesser number of INSAT CMVs is due to lower spatial resolution of INSAT radiometer compared to METEOSAT-5. The two sets of CMVs generated from triplet of images are being combined, taking care of excluding the collocated CMVs in the two sets. The improved INSAT derived CMVs have shown positive impact on the Model forecast.