Operational weather forecasting using data from Automatic Weather Stations and other modern observing systems - Case study of tropical cyclone Jal 2010

Abstract

vc rd ftu LFkkuksa ls ekSle laca/kh ?kaVsokj vk¡dMs+ miyC/k ugha gks ikrs Fks vc Hkkjr ekSle foKku foHkkx ls mixzg ds vk/kkj  ij Lopkfyr ekSle LVs’kuksa ¼AWS½ ds laLFkkiu ds dkj.k ;s vk¡dM+s izkIr gksus yxs gSa vkSj bu vk¡dM+ksa dk cgqr egRo gSA izpkyukRed ekSle iwokZuqeku ds fy, bl izdkj ds ,- MCY;w- ,l- ls izkIr fd, x, vk¡dM+ksa dh laHkkfor mi;ksfxrk fo’ks"kdj ml le; cgqr vf/kd gksrh gS ftl le; pØokrh rwQku tSlh ekSle dh izfrdwy fLFkfr;k¡ gksrh gSaA bl 'kks/k i= esa] caxky dh [kkM+h esa 4&8 uoEcj] 2010 dh vof/k esa m".kdfVca/kh; pØokr ¼TC½ tky ds cuus rFkk mlds psUuSa ds mRrjh Hkkx dks ikj djus ds ekeys dk v/;;u fd;k x;k gSA blesa eq[;r% Hkkjrh; izk;}hi ds nf{k.kh {ks= esa ,- MCY;w- ,l- ls izkIr fd, x, vk¡dM+ksa dk mi;ksx fd;k x;k gSA blesa tky dh rhozrk dk fu/kkZj.k djus esa vk¡dM+ksa dh mi;ksfxrk dks crk;k x;k gSA 7 uoEcj] 2010 dks 1800 ;w-Vh-lh- ds vklekl JhgfjdksVk ¼SHR½ ds fudV tky ds LFky izos’k ds LFkku dks mPp iou xfr vfHkys[k] psUuS esa MkWIyj ekSle jsMkj ¼DWR½ ds mRiknksa rFkk dYiuk&1 mixzg ls izkIr mPp foHksnu okys fp=ksa tSls vU; vk/kqfud midj.kksa ls izkIr dh xbZ lwpukvksa dks lglacaf/kr djrs gq, mldk lgh <ax ls irk yxk;k x;k gSA lS)kafrd :i ls O;qRiUu vuqikfrd fLFkjkad  ¼ds-½ dk mi;ksx djrs gq, pØokr okys {ks= esa nkc dh deh vkSj vf/kdre iouksa dks vkdfyr fd;k  x;k gSA psUuaS ds mRrj esa fLFkr ,Uuwj canjxkg esa yxs ,- MCY;w- ,l- }kjk vfHkysf[kr fd, x, iou xfr ekuksa dk mi;ksx djrs gq, Hkw&LVs’ku esa izsf{kr fd, x, vf/kdre iouksa dk Ik;kZoj.kh izokg] mlds vkxs c<+us dh fn’kk vkSj ?k"kZ.k ds izHkko dk fo’ys"k.k fd;k x;k gSA leqnz esa pØokr dh iou xfr dh laHko U;wu lhek dks vkdfyr fd;k x;k vkSj ;g lR;kfir fd;k x;k fd 7 rkjh[k dks 0600 ;w-Vh-lh- ij pØokrh rwQku ds :Ik esa Vh- lh- tky ls dh xbZ izpkyukRed ?kks"k.kk lgh FkhA

 The hourly meteorological data available from hitherto unrepresented locations due to the installation of satellite-based Automatic Weather Stations (AWS) by India Meteorological Department are valuable.  The potential utility of data from such AWS for operational weather forecasting is tremendous, particularly during adverse weather situations like that of a cyclonic storm.  In this paper, a case study of the Tropical Cyclone (TC)  Jal which formed during the period 4-8 November, 2010 over Bay of Bengal and crossed north of Chennai has been undertaken mainly by utilising data from AWS in the southern Indian peninsula. Utility of the data in assessment of the intensity of Jal has been explained. The landfall location of Jal near Sriharikota (SHR) around 1800 UTC of 7^th November, 2010 could be pinpointed using wind and hourly pressure data correlated with inputs from other modern equipments like the High Wind Speed Recorder, products from Doppler Weather Radar (DWR) at Chennai  and high resolution imageries from Kalpana-1 satellite. The pressure defect and maximum winds in the cyclone field have been computed by using a theoretically derived proportionality constant (K). An analysis on the effect of environmental flow, direction of movement and friction on the maximum winds observed in a land station has been made using the wind speed values  recorded by AWS at Ennore Port located  north of Chennai.  The possible lower bound of wind speed of the cyclone while out at sea has been computed and verified that the operational declaration of the TC Jal as a cyclonic storm at 0600 UTC of 7^th was  correct.