The evaluation of Kain-Fritsch scheme in tropical cyclone simulation

lkj & bl v/;;u esa 25&30 vDrwcj 1999 rd dh vof/k esa mM+hlk esa vk, egkpØokrksa ds ewY;kadu dk izfr:i.k djus ds fy, dSu fÝ’k ds diklh izkpyhdj.k ;kstuk ds lkFk ,u- lh- ,- vkj- ,e- ,e- 5 dk mi;ksx fd;k x;k gSA 25 vDrwcj 1999 ds 0000 ;w Vh lh ij 90] 30 vkSj 10 fd-eh- ds f}iFkh vk/kkfjr {kSfrt iz{ks=ksa ¼Mksesu½ okys ,u- lh- ,- vkj- ,e- ,e- 5 dks 5 fnu dh vof/k ds fy, lesfdr fd;k x;k gSA bl v/;;u ds fy, izkjfEHkd vkSj ifjlhek dh fLFkfr;ksa dks ,d va’k ds varjky ij miyC/k gq, ,u- lh- bZ- ih- ,Q- ,u- ,y- fo’ys"k.k vk¡dM+ksa ls fy;k x;k gSA ;g izfr:fir fun’kZ 954 gSDVkikLdy ij izkIr fd, x, leqnz ry ds e/; nkc vkSj 58 feuV izfr lSdaM dh vf/kdre iouksa ds lkFk mM+hlk esa vk, egkpØokr dh fodklkRed fLFkfr;ksa dks izLrqr djrk gSA bl fun’kZ ls vfuok;Z vfHky{k.kksa uker% m".k ØksM] dsanz vkSj dsanz fHkfRr izfr:i.k] gjhdsu ØksM iouksa dks izkIr fd;k x;k gSA ;g fun’kZ pØokr ds LFky Hkkx esa izos’k djus ds mijkar ml LFky ds fudV 40 ls-eh- izfrfnu dh vf/kdre o"kkZ dk iwokZuqeku yxk ldrk gS A ;g fun’kZ 24 ?kaVksa es 120 fd-eh- =qfV;ksa vkSj 120 ?kaVksa esa 0 fd-eh- dh deh ds lkFk egkpØokr ds iFk dk ,dne lgh vkdyu izLrqr djrk gSA In this study NCAR MM5 with the cumulus parameterization scheme of Kain-Fritsch is used to simulate the evaluation of Orissa Super Cyclone for the period 25-30 October 1999. The NCAR MM5 with two-way nested horizontal domains of 90, 30 and 10 km are integrated for five days starting from 0000 UTC of 25 October, 1999. The initial and boundary conditions for this study have been taken from NCEP FNL analysis data available at 1° resolution. The model simulation produces the development of the Orissa Super Cyclone with attained central sea level pressure of 954 hPa and maximum wind of 58 msec-1. The essential characteristics such as warm core, eye and eye-wall simulation, hurricane core winds were obtained by the model. The model could predict a maximum rainfall of 40 cm/day near the landfall point. The model produces a very good estimate of track with errors of 120 km at 24 hours and decreasing to 0 km at 120 hours.

Numerical prediction of the Orissa super cyclone (1999) : Sensitivity to the parameterisation of convection, boundary layer and explicit moisture processes

& ih- ,l- ;w- @ ,u- lh- ,- vkj- ,e- ,e- 5 dk mi;ksx djds mM+hlk esa 1999 esa vk, egkpØokr dh xfrfof/k;ksa vkSj mldh rhozrk ds la[;kRed iwokZuqeku dk bl 'kks/k&i= esa v/;;u fd;k x;k gSA laogu] xzgh; ifjlhek Lrj vkSj fuf’pr ueh Ldheksa dh izkpyhdj.k ;kstukvksa dh Hkwfedk dk v/;;u djus ds fy, laosnu’khyrk iz;ksx fd, x, gSaA caxky dh [kkM+h esa 90] 30 vkSj 10 fd-eh- {kSfrt varjkyksa ds rhu ikjLifjd iz{ks=ksa ¼Mksesu½ dk irk yxkus ds fy, bl ekWMy dh ifjdYiuk dh xbZ gSA ,d va’k ds varjky ij miyC/k gq, ,u- lh- bZ- ih- ,Q- ,u- ,y- vk¡dM+ksa dk mi;ksx djds izkjafHkd {ks=ksa vkSj fHkUu le; ds ifjlhek ifjorhZ rFkk 12 ?kaVs ds varjky ij leqnz lrg rkieku miyC/k djk, x, gSaA laogu] xzgh; ifjlhek Lrj vkSj fuf’pr ueh izfØ;kvksa ds laca/k esa pØokr ds ekxZ dk iwokZuqeku vkSj mldh rhozrk dh laosnu’khyrk dk v/;;u djus ds fy, rhu iz;ksx fd, x, gSaA blls izkIr gq, ifj.kkeksa ls pØokr ds ekxZ ds iwokZuqeku esa laoguh; izfØ;kvksa dh egRoiw.kZ Hkwfedk dk irk pyk gS rFkk dSu&fÝ’k 2 Ldhe ls pØokr ds ekxZ dk lcls lVhd <ax ls irk yxk;k tk ldk gSA blds vykok ;g irk pyrk gS fd xzgh; ifjlhek Lrj izfØ;k,¡ esyj&;eknk Ldhe ds lg;ksx ls lcls izpaMre pØokr dh rhozrk dks Kkr dj ldrh gSaA fuf’pr ueh izfØ;k,¡ pØokr dh xfr dks fu;af=r djrh gSa tks Hkhrjh iz{ks= ¼Mksesu½ ds 10 fd-eh- ds lw{e foHksnu ds QyLo:Ik laHko gks ldrk gSA dSu&fÝz’k 2 vkSj esyj&;eknk dh la;qDr pj.kc) ;kstuk ls pØokr ds ekxZ vkSj mldh rhozrk ds laca/kksa dks csgrj <ax ls izfr:fir fd;k x;k gSA fdlh ,dek= iz;ksx dh rqyuk esa lHkh feystqys iz;ksxksa ls pØokr ds ekxZ vkSj mldh rhozrk dk csgrj vkdyu fd;k tk ldk gSA izfr:fir pØokr esa ,diw.kZ fodflr pØokr ds] m".k ØksM] dsanz vkSj dsanz&fHkfRr tSls lHkh y{k.k ik, x, gSaA ekWMy ls izfr:fir o"kkZ forj.k vkSj rhozrk izs{k.kksa ds vuq:Ik ikbZ xbZ gSA Numerical prediction of the movement and intensification of the Orissa Super Cyclone (1999) is studied using PSU/NCAR MM5. Sensitivity experiments were made to study the role of the parameterisation schemes of convection, planetary boundary layer and explicit moisture schemes. The model is designed to have three interactive domains with 90, 30 and 10 km horizontal resolutions covering the Bay of Bengal region. The initial fields and time varying boundary variables and sea surface temperatures at 12 hour interval are provided from NCEP FNL data available at 1° resolution. Three groups of experiments were performed to study the sensitivity of the cyclone track prediction and intensification to the schemes of convection, planetary boundary layer and explicit moisture processes. The results indicate that convective processes play an important role in the cyclone track prediction and the scheme of Kain-Fritsch 2 produces the best track and the planetary boundary layer processes control the intensification with the scheme of Mellor-Yamada producing the strongest cyclone. The explicit moisture processes modulate the movement of the cyclone, which may be due to the fine resolution of the 10 km for the innermost domain. The mixed-phase scheme in combination with Kain-Fritsch 2 and Mellor-Yamada produce the best simulation in terms of the track as well as intensification. The ensemble mean of all the conducted experiments estimate the track positions and intensification better than any individual experiment. The simulated cyclone shows all the characteristics of a mature cyclone, with warm core, formation of the eye and eye wall. The model simulated rainfall distribution and intensity have good agreement with the observations.

MM5 simulation of the 1999 Orissa Super Cyclone : Impact of bogus vortex on track and intensity prediction

lkj & bl v/;;u esa 29 vDrwcj] 1999 dks mM+hlk ds rV ij vk, egkpØokr ds izfr:i.k ds fy, ,u- lh- ,- vkj@ih- ,l- ;w- ,e- ,e- 5 eslksLdsy fun’kZ ¼xzsy bR;kfn 1995½ dk mi;ksx fd;k x;k gsA bl fun’kZ esa pØokr dh izkjafHkd voLFkk vkSj mldh ifjlhekvksa dh voLFkkvksa ds :i esa jk"Vªh; e/;&vof/k ekSle iwokZuqeku dsUnz Vh- 80 ds izpkyukRed fo’ys"k.kksa dk iz;ksx fd;k x;k gS vkSj rwQku dh vof/k esa 3 fnu rd dk iwokZuqeku rS;kj djus ds fy, bl fun’kZ dks 72 ?kaVs dh vof/k ds fy, lekdfyr fd;k x;k gSA bl v/;;u dk mn~ns’; pØokr ds ekxZ ij dfYir Hkzfey ds izHkko dk ewY;kadu djuk vkSj pØokr dh rhozrk dk iwokZuqeku yxkuk gSA In this study NCAR/PSU MM5 mesoscale model (Grell et al. 1995) is used to simulate the super cyclone that struck the Orissa coast on 29th October 1999. The model makes use of the operational NCMRWF T 80 analysis as initial and boundary conditions and is integrated up to 72 hr for producing 3-day forecast of the storm. The aim of this study is to assess the impact of bogus vortex on track and intensity prediction.

Preliminary results on the simulation of the 1999 Orissa super cyclone using a GCM with a new boundary layer code

& bl 'kks/k&Ik= esa ,u- ,e- vkbZ- Vh- ,y- vkbZ- ifj;kstuk ds ,d Hkkx ds :Ik esa fy[ks x, ,d u, ,- th- lh- ,e- dksM+ ¼uker% o"kkZ½ dk mi;ksx djrs gq, mM+hlk ds egkpØokr ds izfr:i.k ls izkIr fd, x, izkjfEHkd ifj.kkeksa dks izLrqr fd;k x;k gSA bZ- lh- ,e- MCY;w- ,Q- Vh-&106 dh vkjfEHkd voLFkkvksa dk mi;ksx djrs gq, 26 vDrwcj] 1999 dks 0000 ;w- Vh- lh- ij bl izfr:i.k dks vkjEHk fd;k x;k gSA gok ds >ksadsiu ds dkjd dks lfEefyr djrs gq, ekud eksuhu&vkscw[kkso ifjlhek Lrj dksM ls Vh&80 ds foHksnu ij o"kkZ dksM dk mi;ksx djrs gq, daVªksy ju fd;k x;k gSA 78 fd-eh- xzhM varjky ls 120 LisDVªy ekWMl esa mUur {kSfrt foHksnu vkSj eUn iouksa ij u, ifjlhek Lrj ds izkpyhdj.k ls dksM vla[; o`f);ksa dks n’kkZrk gS% izfr:i.k dks vkjEHk djus ds i'pkr~ vf/kdre =qfV esa 36 ?kaVksa dh vof/k esa 350 ls 234 fd-eh-] 48 ?kaVksa dh vof/k esa 310 ls 34 fd-eh- vkSj 96 ?kaVksa dh vof/k esa 410 ls 55 fd-eh- rd =qfV;ksa dh vf/kdre deh ikbZ xbZ gSA blesa ;g lq>ko fn;k x;k gS fd bl o`f) dk Js; i`"Bh; cyksa ds mUur vkdyu vkSj u, ifjlhek Lrj cy vk?kw.kZ ¼VkdZ½ dksM esa fufgr gSA blesa cy vk?kw.kZ ¼VkdZ½ dh Hkwfedk izeq[k ;ksxnku ds :Ik esa gh gS tksfd fo’ks"k :i ls pØokrksa dh i`"B Hkwfe ls lacaf/kr gSa tgk¡ ij iousa rqyukRed :i ls gYdh gksrh gSa fdarq ml {ks= esa fo|eku i`"Bh; cy rFkk bldh vk?kw.kZ Hkqtk ¼ewesaV vkeZ½ nksuksa vf/kd gksrh gSaA vk’p;Ztud :Ik ls mPprj i`"Bh; cy u, dksM }kjk iwokZuqekfur mPprj iouksa ls Hkh mRiUu gksrs gSaA blesa jkspd ckr ;g gS fd bldh i`"B Hkwfe pØokr ds ekxZ vkSj U;wure vonkc nksuksa esa u, ifjlhek Lrj ekM;wy ls mPprj foHksnu ds dkj.k gqbZ o`f) ls cgqr vf/kd lacaf/kr gSA pØokr iFk iwokZuqeku ij vU; Hkaoj ¶yDlksa ¼laos| m"ek] vknzZrk½ ds izHkko dk ewY;k¡du djus ds fy, vkSj vf/kd fo’ys"k.k djuk vko’;d gSA We present here preliminary results from the simulation of the Orissa super cyclone using a new AGCM code (named Varsha) written as part of a NMITLI project. The simulation is initialized at 0000 UTC, 26 October 1999, using ECMWF T-106 initial conditions. The control run is made using the Varsha code at a T-80 resolution with a standard Monin-Obukhov boundary layer code incorporating a gustiness factor. With the horizontal resolution improved to 120 spectral modes with a 78 km grid spacing, and a new boundary layer parameterization at low winds, the code shows substantial improvements: the maximum error is reduced from 350 to 234 km at 36 hr after initialization, 310 to 34 km at 48 hr, and 410 to 55 km at 96 hr. It is suggested that part of the explanation for this improvement lies in the improved estimation of surface forces and torque in the new boundary layer code. The role of torque is particularly interesting as the major contribution to it comes from the outer regions of the cyclone where the winds are relatively low but the area on which the surface force acts and its moment arm are both high. Intriguingly the higher surface forces arise also from the higher winds predicted by the new code. An interesting finding is that, on both track and minimum pressure, the improvement due to higher resolution is greater with the new boundary layer module. Further analysis is necessary to assess the effect of other eddy fluxes (sensible heat, moisture) on cyclone track prediction.

Characteristic features of Orissa super cyclone of 29th October, 1999 as observed through CDR Paradip

lkj & bl 'kks/k&Ik= esa 29 vDrwcj] 1999 esa mM+hlk ds rV ij vk, egkpØokr ds Øfed fodkl ds jsMkj ls izkIr gq, vfHky{k.kksa dks izysf[kr djus dk iz;kl fd;k x;k gSA 280800 ;w- Vh- lh- vkSj 290200 ;w- Vh- lh- ds e/; fy, x, 18 ?kaVs dh vof/k ds ih- ih- vkbZ- fp=ksa ls rS;kj fd, x, /kzqoh; vkjs[kksa ds fo’ys"k.k ls bl egkpØokr ds Øfed fodkl ds jkspd igyqvksa dk irk pyk gSA bl fo’ys"k.k ls izkIr gq, izcyhdj.k ds ladsr izs{k.k dh vU; iz.kkfy;ksa ds mi;ksx ls izkIr gq, fo’ys"k.kksa ds vuq:Ik ik, x, gSaA An attempt is made to document the radar observed features of evolution of super cyclone that hit Orissa on 29 October, 1999. Analysis of polar diagrams comprising of hourly PPI images taken between 280800 UTC and 290200 UTC reveals interesting aspects of development of this Super Cyclone in terms of waxing and waning of eye size in relation to intensification process. The smallest radius of maximum reflectivity is in conformity with the colossal death toll observed close to the track of the super cyclone. Structural changes observed through radar images are in conformity with intensify changes as seen through other observing systems.

Mesoscale interactions during the genesis and intensification of October 1999 Orissa super cyclone

lkj & ;g loZfofnr rF; gS fd iw.kZ fodflr m".kdfVca/kh; pØokr esa izk;% v{klekuqikfrd lajpuk ikbZ tkrh gS tcfd pØokr ds cuus dh voLFkk esa vR;kf/kd vlaxfr fn[kkbZ nsrh gSA iz’kkar egklkxj esa gky gh esa fd, x, v/;;uksa vkSj izs{k.kksa ls ;g irk pyk gS fd m".kdfVca/kh; pØokrksa dh mRifRr dk irk yxkkus esa eslksLdsy dh ijLij fØ;k,sa egRoiw.kZ Hkwfedk fuHkk ldrh gSaA m".kdfVca/kh; pØokr dh mRifRr ds vk/kqfud fl)kar Hkh mi;qZDr iwoZdfFkr rF; ij vk/kkfjr gSaA bl 'kks/k&Ik= esa vkbZ- vkj- mixzg ls izkIr foEckoyh vkSj cM+s iSekus ij Hkzfeyrk ds {ks=ksa dk fo’ys"k.k izLrqr fd;k x;k gSA ftuesa ;g ns[kk x;k gS fd 1999 esa mM+hlk esa vk, egkpØokr dh Hkh izkjfEHkd voLFkkvksa esa eslksLdsy ls pØokr ds coaMj dh ijLij fØ;kvksa dk irk yxk gSA It is well known that a mature tropical cyclone is known to have a nearly axisymmetric structure but that the formation stage exhibits considerable asymmetry. Recent studies and observations in the Pacific indicate that mesoscale interactions could play an important role in the genesis of tropical cyclones. Modern theories of tropical cyclone genesis are also based on this premise. In this paper, an analysis of the IR satellite imagery and large scale vorticity fields is presented, which shows that mesoscale vortex interactions occur in the early stages of the 1999 Orissa super cyclone also.

Numerical experiments for improvement in mesoscale simulation of Orissa super cyclone

& 29 vDrwcj] 1999 dks mM+hlk ds rV ij vk;k egkpØokr mM+hlk ds vc rd ds bfrgkl dk lcls izpaM rwQku Fkk ftldh 250 fd-eh- izfr ?kaVk dh rhoz xfr okyh iouksa us jkT; ds 12 rVh; ftyksa dks rgl&ugl dj MkykA rwQku ds LFky ls Vdjkus ds i'pkr~ 36 ?kaVs ls Hkh vf/kd le; rd iouksa dh izpaMrk cuh jghA bl rwQku ls tku eky dk dkQh uqdlku gqvkA yxHkx 10]000 yksxksa dh tkusa xbZA bl v/;;u esa rwQku ds eslksLdsy izfr:Ik dks csgrj cukus ds fy, dqN egRoiw.kZ igyqvksa dh tk¡p gsrq O;kid la[;kRed iz;ksx fd, x, gSaA bu igyqvksa esa xSj nzoLFkSfrd xfrd] fun’kZ {kSfrt foHksnu vkSj egRoiw.kZ izR;{k izfØ;kvksa ds izkpyhdj.k 'kkfey gSaA rwQku dk 5 fnolh; izfr:Ik ¼123 ?kaVksa ds yxkrkj lekdyu½ rS;kj djus ds fy, eslksLdsy fun’kZ ,e- ,e- 5 dk mi;ksx fd;k x;k gSA blesa le:ih foHksnu ¼30 fd-eh-½ vkSj le:ih le; J`a[kyk ds lkFk nzoLFkSfrd ¼,p-,l-½ rFkk xSj nzoLFkSfrd ¼,u- ,l-½ xfrdksa ds lg;ksx ls rwQku ds izfr:i esa xSj nzoLFkSfrdrk ds izHkko dh tk¡p dh xbZ gSA bl fof/k ls rwQku vkSj fo’ks"k :Ik ls bldh rhozrk dk xSj nzoLFkSfrd xfrdksa ds lkFk lgh izfr:i.k gksrk gSA xSj nzoLFkSfrd xfrdksa ds lkFk 90 fd-eh-] 60 fd-eh- vkSj 30 fd-eh- ds foHksnuksa ij rwQku dk izfr:i.k djrs gq, fun’kZ dh laof/kZr {kSfrt foHksnu dh egRrk dh tk¡p dh xbZ gS vkSj rwQku ds izfr:i.k esa bldk izR;{k izHkko ns[kk x;k gSA egRoiw.kZ izR;{k izfØ;k okys diklh laogu xzgh; ifjlhek Lrj ¼ih- ch- ,y-½ vkSj fofdj.k gsrq fun’kZ esa miyC/k izkpyhÑr ;kstukvksa ds csgrj lEHkkO; leUo; dk irk yxkus ds fy, la[;kRed iz;ksx Hkh fd, x,A lh- lh- ,e- 2 fofdj.k izkpyhÑr ;kstuk lesr xzsy diklh laogu vkSj gk¡x&isu ih- ch- ,y- ;kstuk ds lkFk leUo;u okyh ;kstuk ds vU; ijhf{kr ;kstukvksa dh rqyuk esa lcls csgrj ifj.kkeksa dk irk pyk gSA The super cyclone that crossed Orissa coast on 29 October 1999 was the most intense storm in the history of Orissa with 12 coastal districts of the state were battered by winds reaching 250 kmph. The fury of winds continued for more than 36 hours after landfall of the storm. The storm caused huge damage to properties and nearly 10,000 people lost their lives. In the present study, extensive numerical experiments are conducted to investigate some important aspects that may lead to the improvement in mesoscale simulation of the storm. The aspects that are addressed here include non-hydrostatic dynamics, model horizontal resolution and parameterization of important physical processes. The mesoscale model MM5 is used to produce 5-day simulation of the storm. The influence of non-hydrostaticity is investigated by simulating the storm with hydrostatic (HS) and non-hydrostatic (NS) dynamics at same resolution (30 km) and with same time step. The storm, in particular its intensity is better simulated with non-hydrostatic dynamics. The importance of increasing model horizontal resolution is investigated by simulating the storm at 90 km, 60 km and 30 km resolutions with non-hydrostatic dynamics and found to have perceptible impact in simulation of the storm. Numerical experiments also are conducted to find the best possible combination of the parameterization schemes available in the model for the important physical processes cumulus convection, planetary boundary layer (PBL) and radiation. The combination of Grell cumulus convection and Hong-Pan PBL scheme along with CCM2 radiation parameterization scheme is found to provide the best result compared to the other schemes tested.