bluuebunny/crossref_metadata_2025 huggingface dataset:
Some aspects of the West African monsoon circulation As deduced from a geostationary satellite
Authors: JEGEDE OLUWAGBEMIGA  O.
Published: January 2022

This paper focusses on some aspects or the West African monsoonal circulation observed during the period 15 July-l0 August 1979 of the PGGE, as derived from the satellite cloud windvectors. Temporal averages of the computed winsfields reveal that the flow at the low level is southerly (monsoonal), and Its line of discontinuity with the continental northeasterly was found at approximately 16°-18°N, lying about 300 km south of the accepted mean position. At both the middle and upper tropospheres the flow is easterly with axis about 12o-14,N and, latitude 8 No respectively, such that it is a circulation south of the axis and northwards, it is anticyclonic. The satellite-observed tropospheric circulation IS then discussed in relation to the, weather manifestations over the sub-region typical of the July / August period.

 

The mass fields obtained from our gridded satellite-winds indicate that inflow into the land area occur mainly at the lowest layer (1000:850 hPa), whereas at the upper, levels (that is, above 850 hPa) it is predominantly an outflow, The tropospheric average gives a net mass for divergence from within the area, The significance of this result in relation to the observed weather phenomenology of a temporary cessation of the monsoon precipitations occurring about the peak of the season IS also discussed.
A creeping and surface breaking long strike-slipfault inclined to the vertical in a viscoelastic half space
Authors: SEN SANJA Y , SARKAR SEEMA , MUKHOPADHYAY ARABINDA
Published: January 2022

An asoismically creeping surface-breaking strike-slip fault inclined to the vertical at an arbitrary angle, situated in a simple model of the lithosphere-asthenosphere system consisting of a visoelastic half space is considered. The exact solutions for displacements, stresses and strains In the model are obtained. Computed results show that the inclination of the fault has a significant influence on the values of the displacements, stresses and strains. The rate of accumulation of shear stress tending to cause strike-slip movement has been found to be greatest for vertical strike-slip fault, while for faults inclined at smaller angles to the horizontal, this rate is significantly smaller. The uses of such theoretical models in obtaining greater insight into the earthquake processes in seismically active regions and their relations to the dynamics of the lithosphere-asthenosphere system are examined.
Climatological study of the cyclonic storms crossing the east coast of India
Authors: GANESAN G. S. , MUTHUCHAMI A. , SUKUMAR E. R.
Published: January 2022

Us ~n ~ Poisson distribution the probabil.ity of cyclonic storms crossing each latitude stripon the cast coast of India In a month In a random to-year period l'i com puted and presented in the raper. v ariouscharacteristics of the cyclonic systems such as average speed of movement s, average life spa n and the averagedistan ce travelled alon gwith the coefficient s uf variation before and after crossing the coast are examined anddiscussed here.
Tibetan anti cyclone as simulated in a general circulation model
Authors: Dash S. K.
Published: January 2022

The a im of this study is \0 investiga te the sensitivity of the mean posit ion and intensity ofthe T ibetan anticyclon e simula ted in a Gener al Circ ula tion Model (GeM) to presc ri bed sur face bou nda ry conditions. Results of some numerica l experiments show tha t the intensity and position of the anticyclo ne a rc influencedby the global sea surface temperat ures. The simulated Ti betan High is close 10 its climatologicalla titudi na l positiondur ing monsoon mon ths when the seasonal var iations in the surfac e bo un dary co ndi tions a re introdu cedand the model i.;, integrated from the initia l atmospheric conditions co rrespo ndi ng 10 winte r.
Non-uniform dissipation of the Antarctic ozone hole
Authors: KANE R.P.
Published: January 2022

The evolution o f the Antarct ic ozone hole is illustrated fo r 1985·1989 and 1990 springs.A detailed study for 1986.19 89 and 1990 events indicates that the evolution. which occurs in ea rly October . isfairly unifo rm over the South Pole. Hence the fluctuations observed at Syowa, McMurdo and Palmer duringthis period arc mostly due to the vortex \''3.11 passing in and out over these periferial loca t ions. However, later inNovember when the hole is dissipating, the vortex may shift from the South Pole in any direction and may alsocome back or intensify on Sou th Pole before finally disappearing. At South Pole. the recovery started by Octoberend in 19S5. 19R6 and 1988 but later in 19R7 (November end), 1989 {November beginning) and 1990 (Novemberend •.
Usability of the low frequency mode in southwest monsoon circulation for long range prediction of rainfall activity over central India
Authors: SUBRAMANIAN S. K. , JOSHI U. R.
Published: January 2022

pro pagation have been ctudicd on the hasi, of upper air data of a few sta tions,The frequency of occurrence Ill' significant periodicity in th is mode i.. rchuively high for Visakhapatnam andMadras. 1 here appears a large inter-annual variability of the maximum amplitudes of rhe filtered series with nospecial preference to any latitudinal bell. Northward propagation of this mode also slums large inn.....-annunlvarisbility. In some ~ears the propaga tion " as totally absent. The phusc changes in the filtered ser ies o fVisakbapnma rn match ed with the cha nges in weekly ra infall activity over central India and thi.. may, pcrhups.be used to foreshadow the activ ity of the monsoon over central India ,
Characteristics of quasi-biennial oscillation over Kenya and their predictability potential for the seasonal rainfall
Authors: OGALLO L.J . , OKOOLA R. E. , WANJOHI D. N.
Published: January 2022

investigated using monthly zo.ta l wind com ponents from Nairob i (Kenya ) within the period1966-1987. RelatiHn.;;hips between the stra tospher ic eas terl y and westerly wino phases and t he seasona l ra infallanomalics were also iO\t,"..')t igatN.Res ults Irom spec tra l a nalysis indicated tho d ominance (If a 28 mon th s' period in the IllOal w ind comnoncn.The \'Crtical ra te of propagar ioa of both westerly and easterly wind phases was about - · 1.2 kmmonth.Results from statist ical analysis indicated signitica nr (at 5 '~~ level) association between rainfall anomalyclass (above normal. normal. a mi below normal) and east erly and westerl y wind phas...es.
A simple model to estimate air temperature and soil temperatures under vertisol
Authors: DAS H. P. , PUJARI A. D. , CHOWDHURY A.
Published: January 2022

Hnscd on a truncated s ine curve and exp onential fu nction models. diu rnal cha nges in airand soil temperat ures have I:....'en estima ted during day and night hours respect!....el..·. Each model uses o nlv fo urparameters. viz.. maximum a nd mini mum temperature at va rious levels. the lime ()f sunset and durat ion t;f da ylnight length. The models. when a pplied to experimental as well as independent dat a sets, were fo und to givereasonably accu rate estimates for a n>' lime of the day an d night except between I·B O1ST and sunset at the gro undsurface.
On the use of entropy in Markovian model of rainfall
Authors: MUKHOPADHYAY S. K.
Published: January 2022

A statistical study of the annual rainfall data at Cocch Behar district during the periodt90 1 to t9S ~ has been undertaken by using. Markov chain model. One step 3 X3 Ma rcov chain model has beenused in (his study. The outcomes of the model reveal normal, bad and good year of rainfall a t the two stationsof thi s district. The hypoth esis of independence has been tested on the use of entropy and it has been ver ifiedusing likelih ood ra tio criterion. The results of the two methods are the same-tha t the yearly rainfall occurrencemay be regarded as independent at the two places o f the district.
Reaction of radiometric parameters to atmospheric pollution: Part I - Variation over time
Authors: DESIKAN V. , CHIVATE V. R. , ABIHYANKAR V. V.
Published: January 2022

The drive for indust rial development h... ... 100 to large scale urbanisation and result,.-. d in theinjec tion of good amount of suspended particle.. and gaseous substances into the atmosphere. The m..er-abuscof the capac ity .of the atmosphere to sustain the equilibrium is bound to disturb the heal budget of the earthatmospheresystem. Radiometric parameters of the atmosphere give an early indication of the trends in the longtermclimatic changes. Whi le the global rad iant exposure is no t likely to show perceptible changes due to theincreased scauering by the pollutants, I ~ ~ diffuse radiant el(p(ls~re and the direct so.l3! irradianc~ respond qu icklyto the changes In the atmospheric conditions. Various controlling factors like humidity. soi l moist ure and cloud"have d ifferent effects on the terres trial radiant energy and the changes in thi s energy OI..'Cur slowly and ta ke longtime to affect the climate at a place. But the general trend is indicated by the increased diffuse component in thedi rect sola r rrmdiances and in the net outgoing terrestrial radia nt energy. The responses arc clearly indicative.part icularly ,II Punc......here the industrial activiti es grew at a phenomenal rate during the past fifteen years.
Simulation of the thermodynamic structure of atmospheric boundary layer over Calcutta with a one-dimensional TKE closure PBL model
Authors: RAM PARASHU , VENUGOPAL T. , MOHANTY U. C.
Published: January 2022

The thermodynamic structure of boundary la)l:r over Calcutta on the eastern secto r of the monsoontrough has been exam ined byint~ratina I one-dimensional TKE closure planetary bound ary laye r model fortropics which inJcudes interaction oCclo udiness and radiation with turbulence and counter , radient transports ofheal moistu re and momentum. Data sets cf pilct-esperiment phase ofMONTBLEX in 1988 have been used formispurpo se. two specific situations, o ne 'When liquid water is present and the other ~tlcn very strona: winds are prevailinain the boundary layer 8~ considered. Diurn al varialion oCturbulent kinetic ener'ly.lhe TKE budget and the veelicalprofiles otTKE and eddy exchange coefficient ha ve revealed the importance DC counter gradient transports notonly aCheat and moisture but also oC momentum. Combined role DC presence of liquid water and counter gradientsin buoyant production and role of counter a:radienu of momentum in shear production have beenestablished.
Perturbations in upper tropospheric easterlies and Bay cyclones
Authors: GUPTA G. R. , CHAND RAMESH
Published: January 2022

Pertu rbat ions in th e form of large amplitude troughs or dosed circu lation s are absen ted todevelop in the weak upper tro posph eric easterlies at 200 and 100 hPs levels over no rthwest Pacific am! adjoiningIndi an Ocean. Occasionally, these are 2 to 3-C colder than their immediate enviro nme nt. These systems areobserved 10 propagate downwards durina their westwa rd tr aversal : while ove r 500 h Ps th ese in teract with andactivate the lower troposph eric cyclonic circ ula tion to intensify into a depression/cyclonic stem}. At this stage, thecyclonic:ci rcu l" tion in upper tropo sph eric levels is observed 10 vanish: this may, however. re-appear subseq uently onfUl1ho r int ensification of the cyclonic sto rm . Evidence of such interaction a nd intensification is adduced with a fewt)'pica) synoptic systems .
PRESSURE FIELDS OVER INDIAN SEAS AND THEIR RELATIONSHIPS WITH INDIAN SUMMER MONSOON RAINFALL
Authors: SINGH O. P. , JOSHI S. P. , SUNDARI G.
Published: January 2022

Monthly ano mal ies of surface pressu re for quadrangula r grids over Indian Seas ha ve been computedulilisin& 15 )'~ars' I NCU data (1976-90). The relationships between the grid pressure anomalies and summermonsoon rainfall over India ha ve beendiscussed. Good correlations have bee n found between the anomalies ofMayand the monsoon rainfall.
VARIATIONS IN PRECIPITABLE WATER CONTENT IN LOWER TROPOSPHERE AT PUNE DURING SUMMER MONSOON
Authors: PARASNIS SURENDRA S.
Published: January 2022

Variation. in Precipitable Water Content (pWC) at Pune (lse32'N. 73·S1'E..ssg m u 1)duri ngIUmmer mon aoon aealOM of 1980 and 1981. have been studied. Spectrum of PWC values in layen 9OQ..650 bPashowed peals at period. 2-3 and '·8 days. The periodicities observed in PWC ~comparable with these observed. in other mckorolOlical parameters.
REACTION OF RADIOMETRIC PARAMETERS TO ATMOSPHERIC POLLUTION : PART II -A COMPARATIVE STUDY BETWEEN PAIRS OF STATIONS
Authors: DESIKAN V. , CHIVATE V. R. , ABHYANKAR V. V.
Published: January 2022

In part1,the effect ofatmosphe ric pollution overtime at a ai"-e n location \\'3$ discussed.The parriculate mat ter generated O"U a place is dispersed to surrounding areal> Thus II comp arative stud)'between pain ofstation s is worthwhil e. The effect of indust rial activi ty is clearly seen in the case of New Delhi when compared toJodhpur. However, the changes are not h~ly sienificanl in the case cfihe already de veloped areas like AhmedabadAnd Calcutta. Almost all statio ns show 8 decreasing trend in the net QUlgoina terrestrial radiant ent'rlf)'.
STRANGE AT TRACTOR DIMENSION OF SURFACE RADIO REFRACTIVITY OVER INDIAN STATIONS
Authors: SRIVASTAVA H. N. , RAY K. C. SINHA , BHATTACHARYA S. N.
Published: January 2022

1 , ~1 1 1t: th e Ih 1.....I)· of tldr-n n i ni... ric ...h no s, th e r.h til l n: fml,'llvit)" hil s been \ llh ti l'\ t for l'i ~1 1 1r.' I'l l".'l\lali\'l" suuions in 1IIlI ia a n J l1iKU:-" 1.'11i n relat ion to st rn age ut truc to r dimcnsto n. It .....;,.. found th a t SL'( to n iner .Hl.IIlWlt"l", nrc nee..h·,1 10 p redict r.tJiu refracti vity OWl the Ind ian region similar lu tluu re pone..t Iur other" l l1 l ll ~ I'I l\' n ;; phe n. uuvuu ALso. inl a n d an d .;tH!<; la l stati ons ca nno t lll.' gll lllp\' d in i clut icu to th eir cli ma tic features" ~, , , · , i , 11.,,', al du ueu..ion
VARIABILITY OF INDIAN SUMMER MONSOON : RELATIONSHIP WITH GLOBAL SST ANOMALIES
Authors: VERMA R. K.
Published: January 2022

(iloh,tlcurr("!,1111111 ll111p .o; uflhe SlIllll1lt" r mUn!\4 lOn prt>cipil:lliull anomalies a nti St"a SU l f.IC(" Tt"mpt"1 a1lln"' (SST) a nUllul!it'.'i are pTt'St'IlI("d . n lir1 ) -)l' /u (1950..1479) rime St' 1; ("S uf 11l0n...nnn ind("x b co rn' l a h~d ....; Ih Iht"SST tillll' Sl'riCS al t"nch 1° ;<2° latitLIl1co! u nl:iluJt" box uf th t" \\(1(111 (>I,:eans usi ng COADS (Comprehensive O..:eanAllno...pl1("fl." Dala S('1)dn ta ttl "3riOUS timc IJgs o f lUonth s (i.t' .. l1luI11 h,'S of year s p recedi ng 'lI1.1 conc urrcnI lu Ihe1ll011Stllll1-)l'at) , Ctl lTclal ion..mups :'I ll' pn.-pUTl,.f 111111 Illaly"I'" 1(1 i.lclltify Il' IN."Oll lle ct it ln "-' Ilf llln ll....oon pTt'I,:ipilp t' S o f inlt"raetjuns .....ith Ihe munsoun. The first on e, .... h il.:h sho ws pmili\'c <:orre lnlio n of summermonsoon pf('\.-ipililtion anoll1alit"s ",i lh Ihe ct"nlral and l":Jsl ..-mequaturial P1Sthat lhe monsoon which follo ws abmlt a )'t'lir la ll'r ur tX'currence ofwaml t"pisode of EI..Nin~Suut hem Oscillatiun (ENSO) is generally ....-eltc It is also suggestetJ Ihal this inleract io n might be taki ng placelhruugh Ihe in llue nce or nOr1h em hemisp here int er tempera tures. Th e seco nd I)-PC of inleraclion of equ alorialPaci fic SST ....i lh mon soon is revealed through the strung n~al ive co rrela tio ns bqinning befo re lh e summer monsoon an d continuing ....; lh g~ a l er magnitud e an d o~ r ....i der extent. suuest ing th ai a .....arm SST anomaly j ust precedineanll concurrent to monsoon ~aso n weaken s th e monsson.AiNt"li intcf<n'lions bctween Ihe Indian Ocean and monsoon are also emph a si ~d in the anal ysis. Two key~ginns are ide nt ified. Th e cen tra l Indian Ocun south o f th e equalor shoW!strong positive corre la tions during (helalt' no n hl'm ",inler a nd spring. Th e other key Tq!'ion is in the north Ind ian Geran. Th e correlations are significanllynt'ga li\'e. Some teleconnections with th e Atlantic basin are also revealed which are ralhe rdifficuh to explain but ma yfind usefu l ap plications in monitoring and long-range forecas line of the monsoon.
PLANETARY BOUNDARY LAYER STRUCTURE IN THE MONSOON TROUGH REGION
Authors: TYAGI A. , MOHANTY U. C. , RAMESH K. J.
Published: January 2022

A ~IUt ly of PbllWIHI") lt cundury l.nycr (PUll in the lIIunsllun llflllgh !"l'l:illll ha:oo h! 't'11 Carrl,'t11l1l1based on MONTDl EX 1989 pilot experiment d ata PilI. structure over land !>hllw'IO lAid l' , pati,11 lIn,1 tem poralvariatums. TIlrCCtypes of PRL- .'IOha llu\oli convective . monsoon ~11111 111) convective boundaryl a yers haw been obv-rved. Ch ar act eri st ic features :I!I:"Ul"i:JI~lt wilh Jill"t'relll types of POL have been iJe- l\lilit... 1and p rcscnr c..t in th e p:Jlll'r.With the help of observe...1rill ,structure over-eastern. ceutral and wcsrcm M'11m suf llu' ll1tlll~ IHn tmullii. ;1111"'1111'1hash«'11 made to develop "PlIl '(" e ro s e-sec tio ns of PUL UH'r Ind o -G a ngetic plains llu rilli' act ive. wcuk ,lilt' bren kmonsoon co nd itio n s.
INFLUENCE OF DEW ON THE GROWTH AN YIELD OF WHEAT CROP
Authors: CHOWDHURY A. , DAS H. P. , SINGH S. S.
Published: January 2022

In Ihi.-.l>1U.1Yt"lItXI uf .tt"w'lrlll.H.i l..sun th e i:fll" ,h cycle ofwheat and its yield h ave bee n examinedfur sh .o.c,.lt'l1l'.1 ~\tH~i ll1:'l·ml.;nllloc41linns in Ind ia. viz.. I IIsar. Gwalior, Vuran nsi. Jab alpur. Raipur and Pune. The d at a"'t"t varied Imm I ~ III 15 years.TIl e" JOlla we re MJb;.·..:h~·11 11l Fb hc r's tec h niq ue and pe riods when dew exe n ed beneficialor baneful effect . iJt"1I1iliC'.1.TIl(' SIIIlI)' iudicmea th at dew i!t'ncraJl) helps th e emergence ofwheat. De wfall from jointinglul1l1wt'rin1!A1uul!'h Sl"~(, helps in proper dt'w lup lllt" ni ofthe plllni und increase in yield . Subject ing lilt' dat atopnlh OIlull)si... h lulIght out h igh associntiou betw een relative h umidit y and );t"IJ . II also revealed th at, h y and large.dew l l i rrl 'll)' ur indirectly contritnues In inc rease wheat yield .
FORMATION OF TROPICAL CYCLONES IN THE BAY OF BENGAL
Authors: GANESAN G. S. , MUTHUCHAMI A. , SUKUMAR E. R.
Published: January 2022

of Rengal. For th is purpose, the Ilay of Bengel is divided into number of one degree lat itud eIOlljlilUJcsqua re- crib and the Ic rmetion prob abilities WMe found in each of these cells in different months of bestmonsoon an ti pre-monsoon 30 th et il will help in formul ation of long term plan for the natura l d isa ster redu crion.Ino rde r 10 lind OUI the la titud inal variation offhe formation o rcyclonic stonns. the Bay o( Btnaal is aaain d ivided into(our sectors with a wi dth o f S-d ("~rte lo ngitude sectors. namely. 80-85. 85-90, 90-9S and 9SoI00. In (hue sectors themeanloca tion s of'fonnation in terms of'Iatitude was ca lcula ted and discussed . Furt her, the Bay is sub-divided into 14division s 10 lin.t out the possible spa tial va ria lions using sta tisl ical lech niques.Th e cause c f these spa tial vari ation isals o discu ssed .
ON ASPECTS OF UPDRAFTS IN .LOCAL SEVERE STORMS: A CONTROL THEORETIC APPROACH
Authors: DHAR P. K. , SINHA D. K.
Published: January 2022

In th is pa per. an <e ltO li pt is mad e to app ly a co ntrol theo retical app roach 10 study 1M optimumd istrib ut ion of .vcrM,(' thermal b4 10}mh.-Y (th ermal enere)-). requi red for attainment of maximum ¥mal velocity inftu" llr~lr.afl . llli, dr,·f'1n ('lnu."nl. hmikall)' 8 transport P"~U. is Uln..titionn.l by the constraint. pullin, Slipul.tion on,tu-'"",,1h uf .il' "("raae powrr iC'nt'facN b ) ' therm al boo)...,,,")' durilll the lime of cperatloe. The vaJkle lion h as bunsoullin Oil the lin~ f ~!'IsJer ."'... or U !'lin~ data. nUl .....tloll)" divorced frum realil)',
TERRESTRIAL RADIANT ENERGY EXCHANGES ACROSS TROPOPAUSE OVER PUNE
Authors: DESIKAN V. , JAYARAMAN K. , BHAGWAT S.P.
Published: January 2022

Fort nightly auuusphe ric sound ings """ilh radiomete r are bei ng made al Pu ne after th e sunset Thedam obtained o ver an (" iih t yea r pe riod. 1978-1985 an d on occasions ....'hen th ese so unl.Hnis reac hed stratosp hereh aw bee n studied in o rde r 10 obta in a pictu re of th e terr estri al radiant ene rgy excha nges (infrared rad iative !luxexchanges) Berms the tropopause. It is Iound th ai th e tropopause .:ene raJly loses energy almust th rough out the yearexceru du ring the monso on period . Th e net lo ss in rad iant euC' rgy by the tropo pause is 1.4Wm - ~. Th e losses in th epre-monsoo n and th e post -monsoon pe riod s are respectivel y 3.4 Wm - =an d 41 Wrn - ~ . whereas the gai n du ring th emonsoon .'Il!'IIS(ln is 5.2 Wm - : . Winh' r losses amo um rc 6.ft Wm - ~ , These valu es. however, vary wide ly in individualca ses depc nding upon th e sky cover. ROl l the d epth nf water vapo ur ..:o lumo .
Understanding biosphere-precipitation relationships: Theory, model simulations and logical inferences
Authors: SUD Y.C. , LAU K. M. , WALKER G. K. , KIM J. H.
Published: January 2022

The four major biophysical controls of vegetation which govern land-atmosphere interaction emanate from the ability or vegetation to. (a) evapotranspire (b) trap solar radiation within leaf organizations. (c) regulate evapotranspiration by stomatal control and (d) modify (generally increase) the surface roughness on the scale of turbulent eddies, Simulation studies with General Circulation Models together with a few observational analyses have provided a rational understanding of vegetation-precipitation interaction. In studies with artificially enhanced vegetation-related processes a strong dependence of rainfall on vegetation has been inferred. For Sahelian and other tropical desert-border regions, where evapotranspiration is small, increasing the surface-albedo (desertification) decreases rainfall. When evaportranspiration and or land-surface roughness are increased in some selected regions - a potential effect of vegetation an increase in local rainfall is produced. The above effects both individually and jointly have simulated increased monsoon rainfall over the Indian subcontinent.

Modelling studies directed at understanding the relationship between tropical forests and rainfall with realistic models of the biosphere have simulated a warmer and drier climate in response to Amazonian deforestation. Since forests absorb more solar energy and produce much larger evaportranspiration, as well as moisture convergence through the surface-roughness effect, positive feedback effect of forests on precipitation can be expected naturally. Our new simulation experiments not only reaffirmed the above results but also suggested potential global consequences due to the ongoing deforestation. From a synthesis of modeling results of the last decade, it if further inferred that variations in the biosphere-atmospheric interactions play an important role in redistributing continental precipitation to fulfill the survival and growth requirements of different biomes: forests, pasture, agricultural lands, and deserts.
A study of wind chill effect at Maitri, Antarctica
Authors: KULANDAIVELU E. , SINGH SARBJIT
Published: January 2022

The influence of meteorological parameters like wind and temperature determine the chillness upon the human body. The rate of heat removal from the human body by wind and low temperature was termed as Wind Chill by Siple and Passel (1945). Using the wind chill chart wind chill effects at Maitri, Antarctica during 1990 have been studied and compared with conventional value of monthly mean dry bulb and minimum temperatures. It has been observed that the wind chili temperature was about 15°-25°C lower than the dry bulb temperature when the wind speed exceeds 10 kt.
Skills in prediction of 5-day monsoon rainfall by using self-analogues
Authors: KULKARNI ASHWINI , SINGH S. V.
Published: January 2022

Potential of rainfall self analogues in forecasting 5-day monsoon rainfall over India is examined 5-day rainfall maps during July-August of 80 years (1901-1980) (total 960%) are searched for the analogues by an objective computerized procedure. Low but positive skills with higher values over western parts of the country have been obtained. Use of group of analogues is found to improve the skills though only marginally.

The self analogue technique has been applied for 1987 (drought year) and 1988 (good monsoon year) to assess its predictive value.
Depth area duration analysis of short duration rainfalls
Authors: KOTHYARI U. C. , GARG S. K.
Published: January 2022

Depth Area Duration (DAD) analysis for the extreme rainfall events forms an important step in the hydrological design for the water resources structures. Review of literature reveals that enormous amount of work has been done concerning the DAD analysis for large duration (i.e. one day or more) storms. However, no work is reported so far on this aspect for storms having shorter duration. i.e. less than one day:

Hourly rainfall data for 36 rainfall stations have been analysed  to develop simple DAD-relationship. This analysis pertains to the catchments of the rivers, namely Ramganga, Gomati, Yamuna  and Ghaghara.
Variability and probabilistic estimates of rainfall extremes In Bangladesh during the southwest monsoon season
Authors: KARMAKAR SAMARENDRA , KHATUN AYESHA
Published: January 2022

The present study describes the temporal and spatial distributions of mean monthly rainfall and its variability together with the spatial distributions of the probabilistic estimates of rainfall extremes over Bangladesh during the- southwest monsoon season. The- probabilistic rainfall extremes have been computed for IWO lime scales: (a) in I year out of 4 years, and (b) in 1 year out of 10 years -representing relatively less extreme events and extreme events respectively. The mean monthly rainfall increases from June to July at most places over Bangladesh and then decreases up to September. The variability of rainfall decreases with increasing rainfall up to July at many places and then increases up to September. The study also reveals that the mean rainfall and the- probabilistic rainfall extremes are maximum over the southern and north-eastern parts of the country where the variability of rainfall is low and the rainfall is reliable. There exists a belt of low rainfall over the- central part of Bangladesh roughly between 23oN and 24°N. The rainfall gradients are maximum over north-eastern Bangladesh and the gradients of the probabilistic high rainfall are more than those of the probabilistic low rainfall in this area.
Spectral radiance characteristics and vegetative indices of crops -A ground based remote sensing technique
Authors: DUBEY R. C. , GAIKWAD S. D. , NAWATHE V. S. , DEKHANE R. G. , BIDYANTA S. N.
Published: January 2022

The spectral radiance characteristics and vegetation indices like simple difference, ratio vegetation, normalised vegetation perpendicular vegetation transformed vegetation and tasseled cap transformation of mung been sunflower and groundnut crops at different growth stages have been studied. The experiment was conducted in post rainy season during 1990-91 in the farm of Agricultural College. Pune using hand held multi-spectral radiometer. The significance of spectral variation of radiance and vegetative indices with respect to the phenological stages are discussed.
Estimation of potential evapotranspiration using a single weather element -The evaporation
Authors: BHANDARI S.C. , SHAHA S. K.
Published: January 2022

Knowledge of potential evapotranspiration is a basic requirement in any study related to crop water management Observing the conceptual similarity between potential evapotranspiration and evaporation an attempt has been made to establish a linear relationship between the two.

Using 10 years potential evapotranspiration and evaporation data, linear regression analysis was carried out. Three stations, namely, Bangalore, Pune and Hissar in different latitude belts were selected for the present study. It was observed that partitioning of the annual period into dry and wet periods gives better results. Analysis of l0 years data for dry as well as wet period shows that correlation coefficient is more than 0.95 and variance of residual is very small for each data set.

 

Using the linear regression equation, potential evapotranspiration values were predicted for independent data set. It was found that correlation coefficient between estimated and observed potential evapotranspiration exceeds 0.90, implying that more than 80% of the variation in potential evapotranspiration can be explained by this simple method. Error analysis and also Chi-square test show that predicted values are quite close to observed values.
A prominent maximum in surface ozone concentration during winter months at Pune (India)
Authors: TIWARI V. S. , PESHIN S.
Published: January 2022

ABSTRACT. Concentration of ozone near the ground has been recorded at Pune (India) since 1972 with the help of a continuous surface ozone recorder using electro-chemical sensor. The analysis of the records of winter season indicates a sharp rise in ozone amount in the forenoon around 1000 to 1200 LST. Prior to 1985  this forenoon: higher value in surface ozone concentration was followed by another maximum in the afternoon hours coinciding with the maximum temperature epoch of the day. After 1985 the surface ozone data  indicates that the forenoon peak value has become invariably higher than the afternoon value. Due to increasing concentration of anthropogenic gases in the atmosphere there is a possibility of photochemical production of ozone in the troposphere which may give rise to higher  surface ozone values,  when the meteorological conditions are favourable for the accumulation of such gases which are involved in ozone production.
1 to 10 days extreme rainfall studies for Kerala state
Authors: SASEENDRAN S. A. , SINGH K. K. , BAHADUR J. , DHAR O. N.
Published: January 2022

The daily rainfall data for 80 years from 98 stations in Kerala region have been analysed to arrive at the Probable Maximum Precipitation (PMP) estimates for rainfall durations or 1 to 10 days. Hershfield's statistical technique has been adopted for the estimation of PMP from annual maximum data. The study will be useful in the estimation of extreme precipitation for computation of design floods, required for design of spillways of dams and other major hydraulic structures in the Kerala state.
A study on the consumptive use of water by kharif rice at Canning (West Bengal)
Authors: DAS H.P. , CHOWDHURY A. , GAONKAR S. B.
Published: January 2022

Based on the data for the period from 1977 to 1992 during the kharif season. mean weekly evapotranspiration (ET) and its contribution for different phases to total evaporative loss have been worked out for kharif rice at Canning. The evapotranspiration-evaporation ratio (ET/EP) and crop coefficient (Kc) have been round to attain peak values during the flowering stage. A relationship between ET/EP and number of days from transplanting has been developed and this relationship helps in detero\ining ET from a knowledge of EP and date of transplanting. Ratio of evapotranspiration to total shortwave radiation (ET/R2) which represents the combined effect of energy balance components. also reaches its peak value during the flowering stage. Among the four different energy summation indices. the potential evapotranspiration seems to be a better parameter for identification of growth stages of the crop. Water use efficiency of kharif rice shows significant year-to-year variations.
The relationship between geopotential height and movement & landfall of tropical cyclone in the Bay of Bengal region
Authors: DAS G.K. , MIDYA S.K. , DEBNATH G.C. , ROY S.N.
Published: January 2022

In this paper a simple relationship is employed to investigate relative impacts on the movement and landfall of tropical cyclone in the Bay of Bengal region when geopotential height of different troposphere levels is used as an input. Five tropical cyclone during pre-monsoon and post-monsoon season over the Bay of Bengal region has been selected for the study. The RS/RW data of coastal stations namely Kolkata (Dumdum), Dhaka, Agartala, Bhubaneswar, Visakhapatnam, Machlipatnam, Chennai and Karaikal has been collected for the period of the cyclones under study. The geopotential height of different standard levels has been plotted against the time for the stations for every cyclone. The study suggests that the cyclone moves towards and cross near the station having relatively steeper decrease in geopotential height upto mid tropical level followed by increased in geopotential height.
Development of 1961-1990 monthly surface climatology of India and patterns of differences of some meteorological parameters with respect to the 1951-1980 climatology
Authors: JASWAL A.K. , BHAMBAK S.R. , GUJAR M.K. , MOHITE S.H. , ANANTHARAMAN S. , BHAGYALAKSHMY S.
Published: January 2022

Climate normals are used to describe the average climatic conditions of a particular place and are computed by National Meteorological Services of all countries. The World Meteorological Organization (WMO) recommends that all countries prepare climate normals for the 30-year periods ending in 1930, 1960, 1990 and so on, for which the WMO World Climate Normals are published. Recently, Climatological Normals for the period 1961-1990 have been prepared by India Meteorological Department (IMD) which will change the baseline of comparison from 1951-1980. In this paper, preparation of the 30-year Climatological Normals of India for the period 1961 to 1990 and spatial patterns of differences of annual means of temperatures, relative humidity, clouds, rainfall and wind speed from the previous normals (1951-1980) are documented.The changes from earlier climatological normals indicate increase in annual means of maximum temperature, relative humidity and decrease in annual means of minimum temperature, cloud amount, rainfall, rainy days and wind speed over large parts of the country during 1961-1990. The spatial patterns of changes in dry bulb temperatures and relative humidity are complementary over most parts of the country. Compared with 1951-1980 climatology, there are large scale decreases in annual mean rainfall, rainy days and wind speed over most parts of the country during 1961-1990. The decrease in wind speed may be partly due to changes in exposure conditions of observatories due to urbanization.
Analysis of Ocean-Atmospheric features associated with extreme temperature variation over east coast of India-A special emphasis to Orissa heat waves of 1998 and 2005
Authors: JENAMANI RAJENDRAKUMAR
Published: January 2022

During the decade of 1998-2007, both Orissa and Andhra Pradesh at east Coast of India have been affected by heat waves more frequently and more severely causing very high damages to human lives. The most severe heat wave years for the region in the recent past are summer of 1998 over Orissa and 2003 over Andhra Pradesh when 2,042 and nearly 3054 people lost their lives respectively. In summer of 2005, though severe heat wave conditions were experienced for some days over Orissa and adjoining east coasts, the damages were not high as before. In view of such extreme temperature events have been regularly affected the region during the period where their normal frequency is low, analyses of their long period temperature data and study of their relationship with various regional and global ocean-atmospheric features are very much necessary, to find possible causes and then use them in forecasting. In the present study, an attempt has been made to analyze various temperature time series as available, varying from large domain to small domain, e.g., all India temperature, east coast of India temperature etc., to understand whether years which had recorded extreme temperatures in these larger domains have any relationship with that occurred over its very smaller domain, e.g., Orissa from station data, of which later is a part. To understand the relation between the magnitude of heat indices and loss to total human lives it caused during respective whole periods of heat waves, different heat indices, viz., general heat indices, Thom’s discomfort and Webb’s comfort indices have been computed during these extreme years over Orissa and Andhra Pradesh states and compared with total heat wave related human deaths over the respective states for the corresponding years. In addition to various heat indices, various Ocean-atmospheric characteristics, e.g., monthly SST over Bay of Bengal, day-to-day synoptic flow pattern, recurving Cyclonic Storms which strengthen low-level westerly and prohibit onset of Sea breeze over the coastal stations in the region causing persistent of heat waves, have also been critically analyzed both spatially and temporally to find role of these features in such occurrences. Their statistical lag correlations if any with ensuing temperature rise have been tested to explore the possibility of using them in forecasting these events much in advance.
Rain drop size distribution characteristics of cyclonic and north east monsoon thunderstorm precipitating clouds observed over Kadapa (14.47°N, 78.82°E), Tropical semi-arid region of India
Authors: KUMAR S.BALAJI , REDDY K.KRISHNA
Published: January 2022

Hkkjr ds vkU/kz izns’k jkT; ds v/kZ'kq"d HkwHkkx] dM+ik ¼14-47 fMxzh m-] 78-82 fMxzh iw- ½ esa yxk, x, d.k ds vkdkj vkSj osx ¼ikjohosy½ okys fMLMªksehVj l ‘ty’ pØokr ls mRiUu o"kZ.k es?kksa ¼07 uoEcj 2010½ rFkk mRrj iwoZ ¼,u- bZ-½ ekulwu xtZ okys rwQku ds o"kZ.k es?kksa ¼16 uoEcj 2010½ ds cw¡n ds vkdkj ds forj.kksa ¼vkj- ,l- Mh-½ dks ekik x;k gSA izs{k.kkRed ifj.kkeksa ls gesa ;g irk pyk gS fd pØokr dh otg ls mRiUu o"kZ.k es?kksa esa laoguh o"kZ.k izcy jgkA tcfd mRrj iwoZ ekulwu ds ekeys esa xtZ okys rwQku o"kZ.k laoguh es?k ds Hkkx Lrjh es?kksa dh rwyuk esa vf/kd gSaA pØokr ls mRiUu o"kZ.k] mRrj iwoZ  ekulwu o"kZ.k dh rqyuk esa Lrjh {ks= ¼laoguh {ks=½ esa NksVh cw¡nksa ¼NksVh vkSj e/;e vkdkj dh cw¡nksa½ ls laca/k gSA Lrjh vkSj laoguh es?k {ks=ksa esa mRrj iwoZ ekulwu o"kZ.k dh rwyuk esa vkSlr nzO;eku Hkkfjr O;kl] pØokr ls mRiUu o"kZ.k dk Dm de gSA o"kkZ dh cw¡nksa ds vkdkj dk izs{k.k pØokrh; vkSj mRrj iwoZ ekulwu xtZ ds lkFk rwQkuksa ds o"kZ.k es?kksa esa vyx rjg dh fHkUurk ns[kh xbZ gSA

Raindrop size distributions (RSD) of  “JAL”  Cyclone induced precipitating clouds (7 Nov. 2010)  and North- East (NE) monsoon thunderstorm precipitating clouds (16 November 2010) were measured with a Particle Size and Velocity (PARSIVEL) disdrometer deployed at Kadapa (14.47°N; 78.82°E), a semiarid continental site in Andhra Pradesh state, India. From the observational results we find that stratiform precipitation is predominant than convective precipitation in cyclone induced precipitation clouds.  Where as in the case of NE monsoon thunderstorm precipitation convective cloud fraction is more than stratiform clouds. The cyclone induced precipitation is associated with  higher concentration of small drops (small and middrops) in stratiform region (convective region) than NE monsoon precipitation.  The average mass weighted diameter, Dm of cyclone induced precipitation is less than the NE monsoon precipitation both in stratiform and convective cloud regions.  The observed RSD are found distinctly vary from cyclonic and NE monsoon thunderstorm precipitating clouds.
Barotropic energetics analysis of tropical cyclone Khai Muk
Authors: BALACHANDRAN S.
Published: January 2022

bl 'kks/k i= esa 11&14 uoEcj 2008 ds nkSjku caxky dh [kkM+h esa cuus vkSj mlds vkxs c<+us okys m".kdfVca/kh; pØokr dSeqd  dh xfrdh; fLFkfr;ksa ds fo’kys"k.k ij fopkj&foe’kZ fd;k x;k tks fupys Lrj ij ifjofrZr ok;qnkc&m".kdfVca/k ¼csjksVªkfid½ mtkZ ij dsfUnzr FkkA bl nkSjku ;g ik;k x;k  fd if’peh iz’kkar egklkxj ls miks".kh; iwohZ gok;sa e/; caxky dh [kkM+h ds mRrj rd c<+h vkSj Åij m)`r vof/k esa Hkwe/;js[kh; if’peh gok;sa ¼iNok¡½ vkbZ-Vh-lh-tsM+- ds nf{k.k rd c<+h ftlds dkj.k {kSfrt; vi:i.k izokg vR;kf/kd ek=k esa cukA blls pØokrh vi:i.k Hkzfeyrk mRiUu gqbZ vkSj fo{kksHk cuk] tks ckn esa m".kdfVca/kh; pØokr dSeqd esa fodflr gks x;kA fupys {kksHkeaM+y esa ewyHkwr {ks=h; izokg ok;qnkcm".kdfVca/k :i ls vfLFkj Fkk ftls fujis{k Hkzfeyrk ds ;kE;ksrjh forj.k ds y{k.k ds ifjorZu }kjk crk;k x;k gS ftlls coaMj ds cuus esa xfrdh; ÅtkZ feyhA bl nkSjku fujis{k Hkzfeyrk ds ek/; {ks=h; izokg vkSj ;kE;ksrjh izo.krk ds chp ldkjkRed lglaca/k Fkk ftlls ok;qnkcm".kdfVca/k }kjk coaMj ek/; izokg dh vUrjfØ;kvksa ds }kjk coaM+j dh xfrdh; ÅtkZ esa o`f) gqbZA ÅtZLoh fo’ys"k.k ls irk pyk gS fd coaM+j okyh xfrdh; ÅtkZ ds ldkjkRed ifjorZu ds mPp nj ds {ks= ifjorhZ ok;qnkc m".kdfVca/k ds ldkjkRed {ks=ksa ls esy [kkrs gSa vkSj ifjorhZ m".kdfVca/k ds ifjek.k Hkzfey mRifRr okys {ks= ds vkl&ikl coaM+j okyh xfrdh; ÅtkZ ds ifjorZu ds LFkkuh; le; ds lkFk esy [kkrs gaSA ewyHkwr {ks=h; izokg ds ;kE;ksrjh vi:i.k }kjk ifjofrZr ok;qnkc m".kdfVca/k ÅtkZ m".kdfVca/kh; pØokr dSeqd ds cuus vkSj mlds vkxs c<+us okys ,d egRoiw.kZ ÅtkZ L=ksr FkkA

Analysis of dynamical conditions in respect of formation and growth of tropical cyclone Khai Muk over the Bay of Bengal during 11-14 November 2008 is discussed with focus on barotropic energy conversion at lower level. It is observed that the extension of subtropical easterlies from the Western Pacific in to central Bay of Bengal to the north and equatorial westerlies to the south of ITCZ during the above period constituted a large scale horizontal shear flow. This led to generation of cyclonic shear vorticity and initiation of disturbance which later developed in to tropical cyclone Khai Muk. The basic zonal flow in the lower troposphere was barotropically unstable as depicted by change of sign of meridional distribution of absolute vorticity which provided the kinetic energy for the growth of eddy. There existed positive correlation between mean zonal flow and the meridional gradient of absolute vorticity which favoured increase of eddy kinetic energy through barotropic eddy-mean flow interactions. Energetic analysis indicated that areas of high rate of positive change of eddy kinetic energy coincided with positive areas of barotropic conversion and the magnitude of barotropic conversion matched with local rate of change of eddy kinetic energy around the area of vortex generation. Barotropic energy conversion by meridional shear of basic zonal flow was an important energy source for the formation and initial growth of tropical cyclone Khai Muk.
Track, intensity and few dynamical aspects of ‘AILA’ as simulated by operational NWP model of the IAF
Authors: SRIVASTAVA T.P. , DEVRANI ANIL
Published: January 2022

bl 'kks/k i= esa Hkkjrh; ok;q lsuk ds izpkyukRed ,u- MCY;w- ih- ekWMy dh {kerk dk ebZ 2009 esa caxky dh [kkM+h esa cus vkSj if’pe caxky dks izHkkfor djus okys izpaM pØokrh; rwQku ^vk;yk^ ds dqN xR;kRed igyqvksa] mlds ekxZ] rhozrk ,oa LFky izos’k ds iwokZuqeku dk fo’ys"k.k djus dk iz;kl fd;k x;k gSA bl ekWMy dks 6 fd- eh- ds NksVs Hkkx esa diklh izkpyhdj.k ;kstuk ds lkFk vkSj mlds fcuk bl ;kstuk dk iz;ksx djds ns[kk x;k gSA ckjh ckjh ls fd, x, nksuksa iz;ksxksa ds lsV esa Mh&2 ij rS;kj fd, x, iwokZuqeku dh rqyuk esa Mh&1 ds iwokZuqeku vis{kk—r csgrj vkSj vkf/kd lgh ik, x,A diklh izkpyhdj.k ds iSVUlZ foyac ls laogu iSnk djrs gSa ijUrq bl iSVUlZ ds fcuk rS;kj fd, ifj.kke dh rqyuk esa vf/kd lgh gSA 6 fd-eh- ds NksVs Hkkx esa diklh izkpyhdj.k ;kstuk ds fcuk jsMkj dh ijkofrZrk Mh- MCY;w- vkj- dksydkrk ds okLrfod ijkofrZrk le; vkSj LFkku nksuksa dh rqyuk esa vf/kdre ns[kh xbZ gSA

An attempt has been made in this study to analyse the efficacy of operational NWP Model of the IAF in predicting the track, intensity, landfall and few dynamical aspects of ‘AILA’ a Severe Cyclonic Storm that formed over the Bay of Bengal and affected West Bengal during May 2009. Model runs were done with and without employment of cumulus parameterisation scheme in the finer domain of 6 km. The forecasts of D-1 were relatively better and more realistic in comparison to the one generated on D-2, in both sets of experiment, respectively. Patterns with cumulus parameterisation produced delayed convection but with finer details in comparison to the patterns generated without it. Maximum radar reflectivity without using cumulus parameterisation scheme in the finer domain of 6 km, compared well with the actual reflectivity of Kolkata DWR both in time and space.
A case study for cyclone ‘Aila’ for forecasting rainfall using satellite derived rain rate data
Authors: BISWAS HABIBURRAHAMAN , KUNDU P.K. , PRADHAN D.
Published: January 2022

caxky dh [kkM+h esa cuus ,oa tehu ls Vdjkus okys pØokrh; rwQkuksa ds  ifj.kkeLo:i  Hkkjh o"kkZ dh otg ls if’pe caxky ds rV lesr Hkkjr ds iwohZ rV ds yksxksa dh tku eky dks dkQh [krjk jgrk gSA tehu ls Vdjkus okys m".kdfVca/kh; pØokrh rwQkuksa dh otg ls gksus okyh o"kkZ dh ek=k dk iwokZuqeku djuk cgqr dfBu gSA m".kdfVca/kh; pØokrh; rwQkuksa ds nk;js esa vkus okys o"kkZ okys {ks=ksa esa laHkkfor pØokrh; rwQku ls gksus okys o"kkZ lap;u dk iwokZuqeku djus ds fy, mixzg ls izkIr o"kkZ njksa dk mi;ksx fd;k tk ldrk gSA bl 'kks/k i= esa ‘vkbyk’ ds m".kdfVca/kh; o"kkZ ekiu fe’ku ¼Vh- vkj- ,e- ,e-½] mixzg o"kkZ nj vk¡dM+ksa rFkk rwQku ds ns[ks x, ekxZ dk mi;ksx djrs gq, m".kdfVca/kh; pØokr ‘vkbyk’ ds tehu ls Vdjkus ls 24 ?kVsa igys rVh; LVs’kuksa ij o"kkZ dk vkdyu djus dk iz;kl fd;k x;k gSA la;qDr jkT; vesfjdk esa fodflr lqifjfpr rduhd ds vk/kkj ij  m".kdfVca/kh; pØokr ‘vkbyk’ ds tehu ls Vdjkus ds 24 ?kaVs igys m".kdfVca/kh; o"kkZ foHko ¼Vh- vkj- ,- ih-½ iwokZuqeku fo’ks"k :i  ls rwQku dh fn’kk ds lkeus vkus okys rVh; {ks=ksa ds fy, vPNh o"kkZ dk iwokZuqeku miyC/k djkrk gSA

Major threat to the life and property of people on the east coast of India, including West Bengal Coast, is due to very heavy rainfall from landfalling tropical cyclones originated over Bay of Bengal. Forecasting magnitude of rainfall from landfalling tropical cyclones is very difficult. Satellite derived rain rates over the raining areas of tropical cyclones can be used to forecast potential tropical cyclone rainfall accumulations. In the present study, an attempt has been made to estimate 24 hours rainfall over coastal stations before landfall of tropical Cyclone ‘Aila’ using Tropical Rainfall Measuring Mission (TRMM) satellite rain rates data and observed storm track of Aila. Forecast Tropical Rainfall Potential (TRaP), 24 hours prior to landfall for the tropical cyclone ‘Aila’ based on well known technique developed in USA, provides a good rainfall forecast especially for the coastal areas lying at the head of direction of the storm.