J&K Snow Data-1

8/6/2019 J&K Snow Data-1

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Defence Science Journal, Vol 49, No 5, October 1999, pp. 437-4450 1999, DESIDOC

Snowfall Statistics of Some SASE Field Stations in J&KA.P.Dimri

Snow & Avalanche Study Establishment, Manali- 175 103.and

U.C. MohantyIndian Institute of Technology, New Delhi- 110 0 16.

ABSTRACTNorth-west Himalayan region comprises five mountain ranges. Their orientation and complexterrain influence the weather over the region. Sudden altitudinal changes also affect the weathersystems to a considerable extent . Due to the prevailing inhomogeneous topography, various dynamicand thermal processes take place at mesoscale level. In synop tic scale, during winter seasons, weathersystems, named, western disturbance (WD), take their southerly track and travel over J&K, HP an dhills of western UP, and yield considerable amount of precipitation. On the basis of past historicaldata collected over J&K region, the pattern of snowfall and its frequency distribution was studiedusing statistical means. Variation of these snowfall spells was also studied to understand spatial andtemporal changes in their distribution. A brief case study of a W D has been carried out to estimate

moisture flux inflow over Himalayas.1. INTRODUCTION

The western Himalayan rang es cover most partsof J&K, HP and the hills of western U P over northIndia. These ranges have high elevation s and runfrom north-west to sou th-east and exert considerableinfluence on the weather and clim ate of north India1Due to the complexity of terrain and in accessibilityto several areas ifi the Himalayan region, knowledgeof climate, characteristics of snowfall and btherhydrometeors, their frequency of occurrence , intensityand duration, and also their variation in tim e andspace is limited. Snowfall occurs over westernHimalayas mainly during November to April inassociation with eastward-moving low pressure system s,known as western disturbances (WDs). Thesedisturbances are often observed a s closed low s onthe m ean sea level w eather ch arts. or as troughsRevised 23 August 1999

in the upper levels over the Indo-Pakistan region,and generally m ove ENEwards across north India,causing w idespread precipitation o ver north India.Generally,6-7 such disturbances m ove across westernHimalayas in a month during the winter months.Of these, 1-2 remain of severe intensity, causingextensive cloudiness, heavy precipitation, strongwinds, sev ere cold conditions and at times blizzards.Ahead of these disturbances, there is general warmingof the lower troposphere followed by cold to verycold w ind in th e rear. To understand the variabilityof winter precipitation, past historical data at afew places in J&K was considered for this study.2. DATA & ANALYSIS PROCEDURES

Th is study presents a preliminary analysis ofdaily snowfalldata recorded at four Snow& ~ v a l & c h e


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Figure1. Location of SASEfield observatories taken for studyStudy Establishment (SASE) stations in north-west J&K, viz., Haddan (long: 74"02'42", lat: 34O18'43" and alt: 3 0 8 0 m), Gulmarg (long: 74"23'0OW,lat: 34003'42" and alt: 2 8 0 0 m), Kanzalwan (long:74" 42'06", lat: 34" 38'39" and alt: 2 4 4 0 m) andSonamarg (long: 75 " 17'57", lat: 34" 18'1 1" and alt:2745 m), from November to April covering a periodof 10 years from 1985-1994. Twenty four hourcumulative precipitation was used for making snowfallclimatology for the J&K region. These four stations,shown in Fig. 1, are located at the high mountainousregions of western Himalayas with their altitudesvarying from about 2 5 0 0 - 3 1 0 0 m and lie within arange 50-100 km from each other.3. OCCURRENCE OF SNOWFALL SPELLS

OF DIFFERENT DURATIONS & THEIRVARIATIONSSnowfall spells were divided into seven categories

in terms of duration (in days) of snowfall occurrenceat a station. These were spells of durations 1 day,2 days, 3 days, 4 days, 5 days, 6-10 days and morethan 10 days. The last two categories were chosenconsidering the fact that the frequency of snowfallspells of durations exceeding 5 days is not large.Data on monthly distribution of snowfall spellsof different durations (in days) at Haddan, Gulmarg,Kanzalwan and Sonamarg are given in Table I . At

these stations, the frequencies of snowfall spellsof lday duration vary from 4 0 - 5 2 per cent andthese decrease as the duration of the spell increases.The frequencies of occurrence of snowfall spellsof more than 3 days' durationi however, are found

Table 1. Monthly distrib ution of average num ber of snowfallspells of different durations (in da ys) based on 10year (1985-94)data

(a) Had dan (long: 74W2'42", lat: 34"18'43"and alt: 3080 m)Month

1November 6December 14January 18February 16March 25April 15

Spell duration (days) i-2 3 4 5 6-10 >I07 0 3 0 0 08 4 2 1 2 0

18 6 7 0 2 07 1 0 0 3 3 1

13 10 3 1 2 18 8 4 1 0 0

(b) Gulmarg (long: 74"23'0OW,at: 3493'42" and alt: 2800 m)Month So ell duration (davs)

NovemberDecember--JanuaryFebruaryMarchApril

(c)Kanzalwan (long: 7.4"42'06", lat: 34038'39" and alt:2440 m)

Month

NovemberDecemberJanuaryFebruaryMarchApril

Spell duration (days)1 2 3 4 5 6-105 2 3 2 0 0

15 6 2 3 2 014 11 2 7 1 210 7 7 1 2 321 12 7 1 2 38 9 4 1 1 0

(d)Sonamarg ( long: 7S017'57", lat: 34"18'11" and alt:2745 m)

Month

November~ e c e m b e rJanuaryFebruaryMarchApril

Spell duration (days)1 2 3 4 57 0 0 2 0

19 2 1 2 217 13 2 2 216 14 3 0 422 16 2 5 313 5 2 0 1


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QIMRI & MOHANTY: SNOWFALL STATISTICS OF SOMESASEFIELD STATIONS IN J&K

GULMARG

NOV DEC JAN FEB MAR APRMONTHS

Figure 2. Monthly percentage frequency of snowfall spells ofall categories.to be less than 10 per cent. The probability ofoccurrence of a spell exceeding 10 days is verysmall (0.01). The frequencies of all snowfall spellshaving duration 1-3 days, taken together, lie between80 per cent and 85 per cent, indicating that spellsof up to 3 days' duration are most frequent overthe western Himalayas. However, snowfall spellsof more than 3 days' duration do occur, thoughtheir frequency is low.

Frequencies of snowfall spells increase rapidlyfrom November to January at all the four stations(Fig. 2). However, these do not show any significantchange from January to February, but again increasein March, when the occurrence of snowfall spellsis the highest over the region. There is, however,a sharp decrease in the frequencies of spells fromMarch to April. About 80 per cent of the snowfallspells of various durations occur during Novemberto April.4. SNOWFALL DAYS O F DIFFERENT

INTENSITIES & THEIR VARIATIONS INTIME & SPACEThe total number of snowfall days of different

intensities occurring at a station in each monthhave been determined and their variations in timeand space studied. The intensity of a snowfall dayis defined in terms of fresh snowfall amount recordedin 24 hr. To work out the number of days havingdifferent amounts of snowfall, these are dividedinto five class intervals, viz., 0-1 2 cm, >12-24 cm,

>24-48 cm, >48-96 cm and 48-96 cm)categories of snowfall intensities are found overa station in FebruaryIMarch. In the category ofvery heavy intensity (>96 cm) of snowfall in a day,the average number of snowfall days at a stationare found to be only 0.1-0.2 occurring from Decemberto March.

Data on frequencies of days in the five classintervals of snowfall amo'unts of > 0-12 cm,>12-24 cm, >24-48 cm, >48-96 cm and >96 cm areplotted in Fig.3. On about 50 per cent occasionsin the six-month period, snowfall days are of verylight intensity (0-12cm); on about 40 per centoccasions, these are of light to moderate intensity(>12-48 cm) and on only about 10 per cent days,the snowfall was of heavy to very heavy intensity(> 48 cm). The probability of occurrence of veryheavy snowfall intensity over a station during theperiod is very small, i.e., 1 per cent or less. It canbe seen that there is an almost exponential decreasein the frequency of days as one goes towards higherranges.

Frequencies of snowfall days of all intensitiestaken together are the highest in March and thelowest in November (Fig. 4). It is noticed that theoccurrence of snowfall days increases by 2-3 time\from November to December at all the four stationsAmong the stations, Gulmarg and Sonamarg havethe maximum occurrence of snowfall days in March.Thirty per cent of the total number of snowfalldays during the six months occur in this month atthese two stations. Considering December to Marchas the winter period for the western Himalayanregion; about 80 per cent of the total snowfall daysof all intensities fall within the above four months.


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Table 2. Average monthly frequency of snowfall days in respective ranges (percentage frequency of snowfall days taken together),(a) Hadden (long: 74" 02' 42", lat: 34" 18' 43" and alt: 3080 m)

-- - -Month Intensity (cm). - -- --A

0-12 112-24 >24-48 >96November , 1.9(51.5) 0.8(21,2) 0.7i21.2) o(0)Decembqr 3.1(50.0) 1.4i23.2) l.O(l6.1) 0.22(3.6)January , 6.1(56.5) 2.4(22.2) 1.5(13.9) o(0)~ e b r u a r ) 5.9(51.8) 2.3i20.2) 2.0(17.5) 0. I O(O.9)March 6.2(30.0) 2.5(20.2) 2.7(21.8) O(0)April 4.5(59.2) 2.1(27.6) 0.7 (9.2) 0.30(3.90) O(0)

(b) Gulmarg (long: 74" 23'001', fat: 34" 03'42" and alt: 2800 m)

November 1.6(86.7) 0.13(6.7) 0.13 (6.6) o(0) O(0)December 2.5(50.0) l.O(l8.2) 0.90(15.9) 0.75(13.6) 0.1 3(2.3)January 4.5(53.2) 2.0(23.4) 1.80(20.8) ' 0.22 (2.6) o(0)February 6.1(55.6) 1.9(17.2) 2.00(18.2) 1.00 (9.1) O(0)March 5.8(47.3) 3.6(29.1) 2.10(17.3) 0.80 (6.4) o(0)April 2.3(77.8) 0.6(18.5) 0.11 (3.7) o(0) o(0)

(c) Kanzalwan (long: 74" 42'06", lat: 34" 38'39" and alt: 2440 m)Month Intensity (cm)

0-12 >12-24 >24-48 >48-96 >96November 2.3(62.0) 0.7(19.0) 0.6(15.0) 0.14 (3.8) o(0)December 4.4(56.4) 1.6(20.0) 0.6 (7.3) 1.14(14.5) 0.14(1.8)January 5.3(46.7) 2.3i20.0) 2.9(25.6) 0.90 (7.8) O(0)February 4.4(37.2) 2.5(21.3) 3.3(27.7) 1.60(13.8) O(0)March 5.0(39.2) 3.9(30.4) 2.6(20.6) 1.30 (9.8) o(0)April 4.5(76.6) 1.3(21.3) 0.12i2.1) o(0) 0)

-

(d) Sonamarg (long: 75" 17'57", lat: 34" 18'11" and alt: 2745 m)Month Intensity (cm)

0- 12 >12-24 >24-48 >48-96 >96November 1.60(61.6) 0.6(22.2) 0.42(16.7) o(0) 0 )December 3.14(39.3) 2.0625.0) 1.7 (21.4) 0.86(10.7) 0.30(3.6)January 4.10(47.1) 1.4(15.7) 2.4 (27.1) 0.90(10.0) o(0)February 4.30(39.5) 2.6(24.4) 2.1 (19.8) 1.60(15.1) 0.13(1.2)

, March 5.90(40.5) 3.6(25.0) 3.0 (20.7) 1.80(12.1) 0.30(1.7)April 2 40(54.3) 1.4(3 1.4) 0.40 (8.6) 0.30 (5.7) O(0)--A -- -.


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DIMRI & MOHANTY: SNOWFALL STATISTICSOF SOME SASE FIELD STATIONS IN J&K

601 H HADDANGULMARGEJ KANZALWAN

SONAMARGGULMARGKANZALWAN-5 400 SONAMARG

3I$ 300

5 20 0100

01 2 3 4 5 6to 10 >I0SNOW SPELLS (DAYS)

Figure 5. Highest amount of cumulative snowfall occurring inspells of different durations.0-12 >12-24 ~24-48 >48:96 >96

SNOWFALL RANGES (cm)Figure 3. Percentage frequency of snowfall days in differentamount ranges.5. HIGHEST CUMULATIVE SNOWFALL

AMOUNTS IN SPELLS OF DIFFERENTDURATIONSData on the highest snowfall amounts recordedin spells of different durations are presented inFig. 5. It is seen that generally with increase inthe duration of the snowfall spell, the amount ofsnowfall recorded at a station also increases. However,there are a few exceptions. For example, at Kanzalwan,

the highest snowfall recorded during a spell of>10 days was 249 cm, which is much less than theamount recorded at the same station during a spell'HADDANGULMARGKANZALWAN30

0 SONAMARG>250ZW$202W 150zZ6 10a:Wa 5

0NOV DEC JAN FEB MAR APR

MONTHSFigure 4. Monthly percentage frequency of all amount rangestaken together.

of 6-10 days. Similar distributions were observedat Haddan and Gulmarg, where the snowfall amountsreceived during a 4 days ' spell is less than thoseoccurring during a spell of 3 days ' duration. Thehighest amount of snowfall was 486 cm recordedat Sonamarg in a spell of >10 days during 10years.6. CASE STUDY OF A WESTERN

DISTURBANCEThe synoptic situation of a WD was examinedas a case study. A WD, as an upper air cyclonicsystem moved across north-west India during7- 10 December 1997. This was a very active disturbanceand caused rain or snow at almost all places in HP,hills of western UP and a few places in J&K.

INSAT imageries at 0600 UTC (visiblechannel) of all these days are reproduced in Fig.6.From surface features it is noticed that the twocyclonic circulations at 850 hpa, one close to /northGujarat and the other over Punjab, moved dlowlynorth-eastwards towards the hills of HP and westernUP. At 300 hpa, a north-south-oriented upper airtrough persisted at 70-75"E and north of 25"Nduring 7-9 December 1997. It moved towards northeast on 10 December 1997 and lay along 80E.The satellite pictures indicate advection of cloudsand hence the moisture from the Arabian sea intothe region of low level cyclonic circulations or totheir east and concentrating over the region ofPunjab, Harayana, HP, hills of western UP andJ&K. Presence of westerly trough at upper levelhad intensified the system, causing widespread


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DEF SCI J, VOL 49, NO 5 , OCTOBER 1999

07 December 1997: 0600 UTC 08 December 1997: 0600 UTC

09 December1997: 0600 UTCFigure 6. Visible INSAT cloud imager

10 December 1997: 0600 UTC

or storm period 07-10 December 1997


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DIMRI & MOHANTY: SNOW FALL STATISTICS OF SOM E SASE FIELD STATIONS IN J&K

54E 60E 66E 72E 78E 54E 60E 66E 72E 78E

07 DECEMBER 1997 : 0000 UTC 08 DECEMBER 1997 :UTC

54E 60E 66E 72E 78E

09 DECEMBER 1997 :0000 UTC

54E 60E 66E 72E 78E

10 DECEMBER 1997 : 0000 UTC

Figure 7. Total precipitable water content (glcc) for storm period 07-10 December 1997


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DEF SCI J , VOL 49, NO 5, OCTOBER 1999

precipitation. Th e trough was form ed due to mediumand high level clouds form ing ahead of the westerlies2.These south-wes t and north-eas t m edium an d highlevel clouds ove r the region a re baroclinic in natureand are the main c ause of l i f t ing of m ois ture f romthe Arabian sea . During th e s torm period, the skyremained overcas t wi th low and medium c l o ~ d s ~ , ~ .T h e H i m a l a y a n m o u n t a i n r a n g e s m o d i f y t h esynopt ic sca le weather sys tem approaching theIndian longitudes from the west. Su rface observationof snow -meteorologica l parameters show that WDsometimes get in tens if ied and a t t imes s low dow ntheir movement in the vic ini ty of the Himalayasand thus cause local heavy snow fal l over the hi llyareas of J&K, HP and wes tern UP.

Intensification of a W D is seen to be generallyaccompanied by incursion of warm moist air frombay of bengal or the Arabian sea in to low pressureinduced by development in the wes ter l ies . Toinvestigate the accumulation of moisture duringthe per iod of s torm that sus ta ined the WD andcaused widespread precipitation, National Centre,for Atmospheric Research (NCAR), USA, dai lyre-analysis of total precipitable water content ofthe a tmosphere a t 00 UTC dur ing 7 -10 December1997 is con sidered; the calculated values*ofmoisturecontent a re shown in Fig .7 . I t i s seen tha t thecalcula ted values are in conformity with c loudsshown in Fig. 6. Two belts of m aximum precipitablewater content (g lcc) , one extending from A rabiansea to north-wes t C hina and the other f rom southIran to Gujarat in India, persisted during 7-9 De cem ber1997. In between thes e two belts of m axim a oftotal precipitable water content, a relatively drybelt of moisture was observed running from southCaspian sea to northern Rajasthan. On 10 December1997, the northern bel t of m aximum precipi tablewater content weakened considerably and shiftednorth-eastwards and the southerly belt shifted furthersouthwards in to the Arabian sea . Widespread andheavy rainfall over J&K, HP and wes tern hi l ls ofUP was recorded du ring 7-9 Decem ber 1997. I t i sprobable that a relatively dry air belt between twovery moist belts, coupled with syn optic disturbancesand topography caused considerable instabili ty,particularly on the Himalayan ranges and hence

widespread and heavy p rec ip i t a t ion . From 10Decem ber 1997, when the two mois t and dry bel tsbecame less marked, the p recipitation belt decreasedand moved eas twards .7. CONCLUSIONS

From statis t ical trends of WD of the past 10years , i t is seen that weathe r associated with a W Dlasts for 2-4 days, but the disturbed weather conditionspersis t for 5 days o r even more . Such a s ituationnormal ly occurs when WDs approach north-wes tIndia one af ter the other in quick success ion a tintervals of 1 -2 days. Also , slow moving or stationarydisturbances may c ause adv erse weather conditionsfor much longer dura t ion over the hi l ly regions .

I t may be concluded from the case s tudy tha ta s low moving WD coupled with a wel l -markedupper level t rough a t 300 hpa and above movedinto the hil ls from southern Rajasthan, Punjab1Haryana regions. Two belts of very high totalprecipitable water content with a relatively drybelt with much less precipitable water content inbetween were observed.ACKNOWLEDGEMENT

Shri Dimri expresses his thanks to Maj GenS . S . S h a r m a , K C , V S M , D i r e c t o r, S A S E , f o r h iscont inuous encouragement and guidance .REFERENCES1. Williams, P. (Jr) & Peck , E.L. Terrain influenceon precipitation in the intermountain west asrelated to synoptic s ituation. J. Appl.Meteorol. ,September 1962, 2, 343-47 .2. Kalsi, S.R . & Halder, S.R . Satellite observationsof interaction betw een tropics and m id-latitudes.Mausam, 1992, 43 ( I ) , 5 9 - 64 .,3. A'gnihotri, C.L. & Singh, M.S. Satell i te s tudyof wes tern dis turbances . Mausam , 1 98 2,3 3 (2),249-54.4. Bhaskar Rao, N.S. & Moray, P. E. Cloud systemsassociated with western disturban ce: A preliminarystudy. Indian J. Meteorol . Geophys . , l97 1 , 22,413-20 .


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DIMRI & MOHANTY: SNO WFALL STATISTICS OF SOME SAS E FIELD STATIONS IN J& K

Mr AP -Dimri dbta ined his MSc (Tech) in Geophysics (Meteorology) f rom the Banaras HinduUnivers i ty , Varanasi , in 1992. In 1994, he compele ted his M PN l in ~n vi ron me nt a l c iences f romJawaharlal Nehru University, New Delhi. In the sam e year , he joined DR DO at the Snow &Avalanche Study Estt , Manali . Presently, he is involved in weather forecasting at some of thes ta t ions in J&K and H P using s ta t i s tica l and dynamica l methods .

/'

Prof UC Mohanty obtained his PhD (Tropical Meteorology) from USSR in 1978. Presently, heis working as Professor and Head of the Centre for Atmospheric Sciences at the Indian Insti tuteof Technology (IIT) , New Delhi. He is having more then 26 years of research and teachingexperience in atmospheric sciences. He has been honoured with several awards, including Shantiswaroo p Bhatnagar Award, (1993). He has published more than 70 papers in internationallnationaljourna ls. H e is a member of many professional societies related to atmospheric sciences. His fieldsareas of specialisation are: tropical meteorology, numerical weather prediction, monsoon dynamicsand c l imate model l ing.

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J&K Snow Data-1