An appraisal of precipitation distribution around the Everest and Kanchenjunga peaks in the Himalayas

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1 Weather Vol. 55 July 2000 An appraisal of precipitation distribution around the Everest and Kanchenjunga peaks in the Himalayas 0. N. Dhar and Shobha Nandargi Indian Institute of Tropical Meteorology, Pune, India The Himalayan range has been described as the greatest physical feature on earth. Because of its enormous size and altitude it is also called the 'third Pole'. It runs from Mount Namche Barua (7756m) in the east to Mount Nanga Parbat (8126m) in the west for a distance of about 2400km in the form of an arc with convexity towards the south. In the northwest, the Himalayan foothills start from about 34 ON and in the east this lofty mountain range runs down to about 28"N (see Fig. 1). The Himalayan range consists of three broad ranges parallel to each other: (i) The Siwalik, or outer Himalayan range. (ii) The Lesser Himalayas, or middle range. (iii) The Great Himalayan, or innermost range. The three ranges are separated from one another by longitudinal fertile valleys. The entire Himalayan range is the source of 22 major rivers of the Indian subcontinent; these derive their water from numerous glaciers and ice caps which have accumulated on the slopes of the Great Himalayan range and its subranges over thousands of years (see Fig. 1). The Great Himalayan range is the boundary between the Indian subcontinent and the Fig. 1 The Great Himalayan range and catchments ofhimalayan rivers (from Dhir and Singh 1956) 223

Weather Vol. 55 July 2000 Nuptse Mt. Everest Lhotse (7885 m) (8848 m) (8506 m) Fig. 2 Summit of Everest as seen fiom Tengboche (3857m), eastern Nepal plateau of Tibet to the north.

2 Weather Vol. 55 July 2000 Nuptse Mt. Everest Lhotse (7885 m) (8848 m) (8506 m) Fig. 2 Summit of Everest as seen fiom Tengboche (3857m), eastern Nepal plateau of Tibet to the north. Besides this, it also serves as a climatic divide between the tropical Indian subcontinent and semi-arid Tibet, which is located at an altitude of 4 to 5 km. The entire Great Himalayan range is dotted with 29 high peaks whose elevations vary from 7756m (Mount Kamet) to 8848m (Mount Everest). In this study an attempt has been made to get an idea of the precipitation distribution around two lofty peaks in the eastern Himalayas: Mount Everest (27'53'N, 86" 55'E) (Fig. 2) and Mount Kanchenjunga (8598m, 27 45'N, 88 12'E) (Fig. 3). Mount Everest is the highest peak in the world and Mount Kanchenjunga is the third highest. The second highest peak, K2 (861 1 m), lies in the Karakorum range, north-west of the Himalayas. Before we actually examine the precipitation distribution around these two high peaks, it may be appropriate to mention briefly the climatology of precipitation over the Himalayas, whose geographical location is so vital to the south-east Asian region for the generation and maintenance of the south Asian monsoon. This has been shown by the numerical model studies of Godbole (1973) and Hahn and Manabe (1975). According to them, if the Himalayan mountains were removed from their present location, south-east Asia would have no season like the monsoon. Precipitation climatology of the Himalayas The climate of the Himalayas has been described by various workers in the past, notably Mani (1981) and Das (1983). In recent years Pant and Rupa Kumar (1997) have devoted a section to Himalayan climatology in their latest book, Climate of south Asia. There are two main seasons during which the Himalayas receive the bulk of their precipitation. These are (i) the summer (or southwest) monsoon season from June to October, and (ii) the winter season from November to March. During the monsoon season the precipitation is caused by the orographic lifting of the westward-moving Bay of Bengal branch of the monsoon over the high ranges of the Himalayas. The Bay branch gives copious amounts of precipitation over the eastern and central Himalayas. 224

Weather Vol. 55 July 2000 Fig. 3 North face of Kanchenjunga as seen fiom the base camp (5900 m) of the 1930 international expedition. In the foreground is Kanchenjunga glacier, eastern Nepal.

3 Weather Vol. 55 July 2000 Fig. 3 North face of Kanchenjunga as seen fiom the base camp (5900 m) of the 1930 international expedition. In the foreground is Kanchenjunga glacier, eastern Nepal. During the winter season extratropical low pressure systems, also called western disturbances, originate around the Caspian Sea and move from west to east along the Himalayas causing fairly widespread, light to moderate precipitation over the western and central Himalayas. By the time these disturbances reach the eastern Himalayas, they are practically denuded of their moisture. The bulk of precipitation in the form of snow and rain is obtained from these disturbances during the winter months of November to March. This precipitation forms the main source of water in the rivers of the western Himalayas during the lean spring and summer months of the year. The frequency of western disturbances is about 3 to 5 per month during the winter months. Thus the precipitation climatology of the Himalayas depends upon the winter and summer weather systems of Asia. These two systems are also influenced by the following large-scale atmospheric circulations during the two seasons: (i) East-west movement of the quasistationary upper-tropospheric Tibetan anticyclone during the summer monsoon months. (ii) Short-period fluctuations of the monsoon trough over the north Indian plains. (iii) (iv) Movement of low pressure areas (depressions or cyclonic storms) from the Bay of Bengal during the summer monsoon months. During the winter months, the northsouth movement of the subtropical westerly jet stream in the upper troposphere over the Himalayas. From the above it is seen that the Himalayas do receive precipitation in both winter and summer months and there can be a good deal of variability in the magnitude of precipitation received, because of the interaction of the various factors mentioned above. However, it is clear that the bulk of the precipitation in the western region of the Himalayas is mostly due to western low pressure systems in the mid-latitude westerlies. In the eastern and central Himalayas most of the precipitation is received from summer monsoon systems which originate from the Bay of Bengal. In the subsequent sections, the precipitation observed at stations in close proximity to Everest and Kanchenjunga is described. Location of the Everest and Kanchenjunga peaks in the Himalayas Mount Everest (Fig. 2) is located on the Great Himalayan range in eastern Nepal, which also 225

4 Weather Vol. 55 July 2000 Fig. 4 The precipitation network in the region of Everest and Kanchenjunga, eastern Nepal lfrom Chalise et a1 996). Numbered stations are as follows: 1201 Namche Bazar, 1202 Chaurikhark, 1217 Khumjung, 1218 Engboche, 1225 Sjiangbochg, Chepuwa, 1401 Olangchung Gola, 1402 Pangthung Doma, 1403 Lungthung, 1404 Taplethok, 1414 Nup, 1413 Khumachiti. happens to be the boundary between Nepal and Tibet. Mount Kanchenjunga (Fig. 3) rises about 20 km south of the general alignment of the Great Himalayan range. It is located on the boundary between Nepal and the Indian state of Sikkim, about 125km east-south-east of Mount Everest as the crow flies (see Fig. 4). Mount Kanchenjunga can be easily seen from the north Bengal foothills. Magnificent views of this huge mountain can be had from the hill stations of Dajeeling (2128m) and Gangtok (1756m) on a clear sunny morning, but the same is not the case with Mount Everest although it is about 250 m higher than Kanchenjunga. Everest cannot easily be seen from 226 the foothills of north Bengal because intervening lofty Himalayan ranges obstruct its view. However, a distant view of Everest can be had from the Singhalila range, which is a m ridge that separates Sikkim from Nepal and north Bengal, and runs due south from the southern face of Kanchenjunga. Assessment of precipitation around Everest by mountaineering expeditions In the past, various mountaineering expeditions to Everest have taken meteorological observations during their stay on the mountain. Muller (1959) recorded a total precipitation of

Weather Vol. 55 only 390 mm between 12 April and November 1956. Of the 390mm, 330mm was recorded during monsoon months.

5 Weather Vol. 55 only 390 mm between 12 April and November Of the 390mm, 330mm was recorded during monsoon months. During 1960/61, Himalayan scientific and mountaineering expeditions under the leadership of Sir Edmund Hillary spent eight months at an altitude of 5800m in the Mingbo Valley in the close vicinity of Everest. They recorded 130 mm of precipitation from December 1960 to May Of this amount, 70mm was recorded during the months of December to March and the remaining 60 mm during April to May. As early as 1960, the India Meteorological Department (IMD) (1960) estimated that the mean annual precipitation over the Khumbu glacier, which emanates from the southern face of Everest in Nepal, was of the order of 450mm. This more or less tallies with the observations of Muller (1959). Dhar and Narayanan (1965) found, on the basis of 14 years' precipitation data ( ), that Namche Bazar (3450 m), which is located about 25 km south-west of Everest, receives about 940 mm of precipitation annually. They also found that, as one approaches Everest from the south, precipitation decreases rapidly. During the period 1973 to 1976, Japanese scientists (see Inoue 1976; Yasunari and Inoue 1978) measured precipitation at a station called Lhajung (4420 m, 27"53'N, 86"50'E), which is quite close to the Everest massif, and found that the annual precipitation at this station was 508 to 543mm. Table 1 gives the monthly observed precipitation at this station during 1973 to 1975 as observed by the Japanese scientists. Similar precipitation observations for the Kanchenjunga region are not available. It is seen from Table 1 that the precipitation around Everest is mostly of monsoonal character as the bulk of the precipitation occurred during the four monsoon months of July 2000 June to September, and amounted to 75 to 83% of the annual total for these three years. Precipitation assessment using the recorded data from stations set up by the Nepal Meteorological Service Data source The IMD installed more than 50 rainfall stations in eastern Nepal under the Kosi Dam Project in In the early 1960s, the Nepal Meteorological Service (NMS) took this network under its direct control and augmented it by adding another 214 stations, making the total 264 for the whole of Nepal. On the basis of precipitation data from this network, the International Centre for Integrated Mountain Development (ICIMOD) (Chalise et al. 1996) prepared a comprehensive climatological and hydrological atlas of Nepal. This atlas has coloured plates that show the precipitation distribution. There are no tabulated data for individual stations, so it is not possible to get exact mean precipitation amounts for individual stations. Its utility for the present study is therefore limited. On request from the authors, the NMS supplied precipitation data for 12 stations (see Table 2 and Fig. 4) in close proximity to the two peaks. The data from these stations are not all for the same period, varying from 4 to 48 years. The available data are summarised in Table 2. Bearing in mind these shortcomings in the availability of data, the broad conclusions that one can draw from the data are given in the following section. Available precipitation data from meteorological stations in the neighbourhood of Everest and Kanchenjunga Precipitation at a place or region depends on Table 1 Precipitation (mm) at Lhajung (4420 m) during * Monsoon ppm as % of Year Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Annual annual * From Inoue (1 976), Yasunari and Inoue (1 978). 227

6 Weather Vol. 55 July 2000 Table 2 Details of precipitation data for stations in the neighbourhood of Everest and Kanchenjunga Station Location Station Data name code period Altitude (m? No.* (years) Actual years Mean Mean Monsoon of complete annual pptn monsoon pptn as %I data (mm) pptn (mm) of annual Everest region (27 53N, 86 SSE, altitude 8848 m) Tengboche 27 50'N, 1218 (3857) 86 46'E Khumjung 27 49'N, 1217 (3750) 86 43'E Syangboche 27 49'N, 1225 (3700) 86 43'E Namche 27 49'N, 1201 Bazar 86 43'E (3450) Earlier data (before 1963) Chaurikhark 27 42'N, 1202 (2619) 86 43'E Eurlier date (before 1963) Chepuwai 'N, 1317 (2590) 87 25'E (14) (24) , 1992 (8) , (34) (15) (49) (13) (39) , (8) , , , 1990 (16) 1975, , 1992 (5) , , , , 1978 (22) , (16) , (48) (13) , , (34) Kancheiyrngu region (27 4SN, 88 12E, altitude 8598~1) Khamachin: 27 44'N, , (4242) 87 59'E (6) 1953 (4) NuP: 27 43'N, , (4000) 87 52'E (7) 1953 (4) Olangchung 27 41'N, , , Gola 87 47'E , (3119) (27) , (18) Pangthung 27 41'N, , , Doma 87 49'E , 1953, (2818) Lungthung 27 33'N, 1403 (26) (20) (1780) Taplethok 87 47'E 27 29'N, 1404 (24) (24) 1948, (1383) 87 47'E (51) , 1953, (46) * Code number as given in the Climatic and hydroloeical atlas of Nepal (Chalise et al. 1996). i Chepuwa lies midway between the regions of Everest and Kanchenjunga and is to the south of the Great Himalayan range. :Stations closed in numerous rapidly changing variables within a pitation in the Himalayan range in time and system that is both free and complex. But space is subject to tremendous variation from because of its massive size, very high altitudes one place to another. Taking all this into and rugged orography, the occurrence of preci- Continued on p

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11 Weather Vol. 55 consideration, an attempt has been made to study the variation in precipitation in the neighbourhood of the two giant peaks of the Himalayas, although data are sparse and are not available from very close to these peaks. On the basis of all available precipitation data for the stations listed in Table 2 and Fig. 4, the mean annual and monsoon precipitation observed in the neighbourhood of Everest and Kanchenjunga are given in Table 2. Their approximate locations are shown in Fig. 4. Earlier observed precipitation data for Namche Bazar and Chaurikhark stations have also been given by way of comparison in Table 2. Data recorded by Japanese scientists in the vicinity of Everest during 1973 to 1975 are given in Table 1 which states that the annual precipitation at Lhajung (4420 m) is of the order of 500 to 540 mm. Taking into consideration stations at comparable heights it can be said that mean annual precipitation totals at stations in the Everest region are lower than those in the Kanchenjunga region. In an earlier study, Dhar (1977) estimated that precipitation in the Kanchenjunga region was almost twice that received in the Everest region. Table 2 does not support this, and it can broadly be said that the Kanchenjunga region receives higher precipitation than the Everest region but not twice the amount. It is also seen from Table 2 that, as we approach Everest or Kanchenjunga from the south (Fig. 2), precipitation starts to decrease. Although not based upon the latest precipitation data for some of the stations in Table 2, this study gives some idea of the precipitation received in the proximity of these two highest mountain peaks in the Himalayas. As stated earlier, only low hills separate Kanchenjunga from the north Bengal-Nepal plains. Because of this, these low hills do not afford protection to this mountain peak from the deflected Bay of Bengal branch of the monsoon. As a result, precipitation in and around Kanchenjunga is higher than that of Everest, which is protected by the high mountain ranges of the eastern Himalayas to its south. The monsoon winds lose much of their moisture on these high ranges by the time they reach the Everest massif. As the Kanchenjunga region receives higher July 2000 precipitation than the area around Everest there is more accumulation of ice and snow on its various faces. As a result of this, Kanchenjunga is the source of four large glaciers which originate from its different faces: the Kanchenjunga glacier from the north face, Yalung from the south-west face, Talung from the southeast face and Zemu from the east face. In comparison Everest is the source of only two large glaciers, one from its north face in Tibet (the Rongbuk glacier), and the other from its south face in Nepal (the Khumbu glacier). The greater number of glaciers emanating from Kanchenjunga is positive proof that the region surrounding it receives greater precipitation than Everest. Conclusions From the available meagre precipitation data around the two Himalayan giants, Everest and Kanchenjunga, it appears that the Kanchenjunga region receives greater precipitation than the Everest region. About 75 to 80% of the precipitation in both these regions is received during the summer monsoon months of June to September, indicating the monsoonal character of precipitation over these regions of the Himalayas. As one approaches these two peaks from the south, precipitation decreases rapidly because moisture is shed on the Himalayan ranges to the south. Chepuwa station (2590m), which lies midway between the two regions of Everest and Kanchenjunga, south of the Great Himalayan range (see Fig. 4), shows mean annual precipitation of 2655 mm. The name Himalayas comes from the Sanskrit, meaning the abode of snow but it is seen from the present study that precipitation is not very high over and near the Great Himalayan range, and that whatever is received, because of the high altitude of the Great Himalayan range, does not melt but accumulates year after year to form glaciers. When these glaciers advance to lower altitudes, they melt slowly and become the source of water for the rivers in the Himalayas. Epilogue Soon after the death of Mallory and Irvine on 233

12 Weather Vol. 55 Mount Everest in June 1924, Sir Francis Younghusband wrote the following: One of the great mysteries of existence is that what is most awful and most terrible does not deter man but draws him to it. Acknowledgement The authors are grateful to Dr S. R. Chalise, of the Mountain National Resources Division of ICIMOD, Katmandu, Nepal, and Dr Sunil Kansakar of the Department of Hydrology and Meteorology, Katmandu, Nepal, for readily agreeing to supply the precipitation data for stations in the neighbourhood of Everest and Kanchenjunga. Special thanks are also due to an anonymous referee and the Editor who have critically gone through the paper and offered valuable comments for its improvement. The authors also thank Dr G. B. Pant, Director, Indian Institute of Tropical Meteorology, for his constant encouragement and for giving the necessary facilities to conduct this study. References Chalise, S. R., Shrestha, M. L., Thapa, K. B., Shrestha, B. R. and Bajracharya, B. (1996) Climatic and hydrological atlas of Nepal, Katmandu. ICIMOD Das, P. K. (1983) The climate of the Himalayas. In: Singh, T. V. and Kaur, J. (Eds.) Himalayas mountains and men: Studies in the eco-development. Print House, Lucknow July 2000 Dhar, 0. N. (1977) Conquest of Kanchenjunga and weather in relation to mountaineering in the Himalayas. Vayu Mandal, J. Indian Meteorol. SOC., 3 & 4, pp Dhar, 0. N. and Narayanan, J. (1965) A study of precipitation distribution in the neighbourhood of Mt Everest. Indian J. Meteorol. Geophys., 16, pp Dhir, R. D. and Singh, H. (Eds.) (1956) Snow surveys in the Himalayas. Central Water Commission, New Delhi Godbole, R. V. (1973) Numerical simulation of the Indian summer monsoon. Indian J. Meteorol. Geophys., 24, pp Hahn, D. G. and Manabe, S. (1975) The role of mountains in the south Asian monsoon circulation. J. Atmos. Sci., 32, pp IMD (1960) Editorial. Indian J. Meteorol. Geophys., 11, pp Inoue, J. (1976) Climate of Khumbu, Himal. Seppyo, 38, pp Mani, A. (1981) The climate of the Himalayas. In: Lall, J. S. and Moddie, A. D. (Eds.) The Himalayas -Aspects of change, Oxford University Press Muller, F. (1959) Eight months of glacier and soil research in the Mt Everest region. The Mountain World, Swiss Foundation for Alpine Research, George Allen and Unwin Ltd, London Pant, G. B. and Rupa Kumar, K. (1997) Climate of south Asia. John Wiley and Sons, Chichester Yasunari, T. and Inoue, J. (1978) Characteristic of monsoonal precipitation around peaks and ridges in Shorong and Khumbu Himal. Seppyo, 40, pp Correspondence to: Dr 0. N. Dhar, Indian Institute of Tropical Meteorology, Dr Homi Bhabha Rd, Pashan, Pune , India. Back to basics: Coriolis: Part 3 - The Coriolis force on the physical earth Anders Persson Reading, Berkshire Many textbooks give the impression that the behaviour of a body on a merry-go-round tells us most of what we need to understand about the behaviour of other rotating systems, for example the earth. It is not so. The merry-go- 234 round and the earth are dynamically two quite different systems. Whereas on a merry-goround the dominating force is often the centrifugal force, c, which tries to throw out any body, this is obviously not the case on our

Who reached Mt. Everest first Missing photograph mystery?

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