Precipitation in Nepal between 1987 and 1996

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1 INTERNATIONAL JOURNAL OF CLIMATOLOGY Int. J. Climatol. 27: (27) Published online 22 March 27 in Wiley InterScience ( DOI: 1.12/joc.1492 Precipitation in Nepal between 1987 and 1996 Kimpei Ichiyanagi, a * Manabu D. Yamanaka, b Yoshitaka Muraji c and Bijaya Kumar Vaidya d a Institute of Observational Research for Global Change, Japan Agency for Marine-Earth Science and Technology, 2-1 Natsushima-cho, Yokosuka-city, Kanagawa , Japan b Graduate School of Science and Technology, Kobe University, Nada-ku, Kobe 67-81, Japan c EnergySharing Co. Ltd., Toride, Toride 32-4, Japan d Meteorological Forecasting Division, Department of Hydrology and Meteorology, Tribhuvan International Airport, Kathmandu, Nepal Abstract: Rain gauge station data from 1987 to 1996 were used to investigate spatial and temporal variability in monthly precipitation and annual and seasonal precipitation patterns over Nepal. Maximum annual precipitation increased with altitude for elevations below 2 m but decreased for elevations of 2 3 m. The data revealed a negative relationship between annual precipitation and elevation only in western Nepal. Annual precipitation averaged on a.2 grid exceeded 3 mm/yr in central Nepal but was less than 1 mm/yr over Nepal s northwestern mountains. Only winter precipitation over western Nepal was heavier than precipitation over central and eastern Nepal. A time series of standardized precipitation anomalies averaged over Nepal revealed no significant long-term trends. Further, almost no stations exhibited significant long-term trends by Kendall s rank correlation analysis. A correlation analysis between summer monsoon precipitation and the All Indian Rainfall (AIR) index revealed positive and negative correlations in western and eastern Nepal, respectively. This analysis also revealed a positive correlation, but no negative correlation, between summer monsoon precipitation and the Southern Oscillation Index (SOI) in western and eastern Nepal. Composite differences in temperature, 8-hPa winds, outgoing longwave radiation (OLR), and precipitation rates between low and high AIR phases revealed that moist air from the Arabian Sea supported precipitation over western Nepal, whereas cold dry air from the Tibetan Plateau suppressed precipitation over eastern Nepal. However, composite differences in precipitation between low and high SOI phases revealed no anomalies for Nepal. Copyright 27 Royal Meteorological Society KEY WORDS Asian summer monsoon; long-term trend; Nepal; orographic effect; precipitation Received 8 June 2; Revised 8 June 26; Accepted 4 December 26 INTRODUCTION Located between the Indian plains and the high Himalayan mountains, Nepal is characterized by steep, complex topography that makes meteorological observations difficult. Numerous studies have investigated characteristics of the Indian monsoon (e.g., Hahn and Shukla, 1976; Parthasarathy et al., 1991; Meehl, 1994; Yang and Lau, 1998; Webster et al., 1998) and its connection to El Niño/Southern Oscillation (ENSO) (e.g., Webster and Yang, 1992; Ailikun and Yasunari, 21; Wang and Fan, 1999; Lang and Barros, 24). However, only few studies have examined the spatial and temporal variability of precipitation over Nepal, and most of the rain gauges in Nepal s mountainous areas are located at valley bottoms (Lang and Barros, 22). Consequently, precipitation variability over Nepal remains poorly understood. * Correspondence to: Kimpei Ichiyanagi, Institute of Observational Research for Global Change, Japan Agency for Marine-Earth Science and Technology, 2-1 Natsushima-cho, Yokosuka-city, Kanagawa , Japan. kimpei@jamstec.go.jp Few researchers have investigated the local-scale precipitation patterns in central Nepal because of the difficulty of conducting studies in this mountainous area. Barros et al. (2) examined rainfall in a mountainous area of Nepal, comparing monsoon rainfall measured using rain gauges to Tropical Rainfall Measuring Mission (TRMM) satellite-derived data. They produced a three-dimensional profile of radar-measured rain rates and discussed the interactions between mesoscale convective systems and steep terrain at elevations of 1 2 km. Barros and Lang (23) compared precipitation data observed during the Monsoon Himalayan Precipitation Experiment to data extracted from a global atmospheric reanalysis data set and found that the reanalysis data severely underestimated precipitation. A few studies have investigated how the monsoon and ENSO affect large-scale precipitation patterns. Shrestha (2) analyzed precipitation at 78 stations throughout Nepal and compared the temporal variability in precipitation to climatological parameters over Nepal. Their study revealed a significant relationship between precipitation and the Southern Oscillation Index (SOI), i.e., precipitation was lighter in Nepal when the SOI was low. Lang Copyright 27 Royal Meteorological Society

2 174 K. ICHIYANAGI ET AL. and Barros (22) examined the onset of monsoon in central Nepal in 1999 and 2 and found that the onset was associated with monsoon depressions in the Bay of Bengal. Kansakar et al. (24) used data gathered from 222 stations over Nepal to derive climatological patterns of monthly precipitation, classifying regimes by the shape and magnitude of monthly precipitation. They found that precipitation patterns were controlled by the summer monsoon and by orographic effects induced by the mountain ranges. In this study we investigated spatial distributions of annual and seasonal precipitation, orographic effects, and long-term trends to improve understanding of how the Indian summer monsoon and ENSO affect precipitation over Nepal. meridional), and precipitation rate data at resolution. In this study, these reanalysis data were used to calculate circulation anomalies and indices. We also computed several indices relevant to precipitation over Nepal and to monsoon circulation. The All Indian Rainfall (AIR) index measures monthly averaged precipitation over India. The Indian Institute of Tropical Meteorology provided homogeneous Indian monthly rainfall data sets, and the Climate Prediction Center provided the monthly averaged SOI, defined as the difference between pressures at sea level at Tahiti and Darwin. Precipitation and meteorological indices for Nepal were defined by deviations from monthly averages over the entire period ( ). All data were normalized using their standard deviation. DATA SETS The main data used in this study were amounts of monthly precipitation measured at 274 rain gauge stations throughout Nepal from 1987 to Precipitation amounts observed at these stations were extracted from data books published by His Majesty s Government of Nepal, Department of Hydrology and Meteorology (DHM, 1992, 1997, 1999). We used the data for a specific station only if data were available for more than 8% of the entire period. The National Centers for Environmental Prediction/ National Center for Atmospheric Research (NCEP/ NCAR) global atmospheric reanalysis data set (Kalnay et al., 1996) includes surface temperature, outgoing longwave radiation (OLR), 8-hPa winds (zonal and RESULTS Precipitation in relation to elevation Some previous studies of the Himalayas have considered orographic effects on precipitation (Singh et al., 199; Singh and Kumar, 1997). Therefore, we examined the variability of precipitation with elevation. Figure 1 presents the locations of rain gauge stations in Nepal. Station elevations range from 7 to 41 m, and many stations are concentrated in central Nepal. We calculated the average annual precipitation for individual rain gauge stations and also partitioned the station data into -m elevation bins. Figure 2 presents the average annual precipitation and the number of stations per specific -m elevation increments. More than 3 stations are located at elevations between 1 and 2 m, and fewer than 3. Rain gauge stations in Nepal 3N E 81E 82E 83E 84E 8E 86E 87E 88E 89E Figure 1. Rain gauge stations of Nepal. Crosses and open circles indicate stations located below and above elevations of 3 m, respectively. Copyright 27 Royal Meteorological Society Int. J. Climatol. 27: (27) DOI: 1.12/joc

3 PRECIPITATION IN NEPAL BETWEEN 1987 AND Prec. (mm/yr) num. stations elevation (m) Figure 2. Annual precipitation and the number of stations in -m elevation bins over Nepal. Maximum, mean, and minimum annual precipitations are shown in the upper panel. 6 (a) Western (8 82) 6 (b) Central (83 8) 6 (c) Eastern (86 88) Precipitation (mm/yr) elevation (m) elevation (m) elevation (m) 4 Figure 3. Relationships between annual precipitation and elevation divided into western (8 E 83 E), central (83 E 86 E), and eastern (86 E 89 E) Nepal. 1 stations are located between 2 and 4 m. Only one station is above 4 m. Annual precipitation over 1 years ( ) was averaged for each station. Maximum annual precipitation increased linearly with altitude from 3 to mm/yr for elevations below 2 m, and decreased to 1 mm/yr for elevations above 2 m. Mean annual precipitation was almost 2 mm/yr below 3 m. Singh and Kumar (1997) summarized the orographic effects found in previous studies. Some studies found maximum precipitation at 2 2 m and a subsequent decrease with elevation. Figure 3 presents the relationships between annual precipitation and elevation divided into three regions: western (8 E 82 E), central (83 E 8 E), and eastern (86 E 88 E) Nepal. A negative relationship was found only for western Nepal, where precipitation decreased by 1 mm for -m elevation increments. The correlation coefficient was approximately.4, indicating statistical significance. In western Nepal, maximum value was below 2 mm/yr, whereas central and eastern Nepal had maximum values of approximately mm/yr. In central Nepal, maximum values increased and minimum values decreased below 2 m. Precipitation ranged from 1 to 3 mm/yr for elevations below 3 m in eastern Nepal. Spatial distribution Station data from 1987 to 1996 were averaged on a grid with a horizontal resolution of.2 in both longitude and latitude to examine the spatial distribution of precipitation. Figure 4 presents the spatial distribution of mean annual precipitation. Precipitation was relatively heavy (more than 2 mm/yr) over central Nepal and eastern Nepal near Bhutan. Kansakar et al. (24) described zones of heavy precipitation near Pokhara and northeast of the Kathmandu Valley. Annual precipitation was less than 1 mm/yr in northwestern Nepal, where elevations exceed 3 m. Most of Nepal had an average annual precipitation of 1 2 mm/yr. Figure presents the spatial distribution of seasonal precipitation data composed of monthly precipitation averaged over three months. The four seasons include winter (December to February), pre-monsoon (March to May), monsoon (June to August), and post-monsoon Copyright 27 Royal Meteorological Society Int. J. Climatol. 27: (27) DOI: 1.12/joc

4 176 K. ICHIYANAGI ET AL. 3. Annual Precipitation (mm/year) 3N E 81E 82E 83E 84E 8E 86E 87E 88E 89E Figure 4. Annual precipitation in Nepal averaged from 1987 to This figure is available in colour online at (September to November). Figure 6 presents seasonal wind and precipitation features revealed by NCEP/NCAR reanalysis data. Horizontal and meridional winds and precipitation rates were averaged over the same period (from 1987 and 1996). In winter, total monthly precipitation exceeded 4 mm/month over western Nepal but was less than 2 mm/month over eastern Nepal. Figure (a) illustrates clearly that precipitation over western Nepal was heavier than precipitation over central and eastern Nepal only in winter. Figure 6(a) shows that a westerly wind dominated over the area north of latitude 2 N and that precipitation rates exceeded mm/month in northwestern Nepal along the Himalayan range. In contrast, western Nepal had less precipitation than central and eastern Nepal during the pre-monsoon, monsoon, and post-monsoon seasons. During these seasons, a strong southwesterly wind from the Bay of Bengal supplied heavy precipitation to Nepal. Figure (b) shows that in the pre-monsoon season, the western region of Nepal had less than mm/month of precipitation, while the central and eastern areas had more than mm/month. As shown in Figure 6(b), a westerly wind dominated over the area of latitude 2 N 3 N, and the precipitation rate was more than mm/month in northwestern Nepal in the pre-monsoon season. The precipitation rate was also greater than 1 mm/month in areas east of Nepal and Bangladesh. During the monsoon season, total precipitation exceeded 2 mm/month in all areas except northwest Nepal, as shown in Figure (c). Precipitation exceeded 8 mm/month at only two grids in central and eastern Nepal. As illustrated in Figure 6(c), a strong westerly wind dominated the area south of latitude 2 N during the summer monsoon season, from the Arabian Sea to the Bay of Bengal through the Indian subcontinent. Precipitation rates were more than 3 mm/month over the west coast of India and more than 4 mm/month over western Nepal and the west coast of Myanmar. During the post-monsoon season, precipitation was less than 1 mm/month over western Nepal and more than 1 mm/month over central and eastern Nepal, as shown in Figure (d). Even though Nepal has a zone of divergence, the precipitation rate was still over mm/month in southern Nepal, as shown in Figure 6(d). Precipitation over the mountains of northwest Nepal was less than 2 mm/month during the monsoon season (Figure (c)) and less than mm/yr during the post-monsoon season (Figure (d)). Kansakar et al. (24) classified long-term mean precipitation data for specific stations by shape and magnitude. Their results indicated that July August peaks were typical over western Nepal, that central Nepal had heavier precipitation, and that weather systems in the west supplied winter precipitation to the mountains of northwestern Nepal. The annual and seasonal precipitation patterns found in the current study resemble the results of previous studies (e.g., Chalise et al., 23; Kansakar et al., 24). However, this is the first study to reveal a local maximum precipitation over western Nepal in winter. DISCUSSION Long-term trends To examine long-term trends of precipitation in Nepal, standardized anomalies in monthly precipitation for all grid data were averaged for Figure 7 presents the time series of precipitation anomalies Copyright 27 Royal Meteorological Society Int. J. Climatol. 27: (27) DOI: 1.12/joc

5 PRECIPITATION IN NEPAL BETWEEN 1987 AND Precipitation (mm/month) 3. 3N DJF (a) 8E 81E 82E 83E 84E 8E 86E 87E 88E 89E 3. 3N MAM (b) 8E 81E 82E 83E 84E 8E 86E 87E 88E 89E 3. 3N JJA (c) 8E 81E 82E 83E 84E 8E 86E 87E 88E 89E 3. 3N SON (d) 8E 81E 82E 83E 84E 8E 86E 87E 88E 89E Figure. Seasonal precipitation in Nepal for (a) December February, (b) March May, (c) June August, and (d) September November. This figure is available in colour online at com/ijoc over Nepal but does not reveal any significant long-term trends. Decreases occurred in and , and increases occurred in 1992 and 199. Intra-seasonal variation was low in but high in and Shrestha et al. (2) analyzed all the precipitation records for Nepal for ; their results also revealed no significant long-term trends. Standardized anomalies in monthly precipitation at specific stations were also examined to test for longterm trends. Kendall s rank correlation was used to test for significance in observed trends; Figure 8 presents stations with significant trends. Some stations in western and central Nepal showed an increase in precipitation; one station in central Nepal was the only one to show a decrease. Correlation coefficients at most stations ranged from.2 to.2, and long-term trends were not statistically significant. Correlations with climatological indices Many previous studies have related monsoon precipitation to ENSO (e.g., Webster and Yang, 1992; Ailikun and Yasunari, 21). Kawamura (1998) discussed the indirect effects that both anomalous sea-surface temperature (SST) forcing and land ocean thermal contrasts associated with ENSO had on the Asian summer monsoon. Shrestha et al. (2) showed a strong relationship between precipitation over Nepal and the SOI in that less precipitation fell over Nepal during the ENSO warm phases. The relationship between the SOI and precipitation over Nepal was much stronger than the relationship between the SOI and AIR, especially after 197. We examined the relationship between precipitation over Nepal during the summer monsoon season (from June to September) and climatological indices (the AIR and SOI). Correlation coefficients were calculated to relate a standardized anomaly of monthly precipitation for a specific station to the AIR and SOI. Figure 9 presents stations with significant correlations. Most stations having positive correlation with the AIR were in western Nepal, while a few stations in eastern Nepal were negatively correlated with the AIR, as shown in Figure 9(a). Figure 9(b) shows that some stations in western and eastern Nepal were positively correlated with the SOI, but none appeared to be negatively correlated. A composite analysis was used to elucidate the largescale impact of the AIR and SOI. High-phase years for the AIR were 1988, 199, and 1994; low-phase years were 1987, 1993, and High-phase years for the SOI were 1988, 1989, and 1996; low-phase years were 1987, 1991, and Figures 1 and 11 show the differences in surface temperature, 8-hPa winds, OLR, and precipitation rates between low and high phases for the AIR and SOI, respectively. As shown in Figure 1(a), a negative temperature anomaly was observed over the Indian subcontinent. Figure 1(b) shows that cyclonic circulation over the Arabian Sea and the Indian subcontinent (centered at 2 N and 7 E) corresponded to a temperature anomaly. Figure 1(c) indicates a negative OLR anomaly observed over northern India, while Figure 1(d) shows the positive precipitation rate observed over India and western Nepal. The negative precipitation rate observed over eastern Nepal corresponded to the northerly wind anomaly (Figure 1(b)). These results suggest that moist air transported from the Arabian Sea supports precipitation over western Nepal, whereas cold dry air from the Tibetan Plateau suppresses precipitation over eastern Nepal. Therefore, monsoon precipitation over western and eastern Nepal is positively and negatively correlated with the AIR, respectively. Kripalani et al. (1996) also noted that monthly rainfall changes over Kathmandu corresponded to rainfall variations over northern India. Copyright 27 Royal Meteorological Society Int. J. Climatol. 27: (27) DOI: 1.12/joc

6 178 K. ICHIYANAGI ET AL. 4 Prec. & UV8 (DJF) 4 Prec. & UV8 (JJA) 4N 4N N 3N N 2N N N E E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E E E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E (a) 1 (c) 2 4 Prec. & UV8 (MAM) 4 Prec. & UV8 (SON) 4N 4N 3 3N N N 2 2N N 1N E E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E E E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E (b) 8 (d) 6 Figure 6. Seasonal wind and precipitation rate in Nepal over the four periods (for periods see Figure ). Anomaly / STD Nepal Precipitation ( ) Figure 7. Time series of standardized precipitation anomalies over Nepal. In contrast, Figure 11(a) indicates no temperature anomaly. Figure 11(b) shows that anomalies of both northwesterly and southerly winds combined over the Bay of Bengal into a strong westerly wind anomaly over Indochina. Figure 11(c) and (d) present the anomalies of negative OLR and positive precipitation rates observed over the Bay of Bengal and South China Sea. In Nepal, however, no precipitation anomalies were observed. Shrestha et al. (2) found no good agreement between precipitation fluctuations over Nepal and India. When simultaneous correlations were performed in the present study, the results indicated that correlation coefficients were low throughout Nepal. Ichiyanagi and Yamanaka (2) found that an anomaly in precipitation for Bangkok in May was a response to the Niño 3 SST anomaly in March. Lag correlation analysis may yield a better understanding of the relationship between ENSO and the Asian monsoon. Copyright 27 Royal Meteorological Society Int. J. Climatol. 27: (27) DOI: 1.12/joc

7 PRECIPITATION IN NEPAL BETWEEN 1987 AND Long term trend (kendall's Rank Test) 3N E 81E 82E 83E 84E 8E 86E 87E 88E 89E Figure 8. Stations exhibiting increasing and decreasing trends by Kendall s rank test. Open and closed circles indicate correlation coefficients of more than.2 and less than.2, respectively. 3. 3N (a) Correl. Monsoon Rainfall (JJAS) and AIR E 81E 82E 83E 84E 8E 86E 87E 88E 89E 3. 3N (b) Correl. Monsoon Rainfall (JJAS) and SOI E 81E 82E 83E 84E 8E 86E 87E 88E 89E Figure 9. Stations that correlated well with (a) All Indian Rainfall (AIR) and (b) Southern Oscillation Index (SOI). Solid (open) circles indicate a positive (negative) correlation. Copyright 27 Royal Meteorological Society Int. J. Climatol. 27: (27) DOI: 1.12/joc

8 176 K. ICHIYANAGI ET AL. 4 (a) Diff. Temp. (AIR) 4 (c) Diff. OLR (AIR) 4N 4N 3 3 3N N N 1 1N 1. 2N 1 1N E E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E E E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E 4 (b) Diff. UV8 (AIR) 4 (d) Diff. Prec. (AIR) 4N 4N 3 3 3N 3N N 2N N E E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E E E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E 2 Figure 1. Composite differences between low and high All Indian Rainfall (AIR) phases in (a) surface temperature, (b) 8-hPa winds, (c) outgoing longwave radiation (OLR), and (d) precipitation rates during the monsoon season (June September). 1N 3 3 CONCLUSIONS We statistically analyzed monthly precipitation data from 274 gauges in Nepal between 1987 and 1996 to determine spatial and temporal variability in precipitation. More than 3 stations were at elevations between 1 and 2 m, while fewer than 1 stations were above 2 m. Maximum annual precipitation increased from 3 to mm/yr as elevation increased to 2 m, and then decreased to 1 mm/yr at elevations from 2 to 3 m. A negative relationship was observed only in western Nepal. Precipitation decreased by 1 mm for specific -m elevations. Mean annual precipitation was less than 1 mm/yr over the mountains in northwestern Nepal and more than 3 mm/yr in central Nepal. Seasonal precipitation from December to February was greater over western Nepal than eastern Nepal. In contrast, western Nepal was drier from March to November. To investigate long-term trends in Nepal s precipitation, we averaged the standardized anomalies of monthly precipitation for all grid data from 1987 to 1996 and examined the averages by applying Kendall s rank correlation to specific stations. These analyses did not reveal any general trends, although some stations in central and eastern Nepal exhibited an increasing trend. One station in central Nepal showed a decreasing trend. We also investigated the relationships between precipitation during the summer monsoon and climatological indices for specific months and for the entire observational period. Precipitation in western Nepal was positively correlated with the AIR, while precipitation in eastern Nepal was negatively correlated. Monsoon precipitation in both western and eastern Nepal was positively correlated with the SOI. The NCEP/NCAR reanalysis data were used to analyze composite differences in temperature, 8-hPa winds, OLR, and precipitation rates between low and high phases of the AIR. The results indicated that moist air transported from the Arabian Sea supports precipitation over western Nepal, whereas cold dry air from the Tibetan Plateau suppresses precipitation over eastern Nepal. With regard to the SOI, anomalies of strong westerly winds, negative OLR, and positive precipitation rates were observed over the Bay of Bengal. However, no precipitation anomalies were observed over Nepal. Lag correlation analysis is needed for a more comprehensive investigation of how precipitation variability in Nepal is related to ENSO. Copyright 27 Royal Meteorological Society Int. J. Climatol. 27: (27) DOI: 1.12/joc

9 PRECIPITATION IN NEPAL BETWEEN 1987 AND (a) Diff. Temp. (SOI). 3 (c) Diff. OLR (SOI) 3N 2. 3N 2 2N 2N N 1N EQ EQ S S 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E 11E 12E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E 11E 12E 3 (b) Diff. UV8 (SOI) 3 (d) Diff. Prec. (SOI) 3N 3N 2 2N 2 2N N 1N EQ EQ S S 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E 11E 12E 6E 6E 7E 7E 8E 8E 9E 9E 1E 1E 11E 11E 12E 3 Figure 11. Composite difference between low and high Southern Oscillation Index (SOI) phases in (a) surface temperature, (b) 8-hPa winds, (c) outgoing longwave radiation (OLR), and (d) precipitation rates during the monsoon season (June September). ACKNOWLEDGEMENTS The authors thank the staff of Nepal s Department of Hydrology and Meteorology (DHM) for their cooperation with the research and for providing the data books published by DHM. The Indian monthly rainfall data set and the Global land 1-km base elevation data set were provided by the Indian Institute of Tropical Meteorology and Climate Prediction Center and the National Geophysical Data Center, respectively. This research was supported by the Institute of Observational Research for Global Change (IORGC) in FY REFERENCES Ailikun B, Yasunari T. 21. ENSO and Asian summer monsoon: persistence and transitivity in the seasonal march. Journal of the Meteorological Society of Japan 79(1): Barros AP, Lang TJ. 23. Monitoring the monsoon in the Himalayas: observations in central Nepal, June 21. Monthly Weather Review 131: Barros AP, Joshi M, Putkonen J, Burbank DW. 2. A study of the 1999 monsoon rainfall in a mountainous region in central Nepal using TRMM products and rain gauge observations. Geophysical Research Letters 27: Chalise SR, Kansakar SR, Rees G, Croker K, Zaidman M. 23. Management of water resources and low flow estimation for the Himalayan basins of Nepal. Journal of Hydrology 282: 2 3. DHM (Department of Hydrology and Meteorology) Precipitation Records of Nepal ( ), His Majesty s Government of Nepal, Kathmandu, Nepal. DHM (Department of Hydrology and Meteorology) Precipitation Records of Nepal ( ), His Majesty s Government of Nepal, Kathmandu, Nepal. DHM (Department of Hydrology and Meteorology) Precipitation Records of Nepal ( ), His Majesty s Government of Nepal, Kathmandu, Nepal. Hahn DG, Shukla J An apparent relationship between Eurasian snow cover and Indian monsoon rainfall. Journal of the Atmospheric Sciences 33: Ichiyanagi K, Yamanaka MD. 2. Interannual variation of stable isotopes in precipitation at Bangkok in response to El Niño Southern Oscillation. Hydrological Processes 19: Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandin L, Iredell M, Saha S, White G, Woollen J, Zhu Y, Chelliah M, Ebisuzaki W, Higgins W, Janowiak J, Mo KC, Ropelewski C, Wang J, Leetmaa A, Reynolds R, Jenne R, Joseph D The NCEP/NCAR 4-year reanalysis project. Bulletin of the American Meteorological Society 77: Kansakar SR, Hannah DM, Gerraed J, Rees G. 24. Spatial pattern in the precipitation regime of Nepal. International Journal of Climatology 24: Kawamura R A possible mechanism of the Asian summer monsoon ENSO coupling. Journal of the Meteorological Society of Japan 76(6): Kripalani RH, Inamdar S, Sontakke NA Rainfall variability over Bangladesh and Nepal: comparison and connections with features over India. International Journal of Climatology 16: Copyright 27 Royal Meteorological Society Int. J. Climatol. 27: (27) DOI: 1.12/joc

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