Climate Research in Nepal Himalayas Saraju K. Baidya (Department of Hydrology & Meteorology) “Mountains, witnesses of global changes. Research in the Himalaya and Karakoram: SHARE-Asia Project”, November 2005

Physiography

Meteorological Station Network Precipitation 337 Climatic 68 Agro-met 22 Synoptic 9 Aero-Synoptic 6 Total 442 Automatic 16

Spatial Distribution of Mean Monsoon Precipitation (mm) Altitude determines the spatial distribution of rainfall

Climatic Trends in Nepal Shrestha et. al, 1999 Maximum Temperature Trends in the Himalaya ( ) No significant trend in rainfall

Climate Research The glaciological and meteorological observations in Nepal Himalayas started in 1973 and 1974 as the "Glaciological Expedition to Nepal (GEN)". Nepal Himalayas: 2% of World’s Freshwater Nepal Himalayas: 2% of World’s Freshwater Snowmelt:10% of annual flow Snowmelt:10% of annual flow The studies show that these glaciers are retreating at an alarming rate. The studies show that these glaciers are retreating at an alarming rate. Many researches in this field highlight the impacts on water resource management and Glacier lake outburst Floods (GLOF). Many researches in this field highlight the impacts on water resource management and Glacier lake outburst Floods (GLOF).

Activities Operation of 7 Hydrometeorological stations Hydrological and Meteorological data (Elevation m) collection and publication Glacier and glacier lake studies Model development for snow and glacier melt runoff Snow and Glacier Studies (i) Temperature (ii) Relative Humidity (iii) Precipitation (iv) Solar radiation (v) Wind speed/ direction (vi) River stage/discharge (vii) Water equivalent of snow snow Parameters

Gauging Stations, Annapurna Region Automatic Water Level Recorder,Langtang Automatic Weather Station Khumbu

Snow survey for determination of water equivalent of snow Snow pit Snow sampler

Retreat of AX010 Glacier Retreat from Was 30 m

Imja Lake (Khumbu region) SOURCE: WECS SOURCE: DHM 2002 Area: 0.86 Km 2, 14.7% more than in 1999

Nepal Himalayas are highly vulnerable to the climate change. It has wide impact on water resources and agriculture of Nepal His Majesty’s Government (HMG) of Nepal instituted a Country Study program on Climate Change in 1994 under the support of US Country Studies Program. His Majesty’s Government (HMG) of Nepal instituted a Country Study program on Climate Change in 1994 under the support of US Country Studies Program. For the first time in Nepal, General Circulation Models (GCMs) Outputs were used and climate change scenarios were developed. Climate Change Studies

Four models Four models –CCCM: Canadian Climate Centre Model (2 Grid pts.) –GFD3: Geophysical Fluid Dynamics Laboratory R-30 Model (2 Grid pts.) –UK89: United Kingdom Meteorological Office Model (2 Grid pts.) –GISS: Goddard Institute of Space Science Model (1 Grid pt.)

For 2XCO2 (22 stations) For 2XCO2 (22 stations) –Precipitation increase CCCM : 36% GFD3: 67% –Increase in Monsoon season and decrease in dry (winter) season –Temperature increase CCCM: 1.4 o C to 4.1 o C; 2.9 o C GFD3: +1.7 o C to 4.2 o C; 3.1 o C Limitation: low resolution Limitation: low resolution Climate Change Studies

Status of Climate Models in Nepal Rough topography of Nepal requires high resolution models Rough topography of Nepal requires high resolution models Currently Nepal is experimenting on two RCMs Currently Nepal is experimenting on two RCMs – –RegCM3 (ICTP, Italy) – –PRECIS (Hadley Centre, UK) Main aim of these models is to study the impact of climate change Main aim of these models is to study the impact of climate change Currently, we are on the process of validation experiments Currently, we are on the process of validation experiments

75 km 50 km 30 km RegCM3 Results of 1997 June 0 Observation 50 km 75 km

RegCM3: 1997 monsoon Nested 0 Observation Nested: 15 km 75 km

Time required for 1 month simulation Major issues Running RCM Major issues Running RCM –Time constraint to run high resolution models –Computing facilities

Monsoon Study A project was developed in 1999 and number of meteorological stations ranging from 500 m to 4400 m were installed in the Marsyangdi river basin in central Nepal and Monsoon Himalayan Precipitation Experiment (MOHPREX) was carried out during June 2001 to study the interaction of the Himalayas and the Asian summer monsoon Source: Ana P. Barros and Timothy J. Lang (2001)

The mountains act as barriers to the south-easterly monsoon flow from BOB and consequently low level convergence occurs. Upslope and upvalley flows reduce this convergence. The upslope flow leads to high level convection and secondary peak in precipitation. with the absence of upslope winds, and prevalent down slope winds, strong convergence of the moist advected monsoon flow occurs which acts to force convection which lead to the nocturnal peak in rainfall in these areas. Source: Monitoring the Monsoon in the Himalayas: Observations in Central Nepal, June 2001, Ana P. Barros and Timothy J. Lang

Concluding Remarks Nepal deserves special attention in climate related research because Nepal deserves special attention in climate related research because –Complex Topography –Himalayas are highly vulnerable to climate change –Himalayas are the water tower for South Asia where most of the poorest people live –Himalayan range plays an important role in Asian Summer Monsoon Need of special research on Climate models in Himalayan regions Need of special research on Climate models in Himalayan regions

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