A Climate Change Study: Downscaling of Climatic Parameters and Their Assessment Over East Rathong Glacier of Eastern Himalayan Region

In this study monthly Temperature Lapse Rates and basic downscaling technique of subtracting means are used to construct temperature (T) series over East Rathong glacier by using multiple data sets from Automatic Weather Stations (AWS) at Himalayan Mountaineering Institute (HMI), Gangtok Indian Meteorological Department (IMD), Yuksum and ERA5reanalysis data. Precipitation (P) over glacier is estimated using Gangtok IMD data and downscaled ERA5 data. The P data is downscaled using local scaling factor method. Change in volume of 0.180 km³ (from 1962 to 2020) estimated using satellite data are used to construct Mass Balance (MB) series for the glacier. It is observed that the glacier is losing its mass with increasing T, Aerosol Optical Depth (AOD) (from 0.1 in 1980 to 0.2 in 2020), and increasing Pmainly during June-July-August months when temperatures are already high. This study is important as it used multiple data sets along with field data extracted from the literature to study climatic impacts on East Rathong glacier. Data generated from this study may be used in mass balance projection of the glaciers in the absence of field data.