Seasonal Characteristics of Temperature Gradient in a Glaciated Catchment in Eastern Himalaya

With climatic information from four stations in Rathong Chu valley for the period from 2017 to 2018, this study presents monthly and seasonal characteristics of the temperature lapse rate (TLR) in the eastern Himalayas. The station heights utilised in the study ranged from 1,742 to 4,450 m. The TLRs were assessed utilising a linear regression model. The mean yearly TLR for eastern Himalaya is less sheer (-0.52°C/100 m) beneath the tree line than (-0.47°C/100 m) over the tree line. The series of TLR exhibits two peaks in a year which confirms the distinctive controlling elements in the individual seasons. The highest TLR was found to be -0.60 °C/100 m during the pre-monsoon season below the tree line and -0.64 °C/100 m above the tree line. The post-monsoon has the second highest lapse rate change beneath the tree line (-0.58 °C/100 m) and in the monsoon (-0.57 °C/100 m) above the tree line. The minimum lapse rates were observed in the winter season below the treeline (-0.42 °C/100 m) and (-0.18 °C/100 m) above the tree line. The outcomes of this study add to the insight of elevation-dependent warming affected by worldwide climate change. Results also suggest that the climate and glacier modelling using the satellite temperature records or by applying the environmental lapse rate on temperature records from low altitudes may not be presenting the actual temperature trends.