Spatio-temporal variation of land surface temperature and temperature lapse rate over mountainous Kashmir Himalaya

摘要

In this study,Land Surface Temperature (LST) and its lapse rate over the mountainous Kashmir Himalaya was estimated using MODIS data and correlated with the observed in-situ air temperature (Tair) data.Comparison between the MODIS LST and Tair showed a close agreement with the maximum error of the estimate ±1℃ and the correlation coefficient ＞0.90.Analysis of the LST data from 2002-2012 showed an increasing trend at all the selected locations except at a site located in the southeastern part of Kashmir valley.Using the GTOPO30 DEM,MODIS LST data was used to estimate the actual temperature lapse rate (ATLR) along various transects across Kashmir Himalaya,which showed significant variations in space and time ranging from 0.3℃ to 1.2℃ per 100 m altitude change.This observation is at variance with the standard temperature lapse rate (STLR) of 0.65℃ used universally in most of the hydrological and other land surface models.Snowmelt Runoff Model (SRM) was used to determine the efficacy of using the ATLR for simulating the stream flows in one of the glaciated and snow-covered watersheds in Kashmir.The use of ATLR in the SRM model improved the R2 between the observed and predicted streamflows from 0.92 to 0.97.It is hoped that the operational use of satellite-derived LST and ATLR shall improve the understanding and quantification of various processes related to climate,hydrology and ecosystem in the mountainous and data-scarce Himalaya where the use of temperature and ATLR are critical parameters for understanding various land surface and climate processes.