Surface Temperature Estimation from Landsat ETM Data for a part of the BaspaBasin, NW Himalaya, India

Introduction K. Babu Govindha RAJ and Kevin FLEMING Surface Temperature Estimation from Landsat ETM Data for a part of the Baspa Basin, NW Himalaya, India 19 Bulletin of Glaciological Research ( ) Japanese Society of Snow and Ice National Remote Sensing Agency (NRSA) Balanagar, HyderabadAndhra Pradesh, India Department . Physics of the Earth GeoForschungsZentrum Potsdam Potsdam, D, Germany (Received May , ; Revised manuscript accepted September , ) This paper presents results of extracting surface temperatures from Landsat ETM Thermal Band (Band , Low gain) data for the Baspa River Basin, Himachal Pradesh, India. Initially, Top of Atmospheric (TOA) radiance is extracted from the digital number (DN) values. The TOA radiance is then converted to surface radiance by applying the Reference Channel Emissivity (RCE) method, assuming the emissivity of the study area is constant ( . , the emissivity of glacier ice). The surface temperature is then extracted from the surface radiance. Based on images from June and October , mean temperatures of . and . , respectively, are inferred. The extracted temperature data were compared to observed temperatures and showed a good correlation, with di erences of . tains the largest concentration of glaciers ( ), followed by the Ganges ( ) and Brahmaputra ( ) (WWF, ). Glaciation has occurred in the HimaAdvances in space technology has increasingly laya over the last million years, with recent studies allowed the use of satellite data to study complex indicating about glacial periods alternating with physical processes on the Earth’s surface. In the field warmer interglacial periods (Raina, ). of glaciology, various types of remote sensing studies Today, in the Himalayan region glaciers are dishave been successfully undertaken, including examintributed in di erent climatic zones. The mean daily ing the movements of glaciers using radar interferoair temperature is low in the month of January and metry (Rignot and Kanagaratnam, ), and detectrises during the pre-monsoon period (February to ing changes in the duration and onset of the ablation May), with maximum average daily temperatures durseason ( Smith , ). In Himalaya, glacier ing late May and early June, while during the postretreat and mass balance assessments using the accumonsoon (October to January) season, mean daily air mulation area ratio (AAR) method have been attemperature decreases. The Himalaya cause changes tempted. (Kulkarni , ; Kulkarni ). in the air masses crossing the region, resulting in a While the mapping of glaciers, retreat of one of the special microclimate in the region. The southern glaciers in the Baspa basin using remote sensing has plains possess sub-tropical climate with the middle also been demonstrated (Philip and Sah, ). hills having a temperate climate and an alpine climate The Himalaya is one of the youngest mountain in the high mountain ranges. The mean level of glasystems on Earth, and has a direct influence on the ciation varies from to m above mean sea climate, hydrology and environment of the Indian level (m.s.l.). The Himalayan glaciers vary in form subcontinent. It has the largest concentration of glafrom niche, cirque, simple-basin and compound-basin ciers outside the polar regions, which covering about glaciers. Glaciers in the Himalayas di er from their km area and provide glacier stored water to the counterparts in other parts of the world being high great Indian rivers, the Ganges, Indus and Brahmapudirty and debris covered in the ablation area. The tra. Between these three basins, the Indus basin consnout region is usually marked by the formation of an e.g. et al.