Dynamics of snow cover and melt-water lakes over Himalaya and Tibetan Plateau using long term MODIS observations (2000-2015)

Abstract:

Himalaya is considered to be water-tower of Asia as melt-water from snow cover and glaciers are feeding major rivers of Asia such as Ganga, Indus, and Brahmaputa. Recent studies on atmospheric conditions (tropospheric temperature) and snow cover over Himalayan range suggest changing regional climatic conditions. Enhanced melting of glaciers is corroborated by reports of increasing number of melt-water lakes. A systematic study of state of high-altitude mountain glaciers and melt-water lakes is required for understanding and forecasting impact of global environmental changes in a regional and local scale. Daily snow cover and snow fraction data derived from Moderate Resolution Imaging Spectroradiometer (MODIS) on-board Terra and Aqua have been used to study intra-annual and inter-annual variation of snow during 2000-2015 over the Himalayan mountain range. Daily MODIS data at 500 m grid resolution show large amount of gaps due to cloud cover. An adaptive Savitzky-Golay polynomial filter have been used to fit the time series of daily data for each grid cell. The missing values in daily images have been filled with calculated values to create daily time series of snow over the study region. Statistical study of the snow cover such as seasonal and yearly count, peak season (magnitude and timing), length of snow deposition and melting season are showing significant changes across Himalayan range. Region wise trend analysis of snow cover have been computed at 95% confidence interval. Enhanced melting rate of snow cover and glaciers in Himalaya and Tibetan Plateau is visible in the form of increasing number and aerial coverage of melt-water lakes. Detailed region wise analysis of total number (count) and aerial coverage of melt-water lakes show conspicuous increasing trend that varies across the study area. Increasing number of new melt-water lakes have been found in the central and eastern Himalayas. Statistical analysis of dynamics of snow cover and melt-water lakes in the study area will be presented in detail. Observed variation in the extent of snow cover and formation of new melt-water lakes represents a changing atmospheric and climatic condition over Himalaya and is also corroborated by the long term temperature trend of the middle troposphere.