Abstract
The presence and extent of permafrost in the Himalaya, which is a vital component of the cryosphere, remains severely under-researched with its future climatic-driven trajectory only partly understood and the future consequences on high-altitude ecosystem tentatively sketched out. Previous studies and available permafrost maps for the Himalaya relied primarily upon the modelled meteorological inputs to further model the likelihood of permafrost. Here, as a maiden attempt, we have quantified the distribution of permafrost at 30 m grid-resolution in the Western Himalaya using observations from multisource satellite datasets for estimating input parameters, namely temperature, potential incoming solar radiation (PISR), slope, aspect and land use, and cover. The results have been compared to previous studies and have been validated through field investigations and geomorphological proxies associated with permafrost presence. A large part of the study area is barren land (~69%) due to its extremely resistive climate condition with ~62% of the total area having a mean annual air temperature of (MAAT) <1 °C. There is a high inter-annual variability indicated by varying standard deviation (1–3 °C) associated with MAAT with low standard deviation in southern part of the study area indicating low variations in areas with high temperatures and vice-versa. The majority of the study area is northerly (~36%) and southerly (~38%) oriented, receiving PISR between 1 and 2.5 MW/m2. The analysis of permafrost distribution using biennial mean air temperature (BMAT) for 2002-04 to 2018-20 suggests that the ~25% of the total study area has continuous permafrost, ~35% has discontinuous permafrost, ~1.5% has sporadic permafrost, and ~39% has no permafrost presence. The temporal analysis of permafrost distribution indicates a significant decrease in the permafrost cover in general and discontinuous permafrost in particular, from 2002-04 to 2018-20, with a loss of around 3% for the total area (~8340.48 km2). The present study will serve as an analogue for future permafrost studies to help understand the permafrost dynamics associated with the effects of the recent abrupt rise in temperature and change in precipitation pattern in the region.
Highlights
IntroductionOf the land surface of the northern hemisphere [2]
The major objectives of our work are: (1) to systematically analyze the key climatic and topographic parameters controlling occurrence of permafrost such as temperature, precipitation, incoming solar radiation, slope and aspect derived from multisource multi-temporal remote sensing data; (2) to collectively integrate these variables in analytical hierarchy process (AHP)-based framework to get a robust spatial distribution of permafrost; (3) to compare and validate the results with ground/field observations and available published results in the study area and; (4) to create a permafrost distribution map for the parts of the Western Himalaya
The average annual LST were converted to the mean annual air temperature (MAAT) following the statistically significant equations developed by Singh et al [71] for the different elevation and precipitation zones of the Western Himalaya
Summary
Of the land surface of the northern hemisphere [2] This integral cryospheric component has been distinguished as one of the important indicators of global climate change within the international framework of the Global Climate Observing System in World Meteorological. The thawing of permafrost can have diverse and widespread impacts on society, such as an increase in landslides and land degradation due to destabilization of slopes [6,7,8,9], ground subsidence [10,11,12], changes in subsurface hydrology [13,14,15], damage to infrastructure [16,17], and change in sediment load of rivers [18]. As the permafrost thaws, it releases greenhouse gases from the stored soil organic carbon, which creates positive feedback and further amplifies the rate of rise in annual average temperature [19,20,21]. Disaster Risk Reduction (Methods, Approaches and Practices); Nibanupudi, H., Shaw, R., Eds.; Springer: Tokyo, Japan, 2015. [CrossRef]
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