Spatial and temporal analysis of surface temperature in the Apacheta micro-basin using Landsat thermal data

Abstract

High Andean ecosystems, such as grasslands and peatlands, are fragile and, due to the effects of climate change, their sustainability is being jeopardized. A key factor hampering sustainable management efforts from the government and communities, is the lack or scarcity of in-situ eco-hydrological and climate data. In that sense, remote sensing techniques offers a powerful alternative for the assessment of the evolution of these ecosystems, by providing a holistic view of the territory. The objective of this work is to determine both the spatial and temporal evolution of the local atmospheric temperature of the Apacheta micro-basin in Ayacucho over the past 34 years, using the soil surface temperature (SST) as a proxy. For this, thermal data of Landsat series (TM, ETM+ and TIRS sensors), covering the period from 1985 to 2018, were used. The TSS estimates were made from the emissivity correction of the brightness temperatures at the top of the atmosphere, considering the negligible atmospheric effect due to the conditions of high atmospheric transmissivity in the study area. The results show a positive trend of the SST with an increase of 4.9 °C, equivalent to 27.5% of the SST. Trends are higher (5.8 °C) in the snowy areas (equivalent to 35.3% of the TSS in the whole micro-basin). The SST in the snow area explains the 83.6% of the behavior of the snow cover derived by the NDSI, with a decreasing surface as SST increase.