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This work addresses the remotely sensed urban heat sink formation in Santiago City, Chile. The main aim was to analyse the relationship that surface temperature exhibits with land cover types, as well as with vegetation cover fraction, surface moisture and albedo of Santiago City and its rural surroundings. Information was extracted from the processing of Landsat Enhanced Thematic Mapper Plus (ETM + ) data. Surface temperature of the main land cover classes and correlation coefficients between surface temperature and the above-mentioned surface parameters were analysed. The results show that the hottest surfaces are mainly concentrated in the northern rural valley, wherein the predominance of bare or sparsely vegetated land covers determine a low vegetation cover fraction and surface moisture content. The correlation coefficients obtained confirm the higher warming rate that the rural valley exhibits in comparision with the city temperatures at the image acquisition time, which is one of the main causes of urban heat sink formation.

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Abstract. Remote sensors face challenges in characterizing mountain permafrost and ground thermal conditions or mapping rock glaciers and debris-covered glaciers. We explore the potential of thermal imaging and in particular thermal inertia mapping in mountain cryospheric research, focusing on the relationships between ground surface temperatures and the presence of ice-debris landforms on one side and land surface temperature (LST) and apparent thermal inertia (ATI) on the other. In our case study we utilize ASTER daytime and nighttime imagery and in-situ measurements of near-surface ground temperature (NSGT) in the Mediterranean Andes during a snow-free and dry observation period in late summer. Spatial patterns of LST and NSGT were mostly consistent with each other both at daytime and at nighttime. Daytime LST over ice-debris landforms was decreased and ATI consequently increased compared to other debris surfaces under otherwise equal conditions, but NSGT showed contradictory results, which underlines the complexity and possible scale dependence of ATI in heterogeneous substrates with the presence of a thermal mismatch and a heat sink at depth. While our results demonstrate the utility of thermal imaging and ATI mapping in a mountain cryospheric context, further research is needed for a better interpretation of ATI patterns in complex thermophysical conditions.