Spatial and temporal patterns of land surface temperature in the Mekong Basin

Abstract

Land surface temperature (LST) is an essential part of the surface energy budget and can be used as a measure for climate variability and change, given that regular measurements on a broad spatial scale are available. The MODIS (Moderate Resolution Imaging Spectroradiometer) sensor offers a 13 years’ time series, which enables the analysis of spatial patterns along with the temporal evolution of the variable. Area of interest is the Mekong Basin (MB). It was analysed using MODIS LST data with a temporal granularity of 8-days. LST prove to be strongly dependent on the topography. 42% of daytime LST could be explained by topographic height in summer. In winter and generally in the night time scenes topography could explain 89-97% of the LST distribution. For further analysis the area of interest was divided into six physiographic homogenous regions. The mean temperature and the annual maximum and minimum values of LST are different for the various regions. Low temperatures coupled with large magnitudes are predominantly found in the high-lysing Tibetan Plateau, whereas the southern regions show high mean temperatures along with low magnitudes. There is a weak year-to-year variability of LST (regional 8-day daytime/night time deviations lower than 4°C/6°C) in all regions. However, over the Tibetan Plateau regional 8-day daytime/night time deviations reach 6°C and 18°C. Apart from the topography, LST is influenced by land use. As such, land use changes influence the LST pattern as is shown in this research on the example of deforestation in parts of Cambodia.