Effects of Evapotranspiration on Regional Land Surface Temperature in an Arid Oasis Based on Thermal Remote Sensing

Evapotranspiration (ET) is crucial to arid and semiarid environments because it substantially affects the energy and water cycles. Based on the estimation of continuous ET from barren or sparsely vegetated areas, this letter investigated how ET affects the regional land surface temperature (LST) in the Shiyanghe river catchment area, a typical inland river catchment in Northwest China. ET was estimated during 2008-2011 using a three-temperature model and MODIS data sets. LST was retrieved from the MODIS product (MOD11A2). Results taken from transects that began in the oasis area and ended in the desert reveal that ET decreased, with the daily average ET in the oasis being approximately 1.4 mm larger than that in the desert. By contrast, the LST in the oasis was 8 K lower than that in the desert. Statistical results suggested that ET and LST showed a negative relationship (R-2 = 0.83). Further analysis showed that the correlation was strongly dependent on the water availability in barren or sparsely vegetated areas. It is concluded that in water-limited barren or sparsely vegetated regions, the negative correlation between ET and LST may provide alternative information for water management, such as identifying groundwater recharge in arid regions.