Evaluating landsurface temprature variation and its responses to climate
change and human activities ------A case study of the Yarlung Zangbo
River, southeastern Tibetan Plateau
Abstract
The Yarlung Zangbo River Basin (YZRB), located in the Qinghai-Tibetan
Plateau, has been dramatically affected by global warming. In recent
decades, serving as the indicator of coupled vegetation growth and
climate variation, the spatiotemporal land surface temperature has been
changed substantially by changes in environmental factors while greening
spreading. In this study, we evaluated the components of water and
energy cycle during 1980-2015 based on the VIC model, one of the widely
recognized and applicated distributed hydrological model. The
fluctuation of LST was examined and the influence of environmental
elements on LST was identified. The results showed that VIC model
performed a high adaptability in applying and conducting in YZRB with R
2 over 0.7 and Er at 5.03%. Climate factors were
increasing while human activities stayed stable in YZRB by our modeling.
In addition, climate factors (precipitation, evapotranspiration,
temperature) and underlying factors (soil moisture, NDVI, Albedo) were
detected as influencing factors of LST. In YZRB, the greening was
witnessed while LST showed an increasing trend. By distinguishing the
climate and human activities on LST, ET and NDVI are two dominant
factors effecting LST. From 1980 to 1995, LST was mainly affected by
climate and its contribution rate was 70.36%. After 1995, LST was
affected by human activities, and its contribution rate was 55%.
Grassland with medium cover showed the potential of a cooling influence.
Among all the environmental factors, Albedo showed a negative and a
lagged behind effect on LST. Temp, P and ET were positively related to
LST and displayed changes that are relatively in phase. SM, NDVI, were
detected as leading the changes in LST, positively. Our study
contributes to clarifying the mechanisms influencing LST in
high-altitude and high-latitude regions under the global greening and is
fundamental for socio-economic development in alpine mountainous
regions.