Biophysical Impact of Multiple Surface Forcings on Land Surface Temperature Over Eastern China

Over the past decades, human activities have directly or indirectly driven the land surface changes in eastern China. These anthropogenic forcings could trigger biochemical feedback and alter the surface biophysical properties, thus affecting local temperature. However, the latter is recognized as the "noise" and ignored when assessing historical or future climate. Here, we adopt the "observation minus reanalysis" (OMR) method to isolate the biophysical temperature footprint of multiple surface changes in eastern China over 2001-2018, using remote sensing land surface temperature and reanalysis skin temperature. A spatial regression model was used to separate the contributions from different processes. We find the biophysical feedbacks of surface changes have an annual cooling effect of -0.072 K/decade in eastern China, and the contributions from urban expansion, agricultural development, and natural vegetation greening are 0.042, -0.042, and -0.072 K/decade, correspondingly. The Northeast Plain shows agricultural activities induced cooling of -0.040 K/decade; the Loess Plateau shows natural vegetation recovery dominated cooling of -0.145 K/decade; the Huang-Huai-Hai Plain demonstrates a predominant urbanization warming effect of 0.124 K/decade; the Middle-lower Yangtze shows natural vegetation greening related cooling of -0.106 K/decade. Both the intensity of the land surface changes and the temperature sensitivities drive the large spatial variability of the temperature effect. Overall, the temperature effects of surface changes are spatially heterogeneous and show considerable magnitudes. We emphasize that vegetation changes in eastern China show a strong surface cooling effect, and may contribute to the regional climate mitigation in the context of global warming.