Trends and Variability of Atmospheric Downward Longwave Radiation Over China From 1958 to 2015

Surface downward longwave radiation (SDLR) is a major component of the energy budget. Although studies have reported spatiotemporal variations SDLR in China, coverage situ measurements used always limited. In this study, gradient boosting regression tree (GBRT) was developed to reconstruct based on air temperature (Ta), relative humidity (RH), and shortwave (DSR). Ground collected at Baseline Radiation Network (BSRN) Arid Semi-arid Region Collaborative Observation Project (ASRCOP) were build evaluate GBRT model. The evaluation results showed that daily estimates are correlated well with situ, an overall root mean square errors (RMSE) 16.5 Wm?2 correlation coefficient (R) value 0.91 for validation data set. Comparison existing products accuracy trends method reasonable. To obtain long-term analysis over densely distributed reconstructed DSR ground measured Ta RH 756 Chinese Meteorological Administration (CMA) stations as input estimate China during 1958–2015. estimated SDLRs selected 563 increased average rate 1.3 per decade from 1958 2015. trend positively water vapor pressure, whereas negatively DSR.