Characteristics of land surface thermal-hydrologic processes for different regions over North China during prevailing summer monsoon period

Abstract

The observation stations of Northern China are divided into three regions: the arid Northwest China, the Loess Plateau, and the cool Northeast China. The consistencies, differences, and associated mechanisms of land surface thermal-hydrologic processes among the three regions were studied based on the normalization of major variables of land surface thermal-hydrologic processes, using data collected during prevailing summer monsoon period (July and August, 2008). It is shown that differences of surface thermal-hydrologic processes are remarkable among the three regions because of different impacts of summer monsoon. Especially their soil wet layers occur at different depths, and the average albedo and its diurnal variations are distinctly different. Surface net short-wave radiation in the Loess Plateau is close to that in the cool Northeast China, but its surface net long-wave radiation is close to that in the arid Northwest China. And the ratio of net radiation to global solar radiation in the cool Northeast China is higher than the other two regions, though its temperature is lower. There are obvious regional differences in the ratios of surface sensible and latent heat fluxes to net radiation for the three regions because of distinct contribution of sensible and latent heat fluxesto land surface energy balance. The three regions are markedly different in the ratio of water vapor flux to pan evaporation, but they are consistent in the ratio of water vapor flux to precipitation. These results not only indicate different influences of climate and environmental factors on land surface thermal-hydrologic processes in the three regions, but also show that summer monsoon is important in the formation and variation of the pattern of land surface thermal-hydrologic processes.