Modeling the effects of the plastic-mulched cropland over the arid and semi-arid areas of China on the East Asian regional climate

Abstract

Arid and semi-arid areas of Northwest China are extremely sensitive to climate change. Plastic mulch is a technology used worldwide to inhibit soil evaporation and increase crop yield. The properties of plastic film are significantly different from the soil. Plastic mulch not only alters the physical attributes of the underlying surface, but also blocks the energy and mass exchanges between the land surface and the atmosphere. This latter situation has not been depicted in current regional climate models. This study couples a detailed plastic mulch layer submodel considering the effects of the plastic mulch on the radiation and heat transfer into the regional climate model RegCM4.5 to explore the effects of plastic mulch on East Asian regional climate over Northwest China. Results suggest that the plastic film covering cropland can enhance the near surface sensible heat transfer, accelerate the rise of near surface air temperature, and reduce the water vapor supply of convective process. Meanwhile, the rainfall is reduced in Northwest China and most areas south of the Yangtze River, while the precipitation is improved from Sichuan and Chongqing to North and Northeast China when the cropland underlying surface is covered by the plastic film. Moreover, the cyclone of the lower troposphere in Northwest China is strengthened and the air pressure is weakened, which promotes the subtropical high to the northwest, thus East Asian summer monsoon is influenced because of the plastic film mulching.