Simulative study of the impact of the cropland change on the regional climate over China

The cropland types in the three-period land use and land cover (LULC) data from the remote sensing satellite images were incorporated into the coupled regional climate model AVIM-RIEMS2.0. The NCEP/DOE reanalysis data in the same period was used to drive the AVIM-RIEMS2.0. The research investigated the impact of the cropland change on the regional climate over China. The results show that the impact of cropland change on climate is stronger in summer in contrast with winter over China. The temperature and rainfall difference between the observation and simulation passes the significance test at the 95% confidence level in some areas in the summer. Cropland expansion results from the conversion from woodland or grassland to cropland in the 1980s, with the leaf area index decreasing and surface albedo increasing, both passing the 95% confidence level in the region of vegetation change, leading the temperature to an interval change of "increase-decrease-increase-decrease" from south to north in Eastern China. However, the rainfall changes show a generally opposite trend. The cropland area decreases in the 1990s except for Northeast China. Vegetation changes due to cropland change are opposite to those the 1980s, and the opposite changes also exist in the leaf area index, surface albedo and the climatic variables. The different conversions of vegetation types in the cropland change make the 850 hPa mean wind field appear the general reverse change, which is one of the main reasons leading to the different change of temperature and rainfall.