Impact of Land Cover Change on Mountain Circulation over the Hainan Island, China

Abstract

Focusing on the complex underlying surface area in central–southern Hainan Island, this study uses the Advanced Research Weather Research and Forecasting Model (Version 4.0) to simulate a typical mountain circulation case without obvious weather system forcing, and tries to reveal the impacts of land cover changes on the mountain circulation. One control experiment (CNTL) and three sensitivity experiments, in which the current land cover is taken as areas of uniform evergreen broadleaf forest (FOREST), grassland (GRASS), and bare soil (DESERT) coverage, are conducted. The results show that the near-surface wind speed increases with decreasing surface roughness, and DESERT shows the most obvious change as compared with the CNTL. In the vertical direction, FOREST shows the strongest valley breeze circulation, with the largest horizontal and vertical extents of circulation, as well as the highest vertical extent of the updraft. DESERT shows the weakest valley breeze circulation with the longest duration. GRASS shows the slightest change from the CNTL. The possible impact mechanism is that the land cover changes could affect the surface energy partitioning, leading to a variation in the temperature distribution (i.e., the horizontal potential temperature gradient and boundary layer stability), in turn affecting the structure and evolution characteristics of the mountain circulation.