黄土高原区域气候暖干化对地表能量交换特征的影响

本文将观测试验资料与陆面过程模式模拟资料相结合, 对目前4个流行的陆面过程模式的模拟资料进行了验证分析, 发现通用陆面模式(CLM)模式的模拟资料在黄土高原地区比较可靠. 在此基础上,利用近几十年CLM模式模拟资料和气象站观测资料, 分析了黄土高原地区的区域气候和地表能量交换特征的变化规律, 研究了该地区地表能量交换对降水和温度变化的响应特征, 讨论了该地区气候变化对地表能量交换特征的影响机理. 研究发现,近几十年来黄土高原区域气候表现为明显的暖干化趋势, 从而引起太阳总辐射、地表反射辐射和地表长波向上辐射的增加 及地表长波向下辐射的减小,并由此造成地表净辐射通量减少. 与之相对应,不仅地表潜热通量呈减小趋势,而且地表感热通量和土壤热通量也呈减小趋势, 但地表热量分量的分配比例基本不变.并且发现,地表感热通量的年变化主要由太阳辐射控制, 而潜热通量的年变化则受太阳辐射和降水共同影响;地表热量分量的年际变化均对降水变化响应很敏感, 而对温度变化响应不太敏感,气候干旱化对地表能量平衡的影响比气温变暖的影响更突出. 关键词： 黄土高原 区域气候暖干化 陆面过程模拟 陆面能量交换

Warming and drying climate over Loess plateau area in China and its effect on land surface energy exchange

China's Loess plateau, as one of the areas in the world, is vulnerable to ecological environment and sensitive to climate change. The characteristic of land surface process has been changing in this area, and it affects the formation and evolution of regional weather and climate. However, limited by observational land surface data, exchange process variation of the surface energy of the Loess plateau and its mechanism of response to climate change is limited. In this study, we combine the observed experimental data with the land surface model simulated data, test the previous four land surface models. It shows the CLM is reliable in Loess plateau. Then we use the observed data and model simulated data to analyze the variation of regional climate and the characteristics of land surface energy exchange, and discuss the effect of climate change on land surface energy exchange. It shows that Loess plateau is warming and drying in recent decades. It induces the increase in solar radiation, surface reflected radiation and surface longwave upward radiation. This makes the net radiation decrease. Correspondingly, surface latent heat flux, sensible heat flux and soil heat flux all have a decreasing trend. But the distribution ratio of components of surface heat flux is basically unchanged. In addition, the annual variation of sensible heat flux is controlled by solar radiation, and latent heat flux is controlled by solar radiation and precipitation. The annual variation of each component of surface heat flux is sensitive to precipitation, not sensitive to temperature. The climate acidification affected surface energy balance farmore than temperature rise.
Keywords： Loess Plateau regional climate warming and drying land process simulation land surface energy exchange