基于CLM模型的植被覆盖变化对黄土高原气温和降水的影响研究

Vegetation Cover Change Effects on Climate in the Loess Plateau Region Based on CLM Model

黄土高原位于我国第二阶梯,地理环境复杂,生态环境脆弱。本文结合GIMMS/NDVI遥感数据与气象站点观测资料开展诊断分析研究,并将其与模型模拟试验相结合,通过这种方法来研究黄土高原地区植被覆盖与气温和降水之间的作用关系。研究结果表明,黄土高原地区的NDVI、气温和降水量均具有明显的季节变化特征;1982—2006年,区域滑动平均NDVI、气温和降水的线性变化斜率分别为5E-04/10a、0.061℃/10a和-0.492mm/10a;研究区域内NDVI与气温和降水的同期滑动平均相关系数分别为0.459和-0.23,且均存在较明显的空间差异。应用CLM陆面过程模型的模拟结果表明,植被覆盖增加后,植被覆盖发生变化地区的净短波辐射有所增加,净长波辐射有所减少,导致地表吸收净辐射有增加趋势;研究区域内的感热通量和潜热通量均有所增加,且潜热通量的增加更为明显,这可能对植被覆盖增加后气温的降低产生一定影响;研究区域内的土壤含水量和地表蒸散均呈增加变化,这可能导致降水增加。但是,植被覆盖增加对区域气温降低和降水增加的影响作用有限。

Loess Plateau region locates in the second step of China with a complex geographical environment and fragile ecological environment. This paper aims to investigate the relationships between vegetation cover and climate in Loess Plateau region by diagnostic analysis and numerical simulation tests with GIMMS NDVI and stationary observed datasets. The results combining with diagnostic methods has shown that NDVI, temperature and precipitation of Loess Plateau region exhibit obvious seasonal variation characteristics; In 1982-2006, the regional slope of average NDVI , temperature and precipitation is 5E-04/10a、0.061℃/10a and -0.492mm/10a, and the moving average correlation coefficient of NDVI＆ temperature and NDVI＆ precipitation in the same period is 0.459 and -0.23, it shows that vegetation cover is closely related to the climate, with a positive （negative） correlation with temperature （precipitation）, and with obvious spatial difference. By using the simulation of CLM, we discuss the effects on land atmosphere interaction whenever the vegetation cover has changed. When the vegetation coverage increases, the surface net radiation absorption of the vegetation cover change area performs a increasing trend，regional annual average surface net radiation absorption increase 1.18 W/㎡; The regional annual average sensible heat flux has increased0.97 W/㎡, latent heat flux has increased 0.54 W/㎡, atmospheric water content has decreased 1.51E-05 kg/kg, This affects the temperature and precipitation to a certain extent.