黑河流域植被覆盖度计算及其影响的中尺度模拟

运用基于遥感的中国西北土地覆盖动态监测系统(NOAA AVHRR Processing Chain,NOAA-Chain)预处理系统对改进的甚高分辨率扫描辐射仪(AVHRR)影像资料进行处理得到的归一化植被指数(NDVI),基于像元二分原理得到2002年黑河流域植被覆盖度分布,将其与Gutman 1998年所作全球植被覆盖度数据在黑河流域范围进行了对比分析,发现2002年黑河流域中上游植被整体呈退化趋势,主要绿洲区植被覆盖度增大。分别将这两套植被覆盖度数据引入中尺度大气模式MM5中进行黑河流域中上游气候模拟。通过与气温观测值的比较,发现用黑河流域植被覆盖度数据模拟的气温偏差小于用全球植被覆盖度的模拟结果;植被分布与潜热通量分布的空间相关性最好;植被覆盖度变化对局地温度场变化影响很大。

Vegetation Coverage Fraction Calculation and the Mesoscale Modeling in Heihe River Basin

Monthly vegetation coverage fraction data were obtained by dimidiate pixel model.The normalized difference vegetation index(NDVI) derived from NOAA-CHAIN preprocess system was used.It was compared with global vegetation coverage data developed by Gutman in 1998,in the upper and middle reaches of the Heihe river basin,it is found that vegetation degraded in 2002 compared to the end of 1980's,it is same as conclusion from monitoring of Northwest China land cover.These two sets of vegetation coverage fraction data were used in atmospheric mesoscale model MM5,specifically.The conclusion is that the bias between simulated air temperature from Heihe vegetation coverage fraction and observation is smaller than using climatic vegetation coverage fraction.The spatial correlation coefficient is the highest between vegetation coverage fraction distribution and latent heat flux distribution.While,as for the spatial correlation coefficient between vegetation coverage fraction change and soil/atmosphere element change fields,2 m temperature is the highest.