利用MODIS数据计算中国地表短波净辐射通量的研究

Net Surface Shortwave Radiation Mapping over China Using MODIS Data

地表短波净辐射是辐射能量的重要收入部分,对研究地表辐射平衡、地气能量交换以及各种天气气候的形成都具有决定性的意义。目前国际上利用卫星数据计算地表短波净辐射大多采用空间分辨率较低的宽通道反照率数据(如ERBE卫星数据,空间分辨率为35km),这难以满足局部尺度的能量平衡和蒸散等研究的需要。本文利用空间分辨率达1km的窄通道多光谱MODIS卫星数据,通过相关处理计算,无需气象数据和地面测量数据的参与,就获得了中国的地表短波净辐射通量分布图。经与禹城地区地面实测数据对比可知,晴空时均方根误差小于20 W/m2,有云时均方根误差小于35 W/m2,表明本文使用的地表短波净辐射反演方法适合中国范围地表短波净辐射的计算。

The Net Surface Shortwave Radiation （NSSR） is of important income of the surface radiation. It is crucial to study the surface energy balance, the transportation and exchange of the energy between the Earth＇s surface and its atmosphere, and variously climatic forming and change. The conventional methods, currently, for estimating NSSR depend on broadband satellite data with lower spatial resolution such as Earth Radiation Budget Experiment （ERBE） wide-field-of-view planetary albedo. The spatial resolution of ERBE satellite data having nadir footprints is larger than 30 km, which is difficult to meet the needs of the surface energy balance and the evaportranspiration with regional scales. This paper makes use of the multispectral narrowband data such as Moderate Resolution Imaging Spectroradiometer （MODIS） data with spatial resolution of 1 km, to map the NSSR over china without any inputs of meteorological data and ground measurements. The comparison of the estimated NSSRs with those measured in YuCheng field site shows that the Root Mean Square Error （RMSE） is less than 20 W/m^2 for clear skies and 35 W/m^2 for cloudy skies, which indicates that the method adopted in this paper is feasible to estimate the NSSR of China.