| Surface net radiation (SNR) is the main factor which affects the energy exchange between the earth surface and near-surface atmosphere, as well as the heat balance. The SNR mainly depend on the surface albedo, the surface temperature, and the emissivity. It brings great impact on the distribution differences which often lead to spatio-tempro change of the natural phenomena. Generally, the surface net radiation can be expressed as the sum of the net short-wave radiation and the net long-wave radiation, as well as the difference between the upward and downward radiation. The calculation of SNR usually requires large amounts of field observation data, and for small scale of observation, it may be set up by several data acquisitions. But for a large scale of surface net radiation balance research, it is difficult to implement the method, which is extravagant and time consuming.Using remote sensing technology to perform the inversion of surface net radiation, making full use of its wide-ranging data acquisition capacity and short-time repeating observation ability, we can greatly reduce the time needed for data acquisition and updating. The purpose of this article is to combine remote sensing products and ground-based observations to perform the inversion of the SNR in2010. Then, the accuracy of the inversion result was assessed. Based on this, the author explored the influence that the surface parameters had on the SNR, and the change characteristics of the surface parameters in the different landcover types.First of all, according to surface net radiation parameterization scheme, this acticle has estimated the surface net radiation and evaluated precision of inversion results, based on the GLASS products (8-days surface albedo, daily downward short-wave radiation,8-days surface emissivity), the MODIS products (land surface temperature and land cover), and ground-based observations (air temperature, relative humidity, daily maximum net radiation) in2010. Then, we simply discussd the response of surface radiation balance to the changes of surface albedo and surface emissivity. Finally, we reclassified the land cover product according to land cover types, and implemented the statistics and analysis of the annual changes of different surface types based on the inversion datas of surface parameters.Results show that:(1) the method is capable of estimating the daily maximum surface net radiation according to radiation balance function, based on the GLASS datas, the MODIS datas and the ground-based observations. The inversion results show good agreement with the ground-based observations, prominently at the level of p<0.05, and the correlation coefficient and estimation efficiency is above0.8and70%, and the maximum RMSE is about40w·m-2.(2)Generally, the net radiation gradually reduce from southwest to northeast in China,2010, similarly to the change trend of short-wave net radiation. While, the long-wave net radiation is nagetive and plays an important role in regulating the radiatioin balance.(3)The daily net radiation is mainly affected by albedo and surface emissivity, and the effect of albedo is bigger than the latter.(4)The surface parameter is accompanied by the change of the underlying, which can be tested effectively by the reclassified results of land cover data in IGBP classification system. Additionally, the change feature of each type is remarkable. According to the comparation of land surface parameters annual change among all the land cover types, the change is seasonly and relates to temperature and status of vegetation. According to the transfer matrix, the net radiation of the land with covers is higher than bare area, and the climate and land surface radiation balance will be broken if the vegetation type is destroyed. |
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