Improvement Of Albedo Retrieval In China By Satellite Remote Sensing

The land surface albedo is an important surface parameter in the climate and land surface process model. Due to the influence of cloud cover and poor quality data, the inversion efficiency and inversion accuracy of surface albedo in China are greatly reduced. A comprehensive understanding of the temporal and spatial distribution characteristics of MODIS albedo retrieval quality in China would not only helps to promote the application of this product in China's climate and land surface process model and numerical weather forecast, but also provides a reference for the study of satellite remote sensing inversion of surface albedo in China.The surface channel setting of Suomi NPP / VIIRS is basically the same as that of EOS / MODIS. Both the orbit parameters and the Observation data's processing plan of the two detectors are completely different. Therefore, combining both observations can obtain sufficient multi-angle clear sky observation data in a short period of time to improve the temporal and spatial distribution continuity and inversion accuracy of surface albedo in China.The main work of this paper includes:(1) Analysis on distribution of MODIS albedo inversion in China. Using MODIS albedo retrieval quality data MCD43A2,the spatial and temporal distribution characteristics of surface albedo retrieval quality over China during 2003 to 2015 is statistically analyzed in the paper. The results are as following: there was observably difference in the spatial distribution of MODIS surface albedo retrieval quality in China. Albedo retrievals with the best quality of full inversion mainly distribute in North China, Northeast China, Northwest China, and Midwest region of Southwest China. In spring, summer and fall, only Northeast China, North China and Northwest China have more than 60% of the area can be obtained with high accuracy MODIS surface albedo to meet climate and land-surface model accuracy requirement; Only 40%-60% of the area in Southwest China and less than 20% of the area in East China,Central China and Southern China can be obtained with high accuracy MODIS surface albedo to meet climate and land-surface model accuracy requirement throughout the year.(2) Spectral correction of VIIRS and MODIS inversions. This chapter firstly uses 6S to combine VIIRS detector SRF and MODIS detector SRF respectively to carry out radiation transmission simulation to obtain the clear sky surface reflectivity data sets in various typical surface and atmospheric radiation conditions. Then, based on the statistical fitting, we obtain the spectral conversion equation between VIIRS and MODIS reflectance in China. Finally, the conversion equation is used to realize the spectral correction of the two observations.(3) The improvement of albedo inversion method by combining VIIRS and MODIS observations. Albedo is inversed with reflectance observed by MODIS and converted from VIIRS with the spectral conversion equation. In this paper, 3 group comparison inversion experiments are set up. Finally, MODIS albedo products were used to verify the results of joint inversion. The results show that: not only the continuity of the spatial distribution and the inversion accuracy of the inversions can be improved, but also the inversion period can be shorten.