Land Surface Albedo Retrieval in the Visible Band in Hefei, China, Based on BRDF Archetypes Using FY-2G Satellite Data  
[PERSON]  
1 Laboratory of Photoelectric Detection, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; [EMAIL_ADDRESS] (L.H.)  
[PERSON]  
1 Laboratory of Photoelectric Detection, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; [EMAIL_ADDRESS] (L.H.)  
[PERSON]  
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[PERSON]  
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[PERSON]  
1 Laboratory of Photoelectric Detection, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China; [EMAIL_ADDRESS] (L.H.)  
[PERSON]  
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[PERSON]  
4 Laboratory of Atmospheric Optics, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China  
45 Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230031, China  
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[PERSON]  
4 Laboratory of Atmospheric Optics, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China  
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certain requirements for the amount of observation data and the distribution of observation angles [16; 17; 18]. For example, the amount of observation data is required to be greater than or equal to seven points, and the range of observation angles is as large as possible. In addition, the limitations of satellite sensor sampling capability and the influence of weather limit the inversion accuracy [19]. Although the Fengyun geostationary meteorological satellite observes the Earth once every hour [20], which meets the requirements for the quantity of surface albedo observation data, the observation angle of the geostationary meteorological satellite for a specific area is relatively fixed, and the distribution range changes little, thus limiting the application of inversion of land surface albedo using a kernel-driven model.  
Assuming that the same type of region has similar BRDF shapes, [PERSON] and [PERSON] [18] proposed fitting the a priori shape to the BRDF shape that is optimal for the observation data to improve the inversion accuracy. [PERSON] et al. [21; 22] proposed using the anisotropic flat index (AFX) and multiangle observation datasets to build a BRDF archetype database and used the BRDF archetype as a priori knowledge to extract albedo. [PERSON] et al. [19; 23] showed that when the view zenith angle is less than 40\({}^{\circ}\), the relative accuracy of this method is improved by 5%\(\sim\)10% compared with the MODIS full-inversion algorithm. In addition, the introduction of BRDF archetypes can improve the overall classification accuracy by approximately 5% [24; 25]. [PERSON] et al. [26] used the AFX and the albedo-to-nadir reflectance ratio (AN ratio) as prior knowledge and combined MODIS BRDF for high temporal-spatial resolution Landsat-8 albedo inversion. [PERSON] et al. [27] combined both the AFX and the perpendicular anisotropic flat index (PAFX) to build a 3-by-3 matrix of BRDF archetypes for albedo inversion. In summary, the AFX-based BRDF archetype inversion method provides a good way to solve the albedo inversion problem mentioned above.  
The main purpose of this study is to introduce a new inversion method to solve the problem of fixed observation angles when retrieving land surface albedo from Fengyun-2G (FY-2G) geostationary satellites to realize the rapid retrieval of daily land surface albedo in Hefei, Anhui, China. This study serves to model the environmental radiation field in Hefei, Anhui, and provide effective surface input parameter support. Second, aiming at the surface reflection characteristics of the Hefei area, the BRDF archetype of this area is extracted instead of applying the global-scale BRDF archetype, which makes the prior knowledge of BRDF more targeted. Finally, this research contributes to improving the utilization rate of Fengyun geostationary satellite data.