Comprehensive Validation and Evaluation of JPSS VIIRS Land Surface Albedo (LSA): Field Measurements Validation, Inter-comparisons, Long-term Monitoring, and Temporal Filtering

Abstract:

Land surface albedo (LSA), part of the Visible Infrared Imaging Radiometer Suite (VIIRS) surface albedo environmental data record (EDR), is an essential variable regulating shortwave energy exchange between the land surface and the atmosphere. Currently, the bright pixel sub-algorithm (BPSA), which estimates LSA directly from VIIRS top-of-atmosphere (TOA) reflectance through simulation of atmospheric radiative transfer, is used to generate LSA products. In order to provide a better assessment of the VIIRS LSA data, this study performed comprehensive validation and evaluation in four aspects: 1) Comparing VIIRS LSA with global field measurements including Surfard, BSRN, GC-net, etc. Result shows VIIRS albedo has an overall bias of 0.004 and root mean square error (RMSE) of 0.024 against those ground sites. 2) Inter-comparing VIIRS LSA with albedo derived from other data source to see the discrepancies of albedo estimation among different sensors. Result shows that VIIRS LSA has a high agreement with high resolution albedo maps derived from Landsat data (bias = 0.003, RMSE = 0.019), and the 16-day mean VIIRS albedo agrees well with MODIS blue-sky albedo (bias = 0.001 and RMSE = 0.019). 3) Establishing a long-term monitoring tool for VIIRS LSA to regularly detect the global albedo change and related disturbances. It provides an important way for investigating global land processes. 4) Developing a temporal filter algorithm to fill gaps on the albedo time series and make it smooth, and more applicable for end users.