*3.5. Validation*

We used the time series field-observed local noon albedos at FluxNet sites to validate the albedos estimated with the EnKF algorithm. Spatially continuous albedos derived by the direct estimation approach were selected to validate the accuracy of estimated albedo at the regional scale. Single-point verification was performed at 15 FluxNet sites as shown in Table 1; the spatial representativeness of each FluxNet site was investigated according to the method described in Section 3.1. Three statistical parameters, coefficient of determination (R2), RMSE and Bias, were used to evaluate the results. If the maximum error between the estimated result and the validated value did not exceed 0.05, the estimated result was considered accurate enough for scientific use [1,53].
