A TOA Spectral Reflectance Model of Railroad Valley Playa Site to Compensate the Missing RadCalNet Data

The spectral reflectance data and the atmospheric parameters released by Radiometric Calibration Network (RadCalNet) have been widely used in many works and application fields. Unfortunately, due to many unexpected factors, the spectral reflectance data are missing, which will seriously influence the application level and usage domain of RadCalNet data. Therefore, how to compensate the missing RadCalNet data is extremely urgent to be solved. Taking Railroad Valley Playa site as the investigated site, a top-of-atmosphere (TOA) spectral reflectance model is proposed to simulate the missing RadCalNet data with high accuracy. The preliminary simulated TOA spectral reflectance is derived and validated. Compared to the real TOA spectral reflectance of RadCalNet data, it is found that the preliminary simulation accuracy is lower, of which the root-mean-square errors (RMSEs) are up to 3.31%. After analyzing the consistency of the time-series TOA reflectance measured by Landsat8 Operational Land Imager (OLI) and the corresponding equivalent TOA reflectance of RadCalNet data in five OLI bands, it is encouraging that the RMSEs of relative differences are less than 1.82%. Thus, the scale factors of these two TOA reflectances in five OLI bands are interpolated to obtain the corresponding scale factors of 61 bands in the spectral range from 400 to 1000 nm with 10-nm intervals to correct the preliminary simulated TOA spectral reflectance. The validation results show that the accuracies of the corrected simulation results are significantly improved, of which the RMSEs are all less than 1.85%, which can be used to effectively compensate the missing RadCalNet data. In addition, the influences of the input parameters, interpolation method, and geopositioning error of OLI on the simulation accuracy are sufficiently discussed to further reveal the probable effect factors of the proposed method.