I didn't get a perfect agreement between SMAP 36 km (L3_SM_P) and average SMAP-Enhanced 9 km (L3_SM_P_E) radiometric products for each 36 km pixel over my study catchment. I expected a perfect match between these two datasets, since 9km products have been derived from 36 km data.
Can anybody explain the main reasons for these disparities?
Dear Indishe,
I do not think SMAP enhanced 9-km SM product has been derived or downscaled from SMAP 36-km SM product. Backus-Gilbert optimal interpolation techniques are used to extract maximum information from SMAP antenna temperatures and convert them to brightness temperatures, which are posted to the 9 km Equal-Area Scalable Earth Grid, Version 2.0 (EASE-Grid 2.0) in a global cylindrical projection. I am sure you have went through the documents for algorithm used, for example, https://nsidc.org/data/SPL3SMP_E
Therefore, it does not have to have a perfect match. Hope it helps.
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