The B-Parameter Relating L-VOD to Satellite-Scale Crop Plant Water May Not Be Constant Over a Growing Season

Satellite L-band vegetation optical depth (L- VOD) is a relatively new but potentially valuable vegetation product. We hypothesize that the relationship between L- VOD and crop plant water, as characterized by the “b-parameter,” should change over the growing season as crops progress through different developmental stages. We find that the b-parameter derived from SMOS and SMAP L- VOD and satellite-scale estimates of crop plant water made by the Agro-IBIS model does in fact exhibit a growing-season pattern. This pattern is consistent among different years during the first half of the growing season.