Feng (2018) has estimated GRACE measurement error by obtaining RMS over oceans at the same latitude as the study region. How reliable is the method? Also check: Chen JL, Wilson CR, Tapley BD, Yang ZL, Niu GY (2009b) 2005
drought event in the Amazon River basin as measured by GRACE and estimated by climate models. J Geophys Res 114:B05404. https://doi.org/10.1029/2008jb006056
Is the method reliable? if the method is reliable, should the method be included in the package in a future version?