Statistical and scaling properties of remotely-sensed soil moisture in two contrasting domains in the North American monsoon region

Characterizing soil moisture (theta) variability is important for inferring high-resolution information from coarse estimates provided by remote sensors. In this study, we analyze the spatial variability and scale invariance of high-resolution theta estimates collected in two contrasting semiarid areas, Arizona (AZ) and Sonora (SON), during the Soil Moisture Experiment - North American Monsoon in 2004 (SMEX04-NAME). Results reveal that as the mean theta condition (<theta >) becomes drier, the spatial standard deviation becomes smaller in both domains. The coefficient of variation of theta decreases with <theta > in SON, but does not display a clear tendency with <theta > in AZ. We also found the presence of scale invariance and multifractality in the range of support scales from 51.2 km to 0.8 km for all soil moisture fields in the two regions. The multifractal properties of theta are clearly linked to <theta > in SON, while the relation is affected by more dispersion in AZ. We argue this is due to differences in the dynamic (rainfall) and static (vegetation) controls on theta in the two domains. (C) 2009 Elsevier Ltd. All rights reserved.