A global passive microwave based wetness index for the monitoring of soil moisture and inundation

Abstract

The objective of study is to implement an automated microwave based index to detect and monitor extreme soil wetness and flooding conditions on global scale. The proposed index is based on the Polarization Ratio (PR) that is determined from brightness temperature measures from the AMSR-E sensor. The Robust Satellite Technique (RST) is then applied to the PR to determine a Polarization Ratio Variational Index (PRVI) which is sensitive to extreme hydrological conditions in term of wetness but also drought conditions. The PRVI was determined at different frequencies ranging from the 37 GHz to the 6.9 GHz. The index was tested during extreme flooding events in Asia and Europe as well as in Northern America. The index was implemented globally using observation from passive microwave instruments. The analysis of the results on global scale shows that the index was sensitive to extreme hydrological event and that false alarms were mostly issued over northern snow covered regions only. This implies that the proposed index can be used to assess and delineate flooding conditions

Introducing multisensor satellite radiance-based evaluation for regional Earth System modeling

“…Although there are no in situ observations, the ocean-equivalent level of the dTb depression over land suggests the presence of significant amount of standing water due to temporary flooding from the propagating MCSs Temimi et al, 2012]. Flooded grassland and savanna (around the Sahara-Sahel border) are very common in the tropics and subtropics area over this region.…”

“…At this frequency, TOA microwave radiance is most sensitive to the surface conditions: water/land surface, wetness, soil-vegetation roughness, and terrain structure. AMSR-E has been used for retrieving the land surface soil moisture [Njoku et al, 2003] and flood detection [Temimi et al, 2012]. The emissivity-polarization difference (difference of Tb between vertical and horizontal polarization) of low-frequency microwave Tb is very sensitive to the presence of surface standing water .…”