Validation of a Drought Index Based on Smos Soil Moisture Product Over An Agricultural Area in Central Mexico

Satellite remote sensing provides information on near-surface soil moisture at a global scale, thus allowing for a broad range of studies, such as, the forecasting and monitoring of drought. Accurate knowledge of soil moisture (SM) is crucial in hydrology, micrometeorology, and agriculture, as it allows for the estimation of energy and moisture fluxes within the land surface. In accordance with the National Aeronautics and Space Administration, during April of 2021, 85% of the Mexican territory was affected by drought. In Mexico, the main tool for monitoring drought is the Drought Monitoring in Mexico, which uses an intensity scale to describe the intensity of drought within a given region. The scale is defined as follows: the level (D0) abnormally dry, (D1) moderate drought, (D2) severe drought, (D3) extreme drought, and (D4) exceptional drought. Domestic corn production for self-consumption and the agroindustry in Mexico are under threat because of the effects caused by the increase of droughts in terms of frequency, duration, and intensity. For instance, in 2020, corn production in the central state of Tlaxcala dropped by 40%, due to a long drought period from April to August. The local agricultural drought is an important condition to monitor, therefore, the European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) satellite was launched in 2009. This satellite has shown its potential in different applications, for instance, the calculation of indices to determine the vegetation's health that can also be used as drought indicators. In this paper, we present a Soil Water Deficit Index (SWDI) from the data obtained on the THEX-MEX'18 experiment.