SMAP Soil Moisture Change as an Indicator of Drought Conditions

Authors

Rajasekaran Eswar, California Institute of TechnologyFollow
Narendra N. Das, California Institute of TechnologyFollow
Calvin Christian Poulsen, University of Nebraska-LincolnFollow
Ali Behrangi, California Institute of Technology & University of ArizonaFollow
John Swigart, University of Nebraska-LincolnFollow
Mark D. Svoboda, National Drought Mitigation Center/University of Nebraska-LincolnFollow
Dara Entekhabi, Massachusetts Institute of TechnologyFollow
Simon Yueh, California Institute of TechnologyFollow
Bradley Doorn, Science Mission DirectorateFollow
Jared Entin, Science Mission DirectorateFollow

ORCID IDs

https://orcid.org/0000-0001-6227-4873

Date of this Version

5-19-2018

Citation

2018 by the authors

Comments

Remote Sens. 2018, 10, 788; doi:10.3390/rs10050788 www.mdpi.com/journal/remotesensing

Abstract

Soil moisture is considered a key variable in drought analysis. The soil moisture dynamics given by the change in soil moisture between two time periods can provide information on the intensification or improvement of drought conditions. The aim of this work is to analyze how the soil moisture dynamics respond to changes in drought conditions over multiple time intervals. The change in soil moisture estimated from the Soil Moisture Active Passive (SMAP) satellite observations was compared with the United States Drought Monitor (USDM) and the Standardized Precipitation Index (SPI) over the contiguous United States (CONUS). The results indicated that the soil moisture change over 13-week and 26-week intervals is able to capture the changes in drought intensity levels in the USDM, and the change over a four-week interval correlated well with the one-month SPI values. This suggested that a short-term negative soil moisture change may indicate a lack of precipitation, whereas a persistent long-term negative soil moisture change may indicate severe drought conditions. The results further indicate that the inclusion of soil moisture change will add more value to the existing drought-monitoring products.