University of Cincinnati researchers are at work tracking drought patterns across the United States. Qiusheng Wu, a doctoral student and research assistant for the UC Department of Geography, and Hongxing Liu, a UC professor and head of the Department of Geography, will present details this week at the annual meeting of the Association of American Geographers (AAG) in Tampa, Fla.
To trace the dynamics around agricultural drought, the UC researchers implemented an Event-based Spatial-Temporal Data Model (ESTDM) to detect, track and monitor conditions. The framework organizes data into objects, sequences, processes and events.
The data was collected from the European Space Agency's (ESA) Soil Moisture and Ocean Salinity (SMOS) satellite, which was the first of its kind dedicated to measure moisture near the surface of the soil. The study focused on four years of data (2010-2014), which included the devastating Texas drought in 2011 and the 2014 California drought.
The satellite uses an L-band (1.4 Ghz) passive microwave radiometer to analyze the spatial and temporal variations of soil moisture and ocean salinity. "Recent studies have shown that many historical drought events in the U.S. are closely related to La Nia, a phenomenon known for its periodic cooling of sea surface temperatures in the tropical Pacific Ocean. So in addition to measuring soil moisture for drought monitoring, it is also important to measure ocean salinity," explains Wu.
The satellite can penetrate the Earth's surface up to 5 centimeters, providing a soil variable for each pixel, which represents 25 kilometers. The satellite's data collection occurred over a three-day rotation.
The researchers were examining patterns of spreading drought to develop predictions for future drought events.
"Soil moisture is defined as the ratio between volume of water and volume of soil holding the water, which is expressed in percentages, so high soil
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University of Cincinnati