Establishing Proximal Causes Of Soil Moisture Deficits Accompanying Great Plains Drought Development.
Livneh, Ben 1 ; Hoerling, Martin P 2
1 University of Colorado, Boulder
2 National Oceanic and Atmospheric Administration
The occurrence of drought is associated with far reaching socio-economic impacts, and thus there is great interest in improving its predictability. In this work we focus on the physical relationships between antecedent soil moisture and drought occurrence for the Central Great Plains region. The analysis is centered around the May through August (MJJA) season given its importance as both the agricultural growing season, as well as representing the climatological rainy season. In the first part of the analysis, the historic drought of 2012 is simulated with two hydrologically-based land surface models, driven by observed meteorology and compared with two independent drought estimates. A synthetic experiment to quantify the importance of meteorological drivers is presented in which precipitation and temperature are set to their respective climatological values. In the second part, ongoing research into the relationship between meteorological drivers and antecedent moisture are presented through an ensemble of 35-year GCM simulations (1979-2013) forced by observed oceanic and radiative conditions; resulting in more than 1000 unique sample years. The spread among the top 1% most severe model droughts will be used to understand how the range of antecedent moisture and meteorological conditions affect the trajectory of soil moisture throughout the growing season. Inferences will be made as to whether antecedent conditions can provide a reliable estimator of seasonal drought behavior.