1) Understanding North American Drought
While a primary goal is to improve drought prediction, advancing understanding of the mechanisms of drought is critical to advancing modeling capabilities and assessing how the global climate can influence regional conditions. Substantial progress has been made recently to understand the influence of sea surface temperatures (SSTs) in regions far removed from a drought. Nevertheless, some aspects of the influence of global climate conditions on regional drought are still poorly understood, including the impacts of the different ocean basins and the physical mechanisms by which the SST forcing leads to regional hydrological anomalies. These physical mechanisms include changes in atmospheric circulation and moisture transport as well as feedbacks from the land. These processes manifest themselves in large variations in the character of drought (e.g., timing with respect to the annual cycle, frequency, length, intensity, geographical heterogeneity) even with the same large scale forcing. This is indicative of the dependence on the local "background" climatological atmospheric and land conditions as well as the annual cycle.
The focus on three different droughts serves to highlight regional differences and should help ensure that any improvements in modeling capabilities are robust. In addition, by assessing commonalities and differences between the droughts and conducting hindcast and other sensitivity experiments, we will be able to better understand the limits to predictability and the potential for early warning in the different regions.
--- Content provided by Siegfried Schubert, NASA and other DTF PIs ---