Abstract Author: Renguang Wu and James L. Kinter III
Abstract Title: Relationship of U.S. droughts with SST and soil moisture: Distinguishing the time scale of droughts
Abstract: The impacts of droughts depend on the time scale of droughts and the reasons for short-term and long-term droughts may be different. The present study distinguishes the time scale of droughts based on the standardized precipitation index and analyzes the relationship between sea surface temperature (SST) and soil moisture and boreal summer U.S. droughts. It is found that the relative roles of remote SST forcing and local soil moisture differ significantly for long-term and short-term droughts in the U.S. Great Plains and Southwest. For short-term droughts (<= 3 months), simultaneous remote SST forcing plays an important role. For medium-term and long-term droughts (>= 6 months), preceding remote SST forcing contributes to droughts through soil moisture and evaporation changes. A dominant remote forcing for U.S. droughts is tropical Pacific SST. The most notable impacts of the tropical Pacific SST are found in the Southwest with extension to the Great Plains. Tropical Indian Ocean SST forcing has notable influence on medium-term and long-term droughts. The relationship between tropical Indian and Pacific Ocean SST and boreal summer U.S. droughts show obvious long-term changes especially for the Great Plains droughts.