The initiation and maintenance of extreme hydroclimate events over North America are known to be influenced by the sea surface temperature (SST) forcing over the tropical and subtropical oceans. The remote influences from different basins are governed by different mechanisms, ranging from Rossby wave teleconnection produced by the Eastern Pacific SST to the re-routing of moisture fluxes due to tropical Atlantic SST anomalies. To improve the prediction and the assessment of predictability for North American droughts, the influences from different ocean basins must be integrated into a unified framework. Recent progresses in climate modeling and in the understanding of the influences of the individual basins provide an impetus for a unified investigation of the multi-basin influences on North American droughts using ensemble general circulation model (GCM) simulations. Based on this framework, this study aims to determine quantitatively the combined influences of the SST anomalies in the tropical and subtropical Indo-Pacific Ocean, the tropical and subtropical Atlantic Ocean, the Intra- Americas Sea, and the Near-American Seas on North American droughts, and the mechanisms that facilitate the SST-drought connection on seasonal to decadal time scales. Analyzing ensemble GCM and idealized dynamical model simulations, the proposed work will determine the optimal multi-basin combinations of SST anomaly patterns for producing rainfall anomalies over North America and assess the predictability for North American hydroclimate variability related to specific combinations of multibasin SST anomalies. To accurately attribute predictability to regional SST anomalies, GCMs that are partially coupled to a mixed-layer ocean will be used to quantify the inter-basin interactions among the SST anomalies in the context of SST-drought connection. The dynamical mechanisms, including tropically forced stationary wave, the excitation of zonally symmetric circulation anomalies, and dynamically induced re-routing of moisture fluxes, will be studied using a hierarchy of general circulation and simplified dynamical models. The anticipated new results from this project will contribute to the practical goal of improving the framework of seasonal-to-interannual prediction of North American hydroclimate that utilizes the information from the SST anomalies of all major ocean basins.
|Effective start/end date||7/1/08 → 6/30/13|
- US Department of Commerce (DOC): $140,000.00