An integrated view of the American Monsoon Systems: observations, models and probabilistic forecasts

Climate Prediction Program for the Americas (CPPA) Science Plan indentified the need to “explore a unified approach to understand the North American (NAMS) and South American (SAMS) monsoons systems, which constitute the two extremes of the annual cycle over the Americas and possible linkages between the two systems.” This proposal will contribute to the CPPA implementation strategy by focusing on the interactions between the two systems and identification of common sources and limits of summer season predictability in the AMS. The main theme of this proposal is to develop a unified view of the AMS. Specifically, it addresses the FY2010 CPPA research priority of Predictability and prediction of intraseasonal to interannual (ISI) climate variations and related impacts over the Americas. The proposal will also evaluate the ability of global models from the World Climate Research Program (WCRP) Coupled Model Intercomparison Project (CMIP) to simulate the variability of the AMS in the present climate.

The project is comprised of four interconnected main goals. First, the project will investigate the extent to which the annual evolution of NAMS and SAMS and their temporal variability on ISI time scales can be represented with metrics that effectively describe changes in precipitation and atmospheric circulation in the Americas. Second, this will identify regional physical processes and teleconnections that control the interactions between NAMS and SAMS. Third, this project will evaluate the skill of WCRP CMIP coupled models in representing the observed variations in the AMS. Lastly, this project will implement diagnostic monitoring tools, identify sources of potential predictability and develop probabilistic forecasts of the AMS on subseasonal to seasonal scales.

Specific objectives are:

I. Develop and validate indices for a unified approach to monitor and forecast the variability of the monsoon systems in the Americas.

II. Investigate the associations between the two monsoon systems, the importance of regional processes and remote atmosphere-ocean variations on ISI time scales in explaining these linkages.

III. Examine the degree to which simulations from the WCRP Coupled Model Intercomparison Project (CMIP-3 and CMIP-5) realistically represent the AMS and associations between the monsoons in the Americas.

IV. Use NCEP Climate Forecast System (CFS) model outputs (reforecasts and operational) to develop probabilistic forecasts of the American Monsoon Systems on subseasonal to seasonal lead times. Identify potential predictability sources of the AMS on ISI time scales.