Climate Observations and Services
Weather-Climate Connection
What is requested?
As part of the FY2002 request for Climate Observations and Services in the Oceanic and Atmospheric Research budget activity, NOAA is requesting $0.9M to examine how short-term changes in the Pacific Ocean and the overlying atmosphere can affect the development of storms approaching the United States. This represents one of the most promising ways to improve the predictions of intense storms, droughts, and floods. Exploiting the connection between the climate variability of El Niño and the weather over the United States is one of the areas of research most likely to provide tangible improvements in weather forecasting.
Why do we need it?
During El Niño, shifts in the Pacific storm track affect the paths of storms approaching the U.S. west coast and influence weather across the entire country. Other tropical fluctuations on weekly to monthly time scales can lead to similar effects on U.S. weather. Further, the effects of tropical variations are not confined to El Niño years and may indeed be even more important when direct El Niño-Southern Oscillation effects are weak. These relatively fast tropical-mid latitude interactions provide a potentially important additional source of information for advanced weather forecasting beyond simple predictions of El Niño. Emerging evidence suggests that these rapid surface wind variations over the tropical Pacific and Indian Oceans also substantially influence the initiation, evolution, and termination of El Niño events, and thereby directly affect how well El Niño can be predicted.
What will we do?
At present, operational forecast models do not simulate these week-to-week tropical fluctuations well, if at all. It is likely that both atmospheric and oceanic conditions are important in determining how these disturbances change with time. However, current forecast models typically do not allow for the ocean-atmosphere feedbacks that can substantially influence tropical variability operating at 30-to-60 day time scales. NOAA will expand its diagnostic and modeling efforts to understand the relationship between sub-seasonal tropical variability and changes in the frequency, location, and intensity of extreme weather events over the U.S., and document the structure of variations in tropical rainfall on weekly to monthly time-scales, as well as air-sea interactions in both tropical systems and in mid-latitude oceanic and land-falling storms. Observational and modeling efforts will aim to document the pattern of variations in tropical rainfall on weekly-to-monthly time scales as well as air-sea interactions both in tropical systems and in mid-latitude storms.
What are the benefits?
Advanced predictions of extreme events such as droughts and floods are products most frequently cited as critical needs by users of climate information. Benefits of establishing the link between climate and extreme weather events include improved operational climate forecasts and more effective risk and resources management. During the 1997-98 El Niño event, NOAA researchers demonstrated the high value of establishing rapid transfer of research data and information to forecast offices, water resource managers, emergency managers, decision makers, the media, and the public. Improvements in forecasting both climate variability and high impact weather will provide significant economic benefits only if they are communicated effectively to the end-users of the information through a strong regional assessment program.