SCIENCE OF SEASONAL CLIMATE PREDICTION

Predictability limits for seasonal climate variability: Methodologies and current estimates
by Arun Kumar, Climate Prediction Center, National Centers for Environmental Prediction, US National Oceanic and Atmospheric Administration

Dr Arun Kumar graduated from Department of Meteorology, Florida State University, Tallahassee, Florida in 1990, and since his graduation has been affiliated with the National Centers for Environmental Prediction (NCEP). He is currently the Deputy Director of the Climate Prediction Center (CPC) at the NCEP. His research interests include understanding and assessment of seasonal climate predictability; development of application models for seasonal predictions; analysis of lowfrequency trends; ENSO variability and predictions; multi-model ensembles etc. He has authored and co-authored more then 60 papers in peer reviewed journals.

Predictability limits for seasonal atmospheric climate variability depend on the fraction of seasonal variance that is due to factors external to the atmosphere (eg. boundary conditions) and the fraction that is internal. Decomposition of observed seasonal variance into predictable (or external) and unpredictable (or internal) components, however, remains an outstanding (and often a controversial) issue. The importance of this decomposition is highlighted by the fact that the average skill of seasonal prediction has a fundamental limit that is determined by the ratio of external-to-internal variance.

In this talk reasons why limits to seasonal predictability should exist will be briefly discussed. Procedures for estimating atmospheric internal variability will be also outlined, and current estimates of seasonal predictability for surface temperature and rainfall over Australia will be presented.