83rd Annual

Wednesday, 12 February 2003: 4:30 PM
Statistical correction of Central Southwest Asian winter precipition simulations
Michael K. Tippett, Internation Research Institute for Climate Prediction, Palisades, NY; and M. Barlow and B. Lyon
Severe drought is a notable feature of the hydrology of Central Southwest (CSW) Asia. Recent studies have linked the region's interannual precipitation variability to remote forcings that include East Asia Jet Stream variability and Western Pacific Tropical convection. However, atmospheric GCMs have demonstrated little skill in simulating interannual precipitation variability in this region. Here statistical methods of correcting systematic errors in GCM simulations of CSW Asia precipitation are investigated. Canonical correlation analysis is used to identify model fields related to observed precipitation anomaly patterns, and then these correspondences is used to predict observed precipitation anomalies. This approach is applied to the ECHAM 4.5 GCM using regional precipitation, upper-level winds and Western Pacific Tropical precipitation as predictors of observed CSW Asia precipitation anomalies. The statistical corrections improve the GCM precipitation, resulting in modest, but significant and cross-validated, skill in simulating CSW Asia precipitation anomalies.

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