Tuesday, 14 May 2002: 8:30 AM
Teleconnection impacts on regional daily precipitation modeling
El Nino-Southern Oscillation is known to have significant impact on United States hydroclimatology. The warm and cool phases of ENSO, El Nino and La Nina respectively, tend to have opposite effects in certain regions of the western US. These effects are also in opposition between the Pacific Northwest and the Southwest US. A stochastic daily precipitation model is used to study the impact of ENSO on model parameters and model output. The Southern Oscillation Index, as a surrogate for ENSO, is used to "perturb" the parameters of a daily precipitation model for both the occurrence process and daily amount. Maximum likelihood is used to identify optimal model parameters for unperturbed and perturbed cases. Seasonal precipitation amounts simulated by the two cases are compared to each other and to observed precipitation. Examples of seasonal precipitation simulations conditioned on historic SOI are presented as an application of this technique. Extensions to other US regions and teleconnections will be discussed.