We examine the dynamics of intraseasonal, interannual, and decadal variability in Southwest U. S. rainfall patterns utilizing wavelet analysis (WT) to describe the spatial-temporal behavior of precipitation. WT applied to time series allows not only detection of the periodic fluctuation in frequency space, but also their temporal localization.

We analyze daily precipitation data from station and reanalysis data for the years 1900-2001 for regions of Arizona/New Mexico (AZ/NM) in order to identify dominant modes of variability of precipitation and coherence with large-scale circulation. Preliminary analyses of annual time series reveal that summer rainfall in the AZ/NM is modulated by large-scale, low-frequency (20-50 day) dynamics. Improved understanding of these interactions could lead to more accurate seasonal forecasting of precipitation, important for management of Western U. S. water resources and for GCM evaluation in climate change studies.

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Tennent, W. J. and B. Hewitson. 2002. Intraseasonal rainfall characteristics and their importance to the seasonal prediction problem. Int. J. Climatol. 22; 1033-1048.

Torrence and Compo. 1998. A practical guide to wavelet analysis. Bull. Amer.Met Soc., 79, (1), 61-78.