J12.13
A Synoptic Model of Low Frequency Variability with Application to Subseasonal Prediction
Klaus M. Weickmann, NOAA/ERL/CDC, Boulder, CO; and E. Berry
Subseasonal monitoring and forecasting must consider effects from multiple time/space scale interactions. Weather prediction models include such interactions, but model error and initial condition errors preclude an exclusive dependence on them.
A synoptic model consisting of three time scales is proposed and is applied to the 2001-02 (DJF) winter period. The three time scales are a 30-70 day quasi-osicllation that primarily represents the Madden-Julian oscillation, a 10-60 day band that represents midlatitude interactions such as teleconnection patterns and zonal index cycle variations (~5-10 day decorrelation time scale), and a less than 10 day band to represent storms and baroclinic wave packets (~1-2 day decorrelation time). The latter spread information around the northern hemisphere in less than 10 days. A unique feature of the model is its focus on transitions and extreme events. Tropical-extratropical interaction during the January 30-31, 2002 ice storm over the U.S. central Plains will be described. The atmospheric angular momentum budget provides a useful quantitative monitoring framework for the synoptic model, including the role of mountains and surface zonal wind stresses.
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Joint Session 12, Subseasonal forecasting (Joint with 15th Symp. on Global Change and Climate Variations and the Symp on Forecasting the Weathe and Climate of the Atmosphere and Ocean; Room 6C)
Tuesday, 13 January 2004, 8:30 AM-5:30 PM, Room 6C
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