92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 9:00 AM
Comparison of Coupled and Uncoupled WRF-ROMS Simulations of Eight Nor'easter Cases
Room 340 and 341 (New Orleans Convention Center )
Stephen D. Nicholls, Rutgers University, New Brunswick, NJ; and S. G. Decker

Weather Research and Forecasting (WRF) model handling of the ocean remains far more primitive compared to the atmosphere. As of WRF 3.2, three options exist for addressing the sea surface temperatures (SSTs): Static, external model input, and a 1-D mixed-layer model. Out of these options, only the latter considers a two-way interaction between the atmosphere and ocean, but it is only for one domain and neglects advection. Coders of WRF have in large part neglected the ocean arguing that its much longer time-scale does not justify the computational cost. Such reasoning, however, does not consider tropical cyclones or nor'easters, which can induce rapid large-scale upwelling and cooling upwards of 5K on a time scale of less than 84 hours. Such cooling is especially problematic for accurate nor'easter simulations given the baroclinic nature of these systems. For this study, we utilize a recently developed WRF-Regional Ocean Modeling System (ROMS) model to observe how the inclusion of a dynamic ocean affects eight nor'easter simulations. Specifically, this study compares the performance of the coupled and uncoupled model systems and determines how the changed heat and moisture fluxes alter the WRF simulation of each nor'easter event. The simulations are then compared to a “ground truth” dataset. Additionally, we illustrate how the cyclogenesis, storm track, and microphysical properties of each simulated nor'easter are impacted.

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