Session 18.2 Impact of the variations of precipitation particle parameters within the same microphysics scheme in radar data assimilation using EnKF data assimilation technique

Thursday, 20 August 2009: 4:00 PM
The Canyons (Sheraton Salt Lake City Hotel)
Nusrat Yussouf, CIMMS, Norman, OK; and D. J. Stensrud

Presentation PDF (1.7 MB)

Significant uncertainties exist in the precipitation characteristics of storms with the variations of the microphysical parameters within the same microphysics scheme. Several observational studies indicate that the particle densities and intercept parameters of hydrometeor distributions can vary widely within a single storm and among storms. Assuming the same precipitation particle parameters for all precipitation events can lead to significant errors in the analyses and forecasts of severe storms. Therefore, the selection of a microphysics scheme in storm-scale modeling has profound impact on the analyses and forecasts of severe weather events.

In an effort to explore the impact of variations in parameters within the same microphysics scheme, Observing System Simulation Experiments (OSSEs) are conducted using a range of different realizations of the intercept and density parameters using EnKF data assimilation technique. Two sets of experiment are run for each OSSE. One experiment assimilates the simulated WSR-88D Doppler radar observations while the other experiment assimilates the high temporal frequency Phased Array Radar (PAR) observations. Results obtained are then compared to document the value of variations in precipitation particle parameters in the ensemble storm-scale modeling from assimilating radar observations.

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