Sunday, 22 January 2012
An Analysis of WRF Physics Parameterization Scheme Combinations for the January 29 and 30th 2008 Ohio Valley Squall Line Event
Hall E (New Orleans Convention Center )
On January 29th and 30th a squall line of thunderstorms moved through the Ohio valley with over 300 reports of severe weather. As a result, the need for public awareness increases making accurate forecasting of such events important. Modeling is a key component to any forecast. This study examines the performance of several parameterization scheme combinations in the Weather Research and Forecasting Model with regards to this event. These include cloud microphysics (WRF single moment 3 class, 6 class and Goodard), cumulus parameterization (Kain-Fritsch and Bets-Miller-Janjic) and the planetary boundary layer schemes (Yonsei-University and the Mellor-Yamada-Janjic). A total of 12 WRF simulations were conducted for all potential scheme combinations. Data from the WRF simulations for several locations in south central Kentucky was compared to the Kentucky Mesonet observations for 4 locations, Bowling Green, Russellville, Murray and Liberty, KY. A fine model resolution of 1 Km was used over the mesonet locations with courser resolutions of 3 and 9 km used on the outer 2 domains which encompass the Ohio and Tennessee valleys. Also a qualitative analysis between NARR and modeled graphics was investigated using the grid analysis and display system. Overall the most satisfactory scheme combination was the WRF single-moment 3 class Microphysics Scheme, Kain-Fritsch cumulus parameterization scheme and Yonsei University scheme for the planetary boundary layer. However the planetary boundary layer schemes were noted to have the most influence in determination of the most satisfactory model simulations with limited influence from different selections of microphysics and cumulus parameterization schemes.