Extended Abstract (272K)9D.2
Initialization of a hurricane vortex based on single-doppler radar observations
Jim-Luen Lee, NOAA/FSL, Boulder, CO; and A. E. MacDonald, Y. -. H. Kuo, W. -. C. Lee, W. Wang, and S. -. H. Chen
An initialization scheme for tropical storms has been developed and used to initialize hurricane Danny (1997) for a high resolution numerical simulation with MM5/WRF mesoscale models. The newly developed initialization scheme utilizes the bounded derivative initialization (BDI) in conjunction with the vorticity method to accurately determine the hurricane vortex dynamic structure based on the single Doppler radar wind fields retrieved from the ground-based velocity track display (GBVTD) technique. The GBVTD technique retrieves the reliable rotational wind and vorticity of a tropical cyclone (TC) from single Doppler radar data. Based on the momentum conservation, the vorticity method derives the hurricane divergent wind/vertical velocity from the high temporal and spatial vorticity variations retrieved by GBVTD. BDI combines the divergent wind field inferred dynamically and the rotational wind observed from single Doppler radar data to determine the total wind field, including the vertical velocity in a hurricane vortex. BDI is also used to smoothly insert the derived hurricane vortex into environmental flows defined by forecast fields from larger scale models. The MM5 four-dimensional data assimilation system (FDDA) is used to nudge to the derived smooth kinematic wind fields in order to retrieve unobserved fields such as temperature and moisture fields. The balanced hurricane vortex with thermodynamic and moisture fields is used as the initial condition for the simulation of hurricane Danny with high resolution MM5/WRF models.
Session 9D, Tropical Cyclone Simulation: Initialization and Assimilation (Parallel with Sessions 9A, 9B, and 9C)
Wednesday, 1 May 2002, 11:00 AM-12:30 PM
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