JP1.13
Use of radar data for TC initialization and intensity forecasts
Jin-Luen Lee, NOAA/ESRL/GSD, Boulder, CO; and A. E. MacDonald, W. Lee, and W. Wang
Hurricane track forecasts improve steadily over the last several decades.
However, intensity forecasts show very little improvement
over the last decade, partially, because small-scale inner-core circulation can not be properly resolved
by satellite observations.
To improve intensity forecasts, it is important to use high-resolution Doppler radar data
to properly initialize inner-core circulation for high-resolution numerical models.
A technique is developed for initialization of a hurricane vortex
using horizontal velocities through a deep layer of the atmosphere
obtained from Doppler radar.
The technique uses two new innovations.
The first is the use of the mesoscale vorticity equation
to diagnose the vertical velocity and divergent wind.
The second is the use of the Bounded Derivative Initialization
to obtain two dynamic constraints, one each for gravity and sound waves.
With the fast waves controlled, a nonhydrostatic model can be initialized
to allow a smooth and balanced start.
The technique is tested using the 1.5 km resolution MM5 model
with radar data from Hurricane Danny as it approached the Gulf Coast in 1997.
Numerical results show positive radar data impacts on track and intensity forecasts.
The initialization scheme correctly inserts the observed storm derived from radar data
in the right location. After initialization, the forecast storm track closely follows the
actual storm track observed from Doppler radar.
Comparisons of forecast winds and radar wind measurements show the use of radar data
substantially improves the intensity and horizontal structure of forecast wind fields.
Joint Poster Session 1, Tropical Cyclones and Probability/Statistics Posters
Monday, 21 January 2008, 2:30 PM-4:00 PM, Exhibit Hall B
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