Last year, OMEGA was used for the first time to examine the structure and evolution of Hurricane Floyd (1999). The first simulation of Floyd was conducted in an operational forecast mode; additional simulations exploiting both the static as well as the dynamic grid adaptation options in OMEGA were performed later as part of a sensitivity / capability study. While a horizontal grid resolution ranging from about 100 km down to about 30 km were employed in the operational run, resolutions down to about 15 km were used in the sensitivity study to explicitly model the structure of the inner core. Each 72 hour OMEGA simulation was initialized with meteorological conditions and sea surface temperature (SST) obtained from the NOGAPS analysis with the lateral boundary conditions updated every 12 hours using the NOGAPS forecast. The overall results were very good for a first application with the model correctly capturing the re-curvature off the Florida coast and the land-fall near Cape Fear, NC.
The OMEGA forecasted track has been compared against the operational tracks used at the NOAA National Hurricane Center (NHC). Figures 1 and 2 show the OMEGA forecasted track along with the operational tracks from the three best models used at the NHC: the NOAA Geophysical Fluid Dynamics Laboratory (GFDL) hurricane model; the US Navy Operational Global Analysis and Prediction System (NOGAPS); and the United Kingdom Meteorology Office (UKMO) forecast model. The figures show the OMEGA forecast initialized at 0000Z on September 13 (yellow) along with the "early" run (GFDI, NGPI, UKMI) 72 hour forecasted tracks (brown). Figure 1 shows the tracks initialized at 0000Z on the 13th; Figure 2 shows the tracks initialized at 0000Z on the 14th.
Comparison of observed and simulated rainfall distribution valid September 14-16, 1999. The observed precipitation (Figure 4) is plotted in inches with maximum indicated in blue and minimum indicated in red; the simulated precipitation (Figure 3) for the simulation starting on 14th are also plotted in inches (Observations courtesy of Dr. Sethu Raman.)
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| Figure 1: Tracks Initialized at 0000Z on September 13th |
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| Figure 2: Tracks Initialized at 0000Z on September 14th |
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| Figure 3: Simulated Precipitation for September 14th |
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| Figure 4: Observed Precipitation for September 14th |
An animation of the dynamically adapting simulation of Hurricane Floyd
may also be viewed by clicking on the following link.
This animation is a Java applet and consists of a large number of frames
and so may take some time to load.