TCAR - Typhoon Committee

First
TCAR
CHAPTER 5 - RESEARCH FELLOWSHIP TECHNICAL REPORT
Fig.4. Flowchart of the CMA’s recent TS prediction
system
The new vortex initialization scheme has
following advantages :
• Model generated vortex is more
consistent with model dynamics, and less
adjustment needed once forecast starts
• Dynamic structures of vortex in the first
guess will be maintained in relocation
procedure.
• The procedure of TC initialization is
finished before the analysis assimilation,
So the first guess field is more consistent
with observation data, and less data are
rejected around TC.
This new TS prediction system had been tested
for 506 cases of 23 TSs with various intensities
in WNPAC of 2006 to compare with the previous
one. Track forecast verification indicated very
encouraging improvement in accuracy of track
forecasts issued by new system : there is a
decrease in the average track error of 12-23% in
the 12 to 120 hour time period. Fig. 5. showed
the experiment results for 23 TSs in 2006.
Mean Track Error (km)
800
700
600
500
400
300
200
100
0
bogus
new
6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 114 120
Forecast Time (hour)
Fig.5. Experiment results for 23 TSs in 2006. (Qu
et la, 2009)
The new TC prediction system was put into
parallel operation in 2007 TS season.
4. Analysis of CMA typhoon model forecast
results
10 TYs with complicated tracks from 2006-2009
are selected for analysing and the results are
shown as followings :
4.1. TY 0608 SAOMAI
SAOMAI formed as tropical depression (TD)
in sea water southeast of Guam on 00 UTC
05/08/2006. It moved westnorthwestward and
2009
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