TCAR - Typhoon Committee

300
ESCAP/WMO
Typhoon Committee Annual Review 2009
6. Comments and conclusion
This study considered TS track forecast skill of
the CMA’s TS track prediction system including
the global model version T213L31 and vortex
initialization scheme by analysing model forecasts
for 10 TSs of complicated tracks during 2006 –
2009 in WNPAC to find model’s systematic errors
and bias, then conducting numerical experiments
for TY PARMA (0917) and TY FENGSHEN (0806)
by using CMA’s global spectral model and vortex
initialization scheme with last improvements and
modifications.
Overally, the statistic showed that the CMA’s
TS track prediction system had good forecast
skill performance in term of mean track errors
for majority of TSs with complicated tracks
considered in this study for +24h, +48h and +72h
forecast periods. However, it is obvious that in
many track forecasts there is northward bias.
Also, the track forecast errors are large when TS
changes its motion direction or speed. This could
be explained by many different factors including
limitation in model physics, model resolution,
physical parameterizations and initial conditions.
To overcome the sparity of observations in
ocean vortex initialization schemes are used for
presenting TS bogus vortex in initial conditions
to be similar to the observed TS based on the
theoretical research and observational results.
This approach brought very encouraging
improvement in TS track forecasts accuracy.
The improvement in CMA’s model track forecast
accuracy for TY FENGSHEN in EXP 2 by
better representing sea level pressure for TS
bogus vortex in vortex modification step one
again emphasied the important role of vortex
initialization scheme in TS track forecast system.
However, how to select appropriate parameters
for correctly representing TS structure and
surrounding environmental flow structure, their
intensity, their size, their interaction in vortex
initialization scheme so that this will contribute
to further improvement in model track forecast
accuracy overally and in case of TS complicated
track is still a big challenge for reseach and
experiments as results of EXP 4 for TY PARMA
showed. Further serious research should be
conducted in this aspect.
Acknowledgements
This research was financially supported by
China Meteorological Administration (CMA)
in TRCG Fellowship Scheme 2009 of WMO/
ESCAP Typhoon Committee and was carried out
in Typhoon and Marine Meteorological Forecast
Centre, National Meteorological Center (NMC) of
CMA . The authors would like to express special
thanks to Shuhong Ma, Qu Anxiang, Zhang Jin
and other staffs in NMC for providing CMA’s
typhoon model forecasts, materials, references
and very valuable supporting. Also, we are very
grateful to Hydrometeorological Service of SR
Vietnam (VHMS) and Thailand Meteorological
Department (TMD) for nominating us to CMA.
References
Davidson, N.E., J. Wadley, K. Puri, K.Kurihara
and M. Ueno, 1993 : Implementation of
JMA typhoon bogus in the BMRC tropical
prediction system. J. Meteor. Soc., Japan, 71,
437-467
Davidson, N.E. and H.C. Weber ,2000 :The
BMRC high resolution TC prediction
system:TCLAPS. Mon.Wea.Rev.,128, 1245-
1265
Heming, J.T., and A. M. Radford, 1998 : The
performance of the United Kingdom
Meteorological Office global model in
predicting the tracks of Atlantic TCs in 1995.
Mon.Wea.Rev.,126, 1323-1331
Iwasaki, T., H. Nakano, and M. Sugi, 1987 : The
performance of a typhoon track prediction
model with cumulus parameterization.
J.Meteor.Soc.Japan, 65, 555-570.
Kurihara, Y., M.A. Bender and R.J.Ross, 1993 :
An initialization scheme of hurricane models
by vortex specification. Mon.Wea.Rev., 121,
2030-2045.
Kurihara, Y., M.A. Bender, R.E. Tuleya and
R.J.Ross, 1995 : Improvement in the GDFL
hurricane prediction system. Mon.Wea.
Rev.,123, 2791-2801.
Kurihara, Y., R.E. Tuleya, and M. A. Bender, 1998
: The GFLD hurricane prediction system
and its performance in the 1995 hurricane