PREDICTION OF MODEL PERFORMANCE
Principal Investigator:
Sim D. Aberson
Objective:
Evaluation of methods to provide estimates of model error in operational
forecasts of tropical cyclone motion.
Rationale:
Recent years have shown a slow and steady increase in skill of
operational tropical cyclone track forecasts. A number of operational track
forecast models have average skill approaching 40%, yet none of them performs
well consistently, and a serious challenge for operational forecasters is
to choose which of the various possibilities presented by the ensemble of
different models is the most likely to occur. Not only should the
guidance itself be presented to forecasters, but an estimate of the
confidence which should be placed in that forecast as well. Thus, a method
for the Prediction of Model Performance (POMP), and methods in ensemble
forecasting are studied.
Method:
A method to objectively estimate the confidence in track forecasts
has been developed for the ensemble of models currently in use. Data from
the synoptic situation in the environment of each tropical cyclone,
climatological data, and past performance of each model are analyzed from the
1989 - 1995 hurricane seasons to allow a linear discriminant analysis to
differentiate between forecasts which are expected to perform well from
those expected to be poor, giving the forecasters an object estimate of
confidence of the individual forecasts.
(Fig. 1)
Accomplishment:
The linear discriminant analysis for the HRD VICBAR model has shown that
individual forecasts which are expected to be poor can be differentiated
from those expected to be good, allowing forecasters to disregard the
expected-poor information and improve their forecasts. Since the
ensemble mean forecasts are, on average, better than forecasts from
individual models, this information can be used to provide
weighted-ensemble mean predictions to forecasters.
The following manuscript has been submitted for publication:
Aberson, S. D., 1997: Five day tropical cyclone track forecasts
in the North Atlantic basin. Submitted to Wea. Forecasting.
Key references:
Aberson, S. D., and M. DeMaria, 1994: Verification of a nested
barotropic hurricane track forecast model (VICBAR). Mon. Wea. Rev.,
122, 2804-2815.
Aberson, S. D., 1997: The prediction of the performance of a
nested barotropic hurricane track forecast model. Wea. Forecasting,
12, 24-30.
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Last modified: 6/26/97