THE IMPACT OF OPERATIONAL SYNOPTIC SURVEILLANCE MISSIONS ON OPERATIONAL HURRICANE TRACK FORECAST MODELS

Principal Investigator: Sim D. Aberson
Collaborating Scientist: Jimmy Franklin
Objective:
To evaluate the impact of special environmental observations on the objective hurricane track forecast guidance available to the National Hurricane Center.
Background:
Improved prediction of hurricane motion requires more information on the hurricane's large-scale environmental wind and height patterns than is typically available. While satellites can provide some wind data in the upper and lower troposphere, the middle levels are frequently almost void of observations. Operational models used for hurricane track forecasting need information from throughout the troposphere to be provide accurate TC track forecasts. As a result, operational models may fail to predict important changes of storm motion due to inadequate initial data, rather than inadequate physics of the prediction models.

HRD's "Synoptic Flow" experiments use dropwindsondes to gather vertical profiles of wind, temperature, and humidity within 1,000 km of hurricanes. The experiment is typically conducted over the data-sparse oceanic regions of the western Atlantic or Gulf of Mexico roughly 48-72 hours before the projected landfall of a mature hurricane on the coast of the United States. The dropwindsondes define the hurricane's surrounding large-scale flow, particularly in the 300-700 mb middle tropospheric layer - the layer most directly related to tropical cyclone motion.

Analysis Methodology:
From 1982-1996, the two NOAA WP-3D aircraft were equipped with Omega dropwindsonde (ODW) systems. Using the historical sample of Synoptic Flow experiments conducted by HRD from 1982-1993, an assessment was made of the impact of ODW data on three dynamical hurricane track models providing guidance to the forecasters at NHC: HRD's barotropic VICBAR model, NCEP's global spectral model, and the GFDL hurricane model.

Accomplishments:
Results from 1997-98 operational synoptic surveillance missions are similar and can be seen here.

Key reference:

Burpee, R. W., J. L. Franklin, S. J. Lord, R.E. Tuleya, and S.D. Aberson, 1996: "The impact of Omega dropwindsondes on operational hurricane track forecast models." Bull. Amer. Meteor. Soc., 77, 925-933.

Franklin, J. L., and M. DeMaria, 1992: "The impact of Omega dropwindsonde observations on barotropic hurricane track forecasts." Mon. Wea. Rev., 120, 381-391.

Aberson, S.D., and M. DeMaria, 1994: "Verification of a nested barotropic hurricane track forecast model (VICBAR)." Mon. Wea. Rev., 122, 2804-2815.

Bender, M. A., R. J. Ross, R. E. Tuleya, and Y. Kurihara, 1999: "Improvements in tropical cyclone track and intensity forecasts using the GFDL initialization system" Mon. Wea. Rev., 121, 2046-2061.

Lord, S. J., 1993: "Recent developments in troical cyclone track forecasting with the NMC global analysis and forecasting system." Preprints of the 20th Conference on Hurricanes and Tropical Meteorology, San Antonio, Amer. Meteor. Soc., 290-291.

Hock, T.F., and J.L.Franklin, 1999: "The NCAR GPS dropwindsonde." Bull. American Met. Soc.,80, 407-420.

Aberson, S.D., and J.L.Franklin, 1999: "Impact on hurricane track and intensity forecasts of GPS dropwindsondes observations from the first-season fligs of the NOAA Gulfstream IV jet aircraft." Bull. American Met. Soc.,80, 421-428.

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Last modified: 24 May 1999.
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