35th Anniversary of first Synoptic Flow mission

Track of NOAA42 north of Hurricane Debby on Sept. 14, 1982.

On September 14, 1982, NOAA42 flew the first Synoptic Flow Experiment around Hurricane Debby.  The idea behind the experiment was to fly a large-scale pattern around a hurricane while releasing dropwindsondes at regular intervals.  This would create a three-dimensional map of the winds steering the storm.  The data would be entered into hurricane track forecast models and (ideally) improve the track forecast.

The concept for such missions was first formulated by Dr. Robert Burpee at HRD when he participated in the GATE experiment in 1974.  Responsible for the daily weather briefing for the various participants, he found the use of Omega dropwindsondes (ODWs) by GATE aircraft invaluable in mapping the wind field over the experiment area.  He thought similar use of ODWs around a hurricane would improve the computer models’ accuracy.  An early attempt was made by the NASA CV-990 in 1979 during Hurricane Frederic, but the data wasn’t made available in real time to computer modelers.

It took several more years to work out the logistics, but by 1982 things were ready for a real-time try.  That year’s hurricane season had been very quiet until September.  Finally, Tropical Storm Debby formed north of Hispañola and was moving east of the Bahamas strengthening into a hurricane.  It was also far enough away from land to avoid complications to the track models.  HRD scientists on the flight were trained in how to encode the dropwindsonde data into a standard format and for transmission by satellite link to NOAA’s National Meteorological Center and National Hurricane Center.

Combined tracks of 19820915H1 and 19820915I1 Synoptic Flow missions with ODW drops located at open circles.

Another Synoptic Flow Experiment was flown the next day, this time with both NOAA42 and NOAA43.  The information enabled the hurricane specialists at NHC to subjectively alter their forecast based on the positions of upper-level troughs and lows north of Debby.  However, the numerical models of that time were of insufficient resolution to be able to model the various elements influencing Debby.  Later Synoptic Flow Experiments were flown when global models were improved enough to make use of the dropwindsonde data.

A later study by Burpee and colleagues showed that such missions could reduce track errors by 16-30%.  This success led NOAA to acquire a high-altitude G-IV jet to accomplish Synoptic Surveillance missions on an operational basis.

References

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

Burpee, R. W., D. G. Marks, and R. T. Merrill, 1984:  An assessment of Omega Dropwindsonde data in track forecasts of Hurricane Debby (1982).  Bull. Amer. Met. Soc., 65, 1050-1058.

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

Franklin, J. L., and S. J. Lord, 1988:  Comparison of VAS and Omega Dropwindsonde thermodynamic data in the environment of Hurricane Debby (1982).  Mon. Wea. Rev., 116, 1690-1701.

Franklin, J. L., S. E. Feuer, J. Kaplan, and S. D. Aberson, 1996:  Tropical cyclone motion and surrounding flow relationships:  Searching for beta gyres in Omega Dropwindsonde datasets.  Mon. Wea. Rev., 124, 64-84.

Lord, S. J., and J. L. Franklin, 1987:  The environment of Hurricane Debby (1982).  Part I:  Winds.  Mon. Wea. Rev., 115, 2760-2780.

Lord, S. J., and J. L. Franklin, 1990:  The environment of Hurricane Debby (1982).  Part II:  Thermodynamic fields.  Mon. Wea. Rev., 118, 1444-1459.

Marks, F. D., Jr., and R. A. Houze, 1984:  Airborne Doppler radar observations in Hurricane Debby.  Bull. Amer. Met. Soc., 65, 569-582.

Shapiro, L. J., and J. L. Franklin, 1999:  Potential vorticity asymmetries and tropical cyclone motion.  Mon. Wea. Rev., 127, 124-131.

Willoughby, H. E., F. D. Marks, Jr., and R. J. Feinberg, 1984:  Stationary and moving convective bands in hurricanes.  J. Atmos. Sci., 41, 3189-3211.

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