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Aircraft Expendables

  • Dropwindsondes

    Dropwindsondes are deployed from the aircraft and drift down on a parachute measuring vertical profiles of pressure, temperature, humidity and wind as they fall. They are released from the both the WP-3D and G-IV aircraft over data-sparse oceanic regions. From 1982 until 1997, HRD used Omega dropwindsondes (ODWs) that employed the very low frequency Omega navigation signals to estimate the sondes motion relative to the aircraft, and subsequently calculate the wind. NOAA now uses new sondes that employ the more accurate GPS navigation to estimate winds.

    A deployed sonde and chute

    Example: Eye sounding in Hurricane Jimena (1993)

  • Airborne eXpendable BathyThermographs (AXBT)
  • Airborne eXpendable Current Profilers (AXCP)
  • Airborne eXpendable Conductivity Temperature and Depth probes (AXCTD)
  • Drifting buoys

    Oceanographic instruments may be deployed from the WP-3D aircraft either from external chutes using explosive cads or from an internal drop chute. They activate upon hitting the ocean surface and radio sea temperature, salinity, and current information back to computers aboard the aircraft.

Exploded view of an AXBT


Aberson, S.D. 2002 "Two years of operational hurricane synoptic surveillance." Weather and Forecasting, 17(5) pp.1101-1110

Rogers, R.F., S.D. Aberson, J. Kaplan, and S.B. Goldenberg. 2002 "A pronounced upper-tropospheric warm anomaly encountered by the NOAA Gulfstream-IV aircraft in the vicinity of deep convection." Monthly Weather Review, 130(1) pp.180-187

Aberson, S.D., and J.L. Franklin. 1999 "Impact on hurricane track and intensity forecasts of GPS dropwindsonde observations from the first-season flights of the NOAA Gulfstream-IV jet aircraft." Bulletin of the American Meteorological Society, 80(3) pp.421-428

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." Bulletin of the American Meteorological Society, 77(5) pp.925-933

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." Monthly Weather Review, 124(1) pp.64-84

Burpee, R.W., S.D. Aberson, P.G. Black, M. DeMaria, J.L. Franklin, J.S. Griffin, S.H. Houston, J. Kaplan, S.J. Lord, F.D. Marks, M.D. Powell, and H.E. Willoughby. 1994 "Real-time guidance provided by NOAA's Hurricane Research Division to forecasters during Emily of 1993." Bulletin of the American Meteorological Society, 75(10) pp.1765-1783

Franklin, J., S. Lord, and F. Marks, 1988 "Dropwindsonde and radar observations of the eye of Hurricane Gloria (1985)." Mon. Wea. Rev., 116, pp.1237-1244.

Contact information on Dropwindsondes mail to :,
Contact information on AXBTS and buoys mail to :

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Updated June 16, 2003

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