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Hurricane Humberto (22-24 September 2001)

Coordinated NOAA and NASA aircraft observations in Hurricane Humberto from GPS dropsondes, AXBTs, Doppler radars, stepped frequency microwave radiometers (SFMRs), a scanning radar altimeter ( SRA) and other remotes sensors provide an observational database for the development of the next-generation high resolution TC numerical models.

The storm changed structure and intensity as it interacted with the mid-latitude environment and it passed through an oceanic eddy field and approached the Gulf Stream axis. Air-sea interactio n processes played a role in the evolving storm structure over the three days of aircraft observations from an asymmetric system with major mid-latitude environmental interactions to a more symmetric system. Subsequent to the observation period, the symm etric system developed an eye at nearly 40 N as it moved eastward along the Gulf Stream axis.

Major accomplishments from the experiments included a complete three-dimensional mapping of the storm within 1000 km of the center, from 100 m deep in the ocean to 65,000 ft in the atmosphere . Highlights of this three-day experiment include:

  • During the missions Humberto intensified to tropical storm strength on 22 September, to hurricane CAT 2 strength on23 September, and back to CAT 1 on 24 September.
  • Atmospheric and oceanic profiling within 1000 km of the storm center from the research aircraft and the G-IV. Over the three days 305 GPS dropsondes and 90 AXBTs were deployed, of which 8%of the dropsondes (25) failed to give wind data, and 12% of the AXBTs (11) failed to give ocean thermal profiles.
  • The research carried airborne Doppler radars providing full three-dimensional mapping of the wind field, including the two NOAA WP-3D X-band (Tail) Doppler radars, NASA DC-8 Ku/Ka-band dual-polarized (PR-2) Doppler radar scanning a swath ±45° on either side of the aircraft track, and the NASA ER-2 X-band Doppler radar (E-DOP) providing a vertical cross-section of vertical and horizontal velocities along the aircraft track.
  • Detailed microphysics measurements on two aircraft including precipitation size particles to CN/CCN measurements on N42RF and ice particle measurements on the NASA DC-8.
  • Two-dimensional wave spectra within 150 km of the storm center using the NASA Scanning Radar Altimeter (SRA) on N43RF.
  • Surface wind speed estimates from stepped frequency microwave radiometers on N42RF and N43RF.
  • Remote sensed thermal, moisture, and aerosol fields from the NASA DC-8 and ER-2.
  • First dual-polarized, dual-wavelength (Ka- and Ku-band) radar data collected in a TC.

    Storm/ Date Aircraft (Duration) Altitude Experiment/ Pattern Comments (expendables)
    Humberto
    22 September N42RF (8.9 h) mission summaryPDF(572 Kb)
    one minute listing
    GPS dropsondes
    DC-8 (9 h) mission summary
    GPS dropsondes
    ER-2 (7 h)

    WC-130

    14 kft

    37 kft

    65 kft

    5000 ft

    		3-plane XCDX/QPE Experiment.

    N42RF, DC-8, and ER-2 within 150 nm radius of center.
    • Tropical Storm Humberto intensifies to near hurricane strength.
      (18 AXBT, 41 GPS sondes)
    • N43RF returns to MacDill AFB from Huatulco, MX.
    23 September N43RF (8.9 h) mission summaryPDF(572 Kb)
    one minute listing
    GPS dropsondes
    AXBTs
    N42RF (8.9 h) mission summaryPDF(1.1 Mb)
    one minute listing
    GPS dropsondes
    DC-8 (9 h) mission summary
    GPS dropsondes
    ER-2 (7 h)

    WC-130

    N49RF (9 h)
    mission summaryPDF(1.1Mb)
    GPS dropsondes

    6 kft

    13 kft

    28-37 kft

    65 kft

    10 kft

    45 kft

    4-plane COVES Experiment.

    N42RF, N43RF, DC-8, and ER-2 within 400 nm radius of center.

    Synoptic Surveillance
    • Humberto strengthens to category 2 hurricane during the mission
      (36 AXBT, 134 GPS sondes)
    • N42RF and N43RF recover in Wilmington, NC to increase on station time.
    • DC-8 has air-traffic control problems on first leg reulting in the aircraft staying at 28 kft until passing through the N eyewall where they climbed to 37 kft.
    • N49RF mission delayed mission start 1.25 h because of engine problem.
    24 September N43RF (8.9 h) mission summaryPDF(72 Kb)
    one minute listing
    GPS dropsondes
    N42RF (8.9 h) mission summaryPDF (1.1Mb)
    one minute listing
    GPS dropsondes
    AXBTs
    DC-8 (9 h) mission summary
    GPS dropsondes
    ER-2 (7 h)

    N49RF (9 h)
    mission summaryPDF(1 Mb)
    GPS dropsondes

    6 kft

    13 kft

    37 kft

    65 kft

    45 kft

    4-plane COVES Experiment.

    N42RF, N43RF, DC-8, and ER-2 within 400 nm radius of center.

    Synoptic Surveillance
    • N42RF and N43RF recover in Wilmington, NC. Return to MacDill AFB on 25 September to increase on station time.
    • N49RF recovers in Savannah, GA after completing the surveillance mission to check engine problem that delayed previous day mission. return to MacDill AFB 25 September.
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