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Saharan Air Layer

Principle Investigator : Jason Dunion (UM-CIMAS/HRD)

SeaWiFS/NASA/GSFC

Team Members:

Sim Aberson (HRD)
Bill Barry (HRD)
Mike Black (HRD)
Neal Dorst (HRD)
Steve Feuer (HRD)
Jeff Hawkins (NRL)
John Kaplan (HRD)
Chris Landsea (HRD)
Paul Leighton (HRD)
Frank Marks (HRD)
Mark Powell (HRD)
Joseph Prospero (UM/CIMAS)
Rob Rogers (UM-CIMAS/HRD)
Chris Velden (UW/CIMSS)

Objectives:
Improve our understanding of the mechanisms by which the Saharan Air Layer’s (SAL’s) embedded mineral dust, low humidity, and low-level wind surge affect Atlantic tropical cyclone genesis and intensity change.
  • improve the representation of dry air in forecast models
  • investigate how the SAL interacts with the tropical cyclone inner core
  • improve our understanding of the SAL’s vertical structure
  • investigate the effect of mineral dust on cloud microphysics
  • improve the representation of vertical wind shear that is enhanced by the SAL surge
  • investigate the mechanisms that lead to strong SAL outbreaks over Africa
  • investigate the mechanisms by which the SAL maintains its thermodynamic structure

Methods:
  • conduct the SALEX experiment as described in the HRD hurricane field program (HFP)
  • SAL monitoring: GOES, MSG, SSM/I, AMSU, Terra, and Aqua satellites
  • SAL sampling: GPS dropsondes, LASE DIAL LIDAR (aerosol & moisture)
  • Data processing: GPS processing software, new code development to automate the ability to look at specific SAL characteristics (humidity/temperature/winds)

Accomplishments:
  • automated geostationary satellite imagery was developed to track the SAL continuously and is available in real-time
  • SALEX was added to the HRD HFP beginning in 2002


References:
Dunion, J.P., and C.S. Velden, 2003: The impact of the Saharan Air Layer on Atlantic tropical cyclone activity. Bull. Amer. Meteor. Soc., (Submitted).

Dunion, J.P., and C.S. Velden, 2003: The Impact of the Saharan Air Layer on Atlantic tropical cyclones. 57th Annual Interdepartmental Hurricane Conference. Miami, FL, Office of Fed. Coord. For Meteor. Services and Supporting Research, NOAA.

Future Work:
  • develop alternative satellite tools to replace GOES-8 coverage beyond 2002

  • develop a new Jordan sounding (SAL versus non-SAL)
  • investigate the impact of humidity data on TC track and intensity model forecasts
  • examine how effectively global models are capturing the SAL’s low humidity
  • develop an improved humidity parameter for use in SHIPS

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Last modified: 2/28/2003
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