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Principle Investigator : Jason Dunion (HRD)

SeaWiFS/NASA/GSFC

Team Members:

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

• Improve our understanding of the mechanisms by which the Saharan Air Layer's (SAL's) dry air, mid-level easterly jet, and embedded mineral dust affect Atlantic tropical cyclone genesis and intensity change;

• Include the moisture information from the GPS dropwindsondes in operational parallel runs of the NOAA Global Forecast System (GFS) model. Assess the impact of this data on the GFS (and GFDL) initial/forecast humidity fields and its forecasts of TC track and intensity will be assessed;

• Improve the representation of the SAL's dry air and mid-level easterly jet (enhanced vertical wind shear) 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 mechanisms that lead to strong SAL outbreaks over Africa;

• Investigate the mechanisms by which the SAL maintains its thermodynamic structure;

• Investigate the effect of the SAL's suspended mineral dust on cloud microphysics;

Methods:

• Conduct the SALEX experiment using NOAA's P-3 Orion and G-IV aircraft as described in the HRD hurricane field program (HFP);

• SAL monitoring: GOES, MSG, SSM/I, AMSU, Terra, and Aqua satellites

• SAL sampling: GPS dropsondes;

Accomplishments:

• Developed automated geostationary satellite imagery (GOES-10 and Meteosat-8) to track the SAL continuously. These new products include split window IR, mid-level water vapor, and multi-spectral true color satellite imagery and are available in real-time at the UW-CIMSS tropical cyclone website:
  http://cimss.ssec.wisc.edu/tropic/real-time/wavetrak/sal.html
  

• Conducted first-ever SALEX missions during the 2005 Atlantic hurricane season that used the NOAA G-IV jet to investigate the environments of TS Irene and pre Tropical Depression 19 and their interactions with the SAL:
  1. Aug. 07, 2005 (G-IV jet)
  2. Aug. 08, 2005 (G-IV jet)
  3. Sep. 27, 2005 (G-IV jet)
  4. Sep. 28, 2005 (G-IV jet)

• Successfully submitted a proposal to the NOAA/Joint Hurricane Testbed program to "assimilate moisture information from GPS dropwindsondes launched from the NOAA G-IV jet in operational parallel runs of the NOAA GFS model and assess the impact of this data on the GFS initial/forecast humidity fields and its forecasts of TC track and intensity." This JHT project began in 2005 and will continue through the 2006 Atlantic hurricane season.

• Conducted SALEX missions during the 2006 Atlantic hurricane season that used the NOAA P-3 Orion and G-IV jet to investigate the environments of Tropical Storm Debby and Hurricane Helene and their interactions with the SAL:
  1. Aug. 25, 2005 (G-IV jet)
  2. Aug. 26, 2006 (G-IV jet)
  3. Sep. 15, 2006 (G-IV jet)
  4. Sep. 16, 2006 (G-IV jet)
  5. Sep. 18, 2006 (P-3 Orion; G-IV jet)
  6. Sep. 20, 2006 (P-3 Orion; G-IV jet)

Evan, A.T., J. Dunion, J.A. Foley, A.K. Heidinger, and C.S. Velden, 2006: New evidence for a relationship between Atlantic tropical cyclone activity and African dust outbreaks. J. Geophys. Res. 33 L19813, 1-5.

Dunion, J.P., J.D. Hawkins, and C.S. Velden, 2006: Hunting for Saharan Air with the NOAA GI-IV Jet. AMS 27^th Conference on Hurricanes and Tropical Meteorology, Monterey, CA, American Meteorological Society.

Dunion, J.P., and S.D. Aberson, 2006: Assimilating moisture information from Global Positioning System (GPS) dropwindsondes into the NOAA Global Forecast System, 60^th Annual Interdepartmental Hurricane Conference, Mobile, AL, Office of Fed. Coord. For Meteor. Services and Supporting Research, NOAA.

Dunion, J.P., C.S. Velden, J.D. Hawkins, and J.R. Parrish, 2004: The Saharan Air Layer - Insights from the 2002 and 2003 Atlantic hurricane seasons. AMS 26^th Conference on Hurricanes and Tropical Meteorology, Miami, FL, American Meteorological Society, 495-496.

Prospero, J.M., 2004, J.P. Dunion, and C.W. Landsea, 2004: The Long-Term (1965-2003) Relationship Between Dust Concentrations in the Trade Winds at Barbados and Tropical Cyclone and Hurricane Activity in the Atlantic and Caribbean. AGU Fall Meeting, San Francisco, CA, American Geophysical Union.

Dunion, J.P., and C.S. Velden, 2004: The impact of the Saharan Air Layer on Atlantic tropical cyclone activity. Bull. Amer. Meteor. Soc., 85 no. 3 , 353-365.

Future Work:

• Conduct additional SALEX missions during the 2006 Atlantic hurricane season that utilize the NOAA P-3 Orion and G-IV aircraft. These missions will be coordinated with NASA's NAMMA program (operating out of Cape Verde and western North Africa) and the multi-national African Monsoon Multidisciplinary Analyses (AMMA) campaign being conducted in North Africa.

• Continue to assimilate moisture information from the GPS dropwindsondes launched from the NOAA G-IV jet in operational parallel runs of the NOAA GFS model and assess the impact of this data on the GFS initial/forecast humidity fields and its forecasts of TC track and intensity;

• Develop a new mean Jordan tropical sounding (dry SAL vs moist non-SAL);

• Develop an improved humidity parameter for use in the SHIPS hurricane intensity forecast model;

Last modified: 10/11/2006