Relation Sahran Dust And Hurricanes


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Relation Sahran Dust And Hurricanes

  1. 1. The Relation between Saharan Dust and Hurricanes Briefing Slides, Melke Mersie A. Melke
  2. 2. Topics <ul><li>Saharan dust (Saharan Air Layer: SAL) transport </li></ul><ul><li>Saharan dust collection spectrum in the western hemisphere and North Atlantic Ocean (NAO) </li></ul><ul><li>Long term observed effects </li></ul><ul><li>Hurricane with positive relation with Saharan dust </li></ul><ul><li>Concluding Remarks </li></ul><ul><li>References </li></ul>Briefing Slides, Melke
  3. 3. Saharan dust source : Darkest area (Bode’le’) is the highest source with Aerosol index 30 Briefing Slides, Melke Annual Aerosol Index for the Sahara, derived from TOMS (Goudie, Middleton, 2001)
  4. 4. Probable Trajectories of Saharan dust Briefing Slides, Melke Probable trajectories of soil aerosol transport based on quartz isotope ratio (Michalak, 17 December 2004)
  5. 5. Saharan dust transport Briefing Slides, Melke Dust transport over the North Atlantic from North Africa in the northern hemisphere summer and winter (Michalak,17 December 2004)
  6. 6. Seasonal behavior of Saharan dust transport Briefing Slides, Melke Seasonality of dust events over the North Atlantic and the west coast of Africa (Goudie, Middleton, 2001)
  7. 7. Dust deposition Briefing Slides, Melke Model of dust transport and accumulation over the North Atlantic offshore from the Sahara. (A) Annual mass budget at 15–24 deg North in 10 mega tonnes/year. (B) Accumulation rate of dust in deep-sea sediments in centimeters per 1000 years. (Goudie, Middleton, 2001).
  8. 8. Saharan dust transport satellite image Briefing Slides, Melke Extricated dust plume over west Africa (Michalak, 17 December 2004)
  9. 9. Global Sea surface temperature Briefing Slides, Melke Global occurrence of cyclone activity (Michalak, 17 December 2004)
  10. 10. Long term observed effects Briefing SLides, Melke Mean vertical shear locus 850 hPa Relative Humidity locus Time Series of Standardized mean peak intensity locus Time series of standardized mean peak intensity locus Standardized Sahel Rainfall locus SAL effect index (SE I) locus Graphical representation of the long term relation between Saharan Air layer effect Index, Sahel rainfall quantity and hurricane intensity over the NAO (Wu, 2007)
  11. 11. Long term observed negative effects Briefing Slides, Melke Long term observed relationship between NAO hurricanes and Saharan Dust( Wu, 2007)
  12. 12. Hurricane with a positive relation with Saharan dust Briefing Slides, Melke Despite the presence of warm (b, d, f, h) and very dry air (not shown) to the north and west of the storm, Helene intensifies into a Category 1 hurricane by 16 September and a Category 3 hurricane by 18 September. (Braun, Shie, 2008) Hurricane FLORENCE Hurricane GORDON Hurricane Helene Hurricane Florence Hurricane GORDON Hurricane Helene Warm Saharan Air Layer Warm Saharan Air Layer
  13. 13. Concluding Remarks <ul><li>Saharan dust annually commutes to NAO region </li></ul><ul><li>The Saharan dust budget over the NAO is seasonally variable </li></ul><ul><li>On the long term Saharan dust is observed to impede Hurricane intensification </li></ul><ul><li>Hurricanes that intensify despite Saharan dust are observed </li></ul><ul><li>The relation between the two phenomena is case dependant. </li></ul>Briefing Slides, Melke
  14. 14. Questions <ul><li> Which trajectory of the Saharan dust has the most amount of mineral dust? </li></ul><ul><ul><li>Trajectory to the North Atlantic Ocean (NAO) ☺ </li></ul></ul><ul><ul><li>Trajectory to the Mediterranean </li></ul></ul><ul><ul><li>Trajectory to the Middle East </li></ul></ul><ul><ul><li>What is the relation between Saharan dust and NAO Hurricanes? </li></ul></ul><ul><ul><li>There is no relation at all between the two. </li></ul></ul><ul><ul><li>Saharan dust impedes NAO hurricane </li></ul></ul><ul><ul><li>Saharan dust intensifies NAO hurricane </li></ul></ul><ul><ul><li>The relation is case dependant and differs from Hurricane to Hurricane ☺ </li></ul></ul>Briefing Slides, Melke
  15. 15. References <ul><li>Braun, S.A. and Shie, C.L. ( 2008, May 1). Examination of the influence of the Saharan Air Layer on hurricanes using data from TRMM, MODIS, and AIRS. Paper presented at the 28th Conference on Hurricanes and Tropical Meteorology, Palms E. </li></ul><ul><li>Goudie, A.S., Middelton, N.J. (2001, May 14). Saharan Dust storms: Nature and Consequences. Earth Science Reviews. 56, 179-204. </li></ul><ul><li>Michalak, A.E. (2004, 17 December). Properties and Influences of the Saharan Air Layer on Tropical Cyclogenesis. Retrieved 21 December 2008, from Colorado University, Student and Graduate Assistant website: </li></ul><ul><li>Wu, L. (2007, 16 May). Impact of Saharan Air Layer on Hurricane Intensity. Geophysical Research Letters. 34, 9. </li></ul>Briefing Slides, Melke