SDS & Hurricanes
Impact on hurricanes
Dust could impact the dynamics of hurricanes and tropical cyclones and their formation. The overall dimension of both impacts is not yet understood well.
Cyclone Catarina in the South Atlantic, 2004; NASA
Atlantic tropical cyclone activity varies strongly over time. The interannual variation could be linked to the atmospheric dust transport over the North Atlantic Ocean- the mean dust coverage is inversely correlated with the tropical cyclone activity [1]. In 2006 and 2007 an unusually large amount of dust over the North Atlantic Ocean lead to very few tropical cyclones [2]. A reason could be the blocking of the incoming sunlight due to the dust particles, which leads to cooling of the North Atlantic Ocean [2]. Including this radiation-dust interactions simulations have shown a discrepancy of the position of the cyclone in the model after seven days [3].
Additionally the dust particles can act as nuclei resulting in clouds and raindrops within a hurricane. Depending on the age of the hurricane this can weaken or strengthen it [2]. A young storm could be intensified by the additional raindroplets, because they are a key part of its internal heat engine [2]. Additional particles lifted into an older cyclone can induce a shrinking of the eye (due to evaporative cooling) and hence an increase in the wind (eye-wall intensity) [4, 5]. Warm rain can suppress the overall strength of the hurricane [4]. Simulation has shown a large difference in storm intensity by up to 22 hPa based on the nuclei-concentration [6]. A seeded simulation of Katrina has shown a weakening in the hurricane surface winds [4].
The formation of hurricanes depends on many factors such as winds, sea-surface temperature and humidity, including dust. Hurricanes are frequently born very close to the Sahara desert, in Atlantic waters in front of the west coast of Africa, where Saharan dust could impact the early phase of hurricanes [7].
Publications
[1] A.T. Evan, J. Dunion, J.A. Foley, A.K. Heidinger, C.S. Velden; New evidence for a relationship between Atlantic tropical cyclone activity and African dust outbreaks; Geophysical Research Letters 33; 2006
[2] D. Sun, K.M. Lau, M. Kafatos; Contrasting the 2007 and 2005 hurricane seasons: Evidence of possible impacts of Saharan dry air and dust on tropical cyclone activity in the Atlantic basin; Geophysical Research Letters 35; 2008
[3] S. Nickovic, C. Perez, O. Jorba, J.M. Baldasano; Atlantic tropical cyclones and Saharan dust: a simulation study; Geophysical Research Abstracts 10, EGU2008-A-06697; 2008
[4] D. Rosenfeld, A. Khain, B. Lynn, W.L.Woodley; Simulation of hurricane response to suppression of warm rain by sub-micron aerosols; Atmospheric Chemistry and Physics 7, p. 3411–3424; 2007
[5] H. Zhang, G.M. McFarquhar, W.R. Cotton, Y. Deng; Direct and indirect impacts of Saharan dust acting as cloud condensation nuclei on tropical cyclone eyewall development; Geophysical Research Letters 36; 2009
[6] H. Zhang, G.M. McFarquhar, S.M. Saleeby, W.R. Cotton; Impacts of Saharan dust as CCN on the evolution of an idealized tropical cyclone; Geophysical Research Letters 34; 2007
[7] G.S. Jenkins, A.S. Pratt, A. Heymsfield; Possible linkages between Saharan dust and tropical cyclone rain band invigoration in the eastern Atlantic during NAMMA-06; Geophysical Research Letters 35; 2008
Publication list in alphabetical order (including publications from above):
bibliography-hurricanes [pdf, 70 kB]