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Title: Saharan dust as a causal factor of hemispheric asymmetry in aerosols and cloud cover over the tropical Atlantic Ocean

Meridional distribution of aerosol optical thickness (AOT) over the tropical Atlantic Ocean (30°N – 30°S) was analyzed to assess seasonal variations of meridional AOT asymmetry. Ten-year MERRA Aerosol Reanalysis (MERRAero) data (July 2002 – June 2012) confirms that the Sahara desert emits a significant amount of dust into the atmosphere over the Atlantic Ocean. Only over the Atlantic Ocean did MERRAero show that desert dust dominates other aerosol species and is responsible for meridional aerosol asymmetry between the tropical North and South Atlantic. Over the 10-year period under consideration, both MISR measurements and MERRAero data showed a pronounced meridional AOT asymmetry. The meridional AOT asymmetry, characterized by the hemispheric ratio (RAOT) of AOT averaged separately over the North and over the South Atlantic, was about 1.7. Seasonally, meridional AOT asymmetry over the Atlantic was the most pronounced between March and July, when dust presence is maximal (RAOT ranged from 2 to 2.4). There was no noticeable meridional aerosol asymmetry in total AOT from September to October. During this period the contribution of carbonaceous aerosols to total AOT in the South Atlantic was comparable to the contribution of dust aerosols to total AOT in the North Atlantic. During the same 10-yearmore » period, MODIS cloud fraction (CF) data showed that there was no noticeable asymmetry in meridional CF distribution in different seasons (the hemispheric ratio of CF ranged from 1.0 to 1.2). MODIS CF data illustrated significant cloud cover (CF of 0.7 – 0.9) with limited precipitation ability along the Saharan Air Layer.« less
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [1]
  1. Tel-Aviv Univ., Tel-Aviv (Israel). Department of Geosciences
  2. NASA Global Modeling and Assimilation Office (GSFC), Greenbelt, MD (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  4. California Inst. of Technology (CalTech), Pasadena, CA (United States). Jet Propulsion Laboratory
Publication Date:
Report Number(s):
Journal ID: ISSN 0143-1161; KP1701000
Grant/Contract Number:
Accepted Manuscript
Journal Name:
International Journal of Remote Sensing
Additional Journal Information:
Journal Volume: 36; Journal Issue: 13; Journal ID: ISSN 0143-1161
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; meridional; aerosol; tropical; Atlantic Ocean
OSTI Identifier: