Latitudinal variation of aerosol optical depths from northern Arabian Sea to Antarctica

• Main Authors: Vinoj, V, Anjan, Anjit, Sudhakar, M, Satheesh, SK, Srinivasan, J, Moorthy, Krishna K
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2007
• Subjects: Centre for Atmospheric & Oceanic Sciences; Indian; Southern Ocean; Antarc*; Antarctica
• Online Access: http://eprints.iisc.ernet.in/11579/; http://eprints.iisc.ernet.in/11579/1/Latitudinal_variation.pdf; http://www.agu.org/pubs/crossref/2007/2007GL029419.shtml

Measurements of the spectral aerosol optical depths (AODs) were made over the Arabian Sea, Indian Ocean, Southern Ocean, and Antarctica during a trans-continental cruise experiment conducted during January to April 2006. Our investigations show that AODs (at 500 nm) remain low (≤0.1) and steady in the Southern Indian Ocean (20°S to 40°S). In contrast, large latitudinal gradients exist north of 20°S. The AODs increase nearly exponentially from ∼0.1 near Antarctica to reach a value as high as 0.7 in the northern Arabian Sea (∼15°N). The latitudinal gradients were larger in summer than in winter. The comparison of measured daily optical depths with those retrieved from MODIS satellite sensor showed good agreement (within ∼0.02) for regions north of 40°S. The AODs were higher over remote oceans between 40°S to 60°S (MODIS observations) latitudes as a result of enhanced sea-salt production due to high winds associated with the ‘Roaring Forties.’