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Identification of aerosol type over the Arabian Sea in the premonsoon season during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB)

Kalapureddy, MCR and Kaskaoutis, DG and Ernest Raj, P and Devara, PCS and Kambezidis, HD and Kosmopoulos, PG and Nastos, PT (2009) Identification of aerosol type over the Arabian Sea in the premonsoon season during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB). Journal of Geophysical Research: Atmospheres, 114 (17).

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Abstract

A discrimination of the different aerosol types over the Arabian Sea (AS) during the Integrated Campaign for Aerosols, Gases and Radiation Budget (ICARB-06) is made using values of aerosol optical depth (AOD) at 500 nm (AOD500) and à ngström exponent (α) in the spectral band 340-1020 nm (α340-1020). For this purpose, appropriate thresholds for AOD500 and α340-1020 are applied. It is shown that a single aerosol type in a given location over the AS can exist only under specific conditions while the presence of mixed aerosols is the usual situation. Analysis indicates that the dominant aerosol types change significantly in the different regions (coastal, middle, and far) of AS. Thus the urban/industrial aerosols are mainly observed in coastal AS, the desert dust particles occur in the middle and northern AS, while clear maritime conditions mainly occur in far AS. Spectral AOD and à ngström exponent data were analyzed to obtain information about the adequacy of the simple use of the à ngström exponent and spectral variation of a for characterizing the aerosols. Using the least squares method, α is calculated in the spectral interval 340-1020 nm along with the coefficients a1 and a2 of the second-order polynomial fit to the plotted logarithm of AOD versus the logarithm of wavelength. The results show that the spectral curvature can effectively be used as a tool for their discrimination, since the fine mode aerosols exhibit negative curvature, while the coarse mode particles exhibit positive curvature. The correlation between the coefficients a1 and a2 with the à ngström exponent, and the atmospheric turbidity, is further investigated.

Item Type: Article
Additional Information: Copyright of this article belongs to American Geophysical Union
Uncontrolled Keywords: Aerosol optical depths; Aerosol types; Arabian Sea; Atmospheric turbidity; Coarse mode particles; Desert dust; Least squares methods; Negative curvature; Pre-monsoon; Radiation budget; Second-order polynomial; Spectral band; Spectral variation, Algebra; Budget control; Turbidity, Atmospheric aerosols, aerosol composition; aerosol property; dust; integrated approach; marine atmosphere; spectral analysis; turbidity; wavelength, Arabian Sea; Indian Ocean
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 20 Feb 2015 09:10
Last Modified: 20 Feb 2015 09:10
URI: http://moeseprints.incois.gov.in/id/eprint/1726

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