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Aerosol optical properties and radiative forcing over mega-city Karachi

Alam, Khan and Trautmann, Thomas and Blaschke, Thomas (2011) Aerosol optical properties and radiative forcing over mega-city Karachi. Atmospheric Research, 101, pp. 773-782. Elsevier. DOI: 10.1016/j.atmosres.2011.05.007.

Full text not available from this repository.

Official URL: http://www.sciencedirect.com/science/article/pii/S0169809511001414

Abstract

Aerosol optical properties have been analyzed through the ground-based Aerosol Robotic Network (AERONET) over the mega city Karachi during August 2006 - €July 2007. The aerosol optical depth (AOD) is strongly dependent on wavelength; for shorter wavelengths AOD values are higher than at longer wavelengths. The results reveal that the monthly average AOD at 500 nm ranges from 0.31 to 0.92 with an annual mean of 0.48±0.18 and monthly averaged Angstrom exponent (Alpha) ranges from 0.17 to 1.05 with an annual mean of 0.49±0.31. The maximum monthly average AOD value of 0.92±0.28 with the corresponding Alpha value of 0.21±0.11 is found for July 2007, while the minimum monthly average AOD value of 0.31±0.11 with the corresponding Alpha value of 0.53±0.13 is recorded for March 2007. The volume size distribution in the coarse mode is higher in summer and lower in winter, whereas in the accumulation mode the volume size distribution is higher in winter than in other seasons due to the hygroscopic growth of aerosol particles. The single scattering albedo (SSA) during spring, autumn and summer seasons shows a slight increase with the wavelength and ranges from 0.88±0.02 to 0.97±0.01. The asymmetry parameter (ASY) is also wavelength dependent and varies from 0.61±0.03 to 0.74±0.02 during the year. The aerosol radiative forcing (ARF) for the whole observation period at the top of the atmosphere (TOA) is in the range of ˆ-7 to -ˆ’35 W/m^2 (average -ˆ’22±6 Wm/^2), at the surface from -ˆ’56 to -ˆ’96 W/m^2 (average -ˆ’73±12 W/m^2), increasing the atmospheric forcing from +38 to +61 W/m^2 (average +51±13 W/m^2). The SBDART-AERONET radiative forcing at the surface and TOA agree with correlation of 0.92 and 0.82, respectively.

Document Type:Article
Title:Aerosol optical properties and radiative forcing over mega-city Karachi
Authors:
AuthorsInstitution or Email of Authors
Alam, KhanDepartment of Geography and Geology, University of Salzburg, Hellbrunnerstrasse 34, Salzburg, 5020, Austria
Trautmann, Thomasthomas.trautmann@dlr.de
Blaschke, ThomasDepartment of Geography and Geology, University of Salzburg, Hellbrunnerstrasse 34, Salzburg, 5020, Austria
Date:May 2011
Journal or Publication Title:Atmospheric Research
Refereed publication:Yes
In Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:101
DOI:10.1016/j.atmosres.2011.05.007
Page Range:pp. 773-782
Publisher:Elsevier
Status:Published
Keywords:Aerosol particles, optical properties, AERONET, aerosol optical depth, Angstrom exponent, radiative forcing, megacity, Karachi
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Entwicklung von Atmosphärenprozessoren (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Remote Sensing Technology Institute > Atmospheric Processors
Deposited By: Prof.Dr. Thomas Trautmann
Deposited On:06 Feb 2012 07:43
Last Modified:21 Feb 2013 10:53

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