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.
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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 -7 to -35 W/m^2 (average -22±6 Wm/^2), at the surface from -56 to -96 W/m^2 (average -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.
|Title:||Aerosol optical properties and radiative forcing over mega-city Karachi|
|Journal or Publication Title:||Atmospheric Research|
|In Open Access:||No|
|In ISI Web of Science:||Yes|
|Page Range:||pp. 773-782|
|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)|
|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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