On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations
Otto, Sebastian and Trautmann, Thomas and Wendisch, Manfred (2011) On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations. Atmospheric Chemistry and Physics, 11, pp. 4469-4490. Copernicus Publications. DOI: 10.5194/acp-11-4469-2011.
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Official URL: http://www.atmos-chem-phys.net/11/4469/2011/
Realistic size equivalence and shape of Saharan mineral dust particles are derived from in-situ particle, lidar and sun photometer measurements during SAMUM-1 in Morocco (19 May 2006), dealing with measured size- and altitude-resolved axis ratio distributions of assumed spheroidal model particles. The data were applied in optical property, radiative effect, forcing and heating effect simulations to quantify the realistic impact of particle non-sphericity. It turned out that volume-to-surface equivalent spheroids with prolate shape are most realistic: particle non-sphericity only slightly affects single scattering albedo and asymmetry parameter but may enhance extinction coefficient by up to 10 %. At the bottom of the atmosphere (BOA) the Saharan mineral dust always leads to a loss of solar radiation, while the sign of the forcing at the top of the atmosphere (TOA) depends on surface albedo: solar cooling/warming over a mean ocean/land surface. In the thermal spectral range the dust inhibits the emission of radiation to space and warms the BOA. The most realistic case of particle non-sphericity causes changes of total (solar plus thermal) forcing by 55/5 % at the TOA over ocean/land and 15 % at the BOA over both land and ocean and enhances total radiative heating within the dust plume by up to 20 %. Large dust particles significantly contribute to all the radiative effects reported. They strongly enhance the absorbing properties and forward scattering in the solar and increase predominantly, e.g., the total TOA forcing of the dust over land.
|Title:||On realistic size equivalence and shape of spheroidal Saharan mineral dust particles applied in solar and thermal radiative transfer calculations|
|Date:||12 May 2011|
|Journal or Publication Title:||Atmospheric Chemistry and Physics|
|In Open Access:||Yes|
|In ISI Web of Science:||Yes|
|Page Range:||pp. 4469-4490|
|Keywords:||Saharan mineral dust, non-sphericity radiative effects, spheroidal particles, particle size equivalences, optical properties of mineral dust aerosols, radiative transfer, solar radiation, thermal radiation|
|HGF - Research field:||Aeronautics, Space and Transport|
|HGF - Program:||Space|
|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:||27 Jan 2012 16:02|
|Last Modified:||07 Feb 2013 20:54|
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