Open AccessModeling the radiative characteristics of airborne mineral aerosols at infrared wavelengths
Author(s) -
Sokolik Iri.,
Toon Owen B.,
Bergstrom Robert W.
Publication year - 1998
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/98jd00049
Subject(s) - mineral dust , radiative forcing , aerosol , radiative transfer , atmosphere (unit) , atmospheric sciences , environmental science , forcing (mathematics) , earth's energy budget , radiative flux , flux (metallurgy) , wavelength , infrared , radiation , materials science , meteorology , geology , physics , optics , metallurgy
We explore the importance of the composition of airborne mineral aerosols for assessments of their direct radiative forcing at infrared wavelengths. Our calculations employing Mie theory and data on spectral refractive indices show that the existing variations in refractive indices can cause large changes in the major aerosol optical characteristics. Calculations of IR radiative forcings at the top of the atmosphere and IR downward and upward fluxes, based on an one‐dimensional radiation transfer code, give a wide range of results for varying optical models of the mineral aerosols. We estimate that for a “low dust loading” scenario the changes in IR downward flux at the surface relative to dust free conditions are in the range from 7 to 14 W/m 2 depending upon the mineral aerosol selected. Under “dry tropics” atmospheric conditions the IR forcing at the top of the atmosphere is in the range from 2 to 7 W/m 2 . In turn, for a “high dust loading” scenario the calculated changes, relative to dust free conditions, in IR downward flux at the surface vary from 50 to 80 W/m 2 , and the IR forcing at the top of the atmosphere varies from 15 to 25 W/m 2 . Therefore, we conclude that incorporation of regionally and temporally varying dust mineralogical composition into general circulation models could be beneficial for decreasing the currently large uncertainties in the assessment of radiative forcing by the natural and anthropogenic components of the airborne mineral aerosols. Also the use of appropriate mineralogical data is required for remote sensing of the atmospheric aerosols using satellite infrared observations.