Sensitivities of the radiative forcing due to large loadings of smoke and dust aerosols
Sensitivities of the optical properties and of the radiative perturbations induced by the microphysical characteristics of smoke and dust aerosols in the aftermath of a nuclear war are investigated. All optical calculations assume homogeneous spherical particles, prescribed by lognormal size distributions. A change in the mode radius of the aerosol size distribution between 0.1 and 1.0 ..mu..m, for a constant smoke loading, results in a tenfold decrease in the visible optical depth. Over the same size range the long-wave optical depth increases from 1/30 of the visible optical depth for a mode radius of 0.1 ..mu..m to 1/2 for a mode radius of 1.0 ..mu..m. The direct radiative forcing is studied using a spectrally dependent, one-dimensional radiative transfer model. The radiative heating is strongly influenced by the vertical distribution of smoke and dust aerosols. When compared with a constant density profile, the maximum in the heating rate, owing to a 3-km, scale height profile of smoke aerosols (visible optical depth approx.3), is reduced from 16/sup 0/ to 4/sup 0/ K/d and is more widely distributed in the troposphere. Solar absorption in the troposphere is reduced by increases in dust loadings in the stratosphere (a loading of 0.5 g/m/sup 2/ results in a 30% reduction), while the planetary albedo is enhanced over the smoke-only case (up to 150% for 0.5 g/m/sup 2/). Perturbations to the long-wave fluxes due to aerosols are modulated by the column amount of water vapor. The increase in the long-wave flux at the surface, however, even for an order of magnitude enhancement in water vapor, is less than the decrease in the solar flux.
- Research Organization:
- National Center for Atmospheric Research, Boulder, Colorado
- OSTI ID:
- 5562271
- Journal Information:
- J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 90:D3; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AEROSOLS
COLLOIDS
DISPERSIONS
DUSTS
EARTH ATMOSPHERE
ELECTROMAGNETIC RADIATION
EMISSIVITY
ENERGY TRANSFER
EXPLOSIONS
HEAT TRANSFER
NUCLEAR EXPLOSIONS
ONE-DIMENSIONAL CALCULATIONS
OPACITY
OPTICAL PROPERTIES
PARTICLE SIZE
PARTICLES
PARTICULATES
PHYSICAL PROPERTIES
RADIANT HEAT TRANSFER
RADIATIONS
RESIDUES
SENSITIVITY ANALYSIS
SIZE
SMOKES
SOLAR FLUX
SOLS
SURFACE PROPERTIES
THERMAL RADIATION