Open AccessEffect of clouds on direct aerosol radiative forcing of climate
Author(s) -
Liao Hong,
Seinfeld John H.
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 - 10.1029/97jd03455
Subject(s) - aerosol , radiative forcing , atmospheric sciences , forcing (mathematics) , environmental science , cirrus , cloud forcing , soot , radiative transfer , atmosphere (unit) , meteorology , combustion , physics , chemistry , optics , organic chemistry
The effect of a cloud layer on top‐of‐atmosphere (TOA) aerosol radiative forcing is examined by means of a one‐dimensional vertical column simulation. To span the range between nonabsorbing and strongly absorbing particles, (NH 4 ) 2 SO 4 and soot aerosols are considered individually and in internal and external mixtures. For a cloud layer embedded within an aerosol layer it is shown that direct aerosol radiative forcing still occurs. For a nonabsorbing aerosol a maximum in (negative) forcing actually occurs for a thin cloud layer (100 m thickness for the set of parameters considered). The presence of an embedded cloud layer enhances the heating effect of soot aerosol, producing, for thick clouds, forcing values as much as a factor of 3 over those under cloud‐free conditions. An absorbing aerosol layer can lead to an increase of in‐cloud solar heating rates by up to 3% for the parameter values considered here. A cirrus cloud layer above an aerosol layer leads to only modest changes of TOA aerosol forcing from those in the absence of the cloud layer; thus aerosol forcing in the presence of typical cirrus clouds cannot be neglected.