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gfdl's home page > gfdl on-line bibliography > 2003: Journal of Geophysical Research, 108(D16), 4522, doi:10.1029/2002JD002966
Sensitivity of the atmospheric lapse rate to solar cloud absorption in a radiative-convective model.
| Erlick, C., and V. Ramaswamy, 2003: Sensitivity of the atmospheric lapse rate to solar cloud absorption in a radiative-convective model. Journal of Geophysical Research, 108(D16), 4522, doi:10.1029/2002JD002966. |
Abstract: Previous radiative-convective
model studies of the radiative forcing due to absorbing aerosols such as
soot and dust have revealed a strong dependence on the vertical
distribution of the absorbers. In this study, we extend this concept to
absorption in cloud layers, using a one-dimensional radiative-convective
model employing high, middle, and low cloud representations to
investigate the response of the surface temperature and atmospheric
lapse rate to increases in visible cloud absorption. The visible
single-scattering albedo (ssa) of the clouds is prescribed, ranging from
1.0 to 0.6, where 0.99 is the minimum that would be expected from the
presence of absorbing aerosols within the cloud drops on the basis of
recent Monterey Area Ship Track (MAST) Experiment case studies.
Simulations are performed with respect to both a constant cloud optical
depth and an increasing cloud optical depth and as a function of cloud
height. We find that increases in solar cloud absorption tend to warm
the troposphere and surface and stabilize the atmosphere, while
increases in cloud optical depth cool the troposphere and surface and
slightly stabilize the atmosphere between the low cloud top and surface
because of the increase in surface cooling. In the absence of
considerations involving microphysical or cloud-climate feedbacks, we
find that two conditions are required to yield an inversion from a solar
cloud absorption perturbation: (1) The solar absorption perturbation
must be included throughout the tropospheric clouds column, distributing
the solar heating to higher altitudes, and (2) the ssa of the clouds
must be  0.6,
which is an unrealistically low value. The implication is that there is
very little possibility of significant stabilization of the global mean
atmosphere due to perturbation of cloud properties given current ssa
values. |