lmd_Boucher1998.bib
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@article{1998JCli...11.1673L,
author = {{Le Treut}, H. and {Forichon}, M. and {Boucher}, O. and {Li}, Z.-X.
},
title = {{Sulfate Aerosol Indirect Effect and CO$_{2}$ Greenhouse Forcing: EquilibriumResponse of the LMD GCM and Associated Cloud Feedbacks.}},
journal = {Journal of Climate},
year = 1998,
month = jul,
volume = 11,
pages = {1673-1684},
abstract = {{The climate sensitivity to various forcings, and in particular to
changes in CO$_{2}$ and sulfate aerosol concentrations, imposed
separately or in a combined manner, is studied with an atmospheric
general circulation model coupled to a simple slab oceanic model. The
atmospheric model includes a rather detailed treatment of warm cloud
microphysics and takes the aerosol indirect effects into account
explicitly, although in a simplified manner. The structure of the model
response appears to be organized at a global scale, with a partial
independence from the geographical structure of the forcing. Atmospheric
and surface feedbacks are likely to explain this feature. In particular
the cloud feedbacks play a very similar role in the CO$_{2}$ and
aerosol experiments, but with opposite sign. These results strengthen
the idea, already apparent from other studies, that, in spite of their
different nature and their different geographical and vertical
distributions, aerosol may have substantially counteracted the climate
effect of greenhouse gases, at least in the Northern Hemisphere, during
the twentieth century. When the effects of the two forcings are added,
the model response is not symmetric between the two hemispheres. This
feature is also consistent with the findings of other modeling groups
and has implications for the detection of future climate changes.
}},
doi = {10.1175/1520-0442(1998)011<1673:SAIEAC>2.0.CO;2},
adsurl = {http://adsabs.harvard.edu/abs/1998JCli...11.1673L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{1998TellB..50..491C,
author = {{Claquin}, T. and {Schulz}, M. and {Balkanski}, Y. and {Boucher}, O.
},
title = {{Uncertainties in assessing radiative forcing by mineral dust}},
journal = {Tellus Series B Chemical and Physical Meteorology B},
year = 1998,
month = nov,
volume = 50,
pages = {491},
abstract = {{The assessment of the climatic effects of an aerosol with a large
variability like mineral dust requires some approximations whose
validity is investigated in this paper. Calculations of direct radiative
forcing by mineral dust (short-wave, long-wave and net) are performed
with a single-column radiation model for two standard cases in clear sky
condition: a desert case and an oceanic case. Surface forcing result
from a large diminution of the short-wave fluxes and of the increase in
down-welling long-wave fluxes. Top of the atmosphere (TOA) forcing is
negative when short-wave backscattering dominates, for instance above
the ocean, and positive when short-wave or long-wave absorption
dominates, which occurs above deserts. We study here the sensitivity of
these mineral forcings to different treatments of the aerosol complex
refractive index and size distribution. We also describe the importance
of the dust vertical profile, ground temperature, emissivity and albedo.
Among these parameters, the aerosol complex refractive index has been
identified as a critical parameter given the paucity and the incertitude
associated with it. Furthermore, the imaginary part of the refractive
index is inadequate if spectrally averaged. Its natural variability
(linked to mineralogical characteristics) lead to variations of up to
{\plusmn} 40\% in aerosol forcing calculations. A proper representation of
the size distribution when modelling mineral aerosols is required since
dust optical properties are very sensitive to the presence of small
particles. In addition we demonstrate that LW forcing imply a
non-negligible sensitivity to the vertical profiles of temperature and
dust, the latter being an important constraint for dust effect
calculations.
}},
doi = {10.1034/j.1600-0889.1998.t01-2-00007.x},
adsurl = {http://adsabs.harvard.edu/abs/1998TellB..50..491C},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{1998GeoRL..25.4193D,
author = {{Doutriaux-Boucher}, M. and {Sèze}, G.},
title = {{Significant changes between the ISCCP C and D cloud climatologies}},
journal = {\grl},
keywords = {Atmospheric Composition and Structure: Cloud physics and chemistry, Global Change: Remote sensing, Meteorology and Atmospheric Dynamics: Remote sensing},
year = 1998,
volume = 25,
pages = {4193-4196},
abstract = {{ We analyse one year of cloud data from the ISCCP C and D datasets. The
two datasets differ by their retrieval algorithms and their definitions
of the cloud types defined from the cloud top pressure and cloud optical
depth. The differences between the two datasets are first described in
terms of the total cloud cover, as well as its repartition in low,
middle, and high level cloudiness. We also project the ISCCP C cloud
classes into the ISCCP D cloud types to circumvent the problem of
different cloud type definitions in the two datasets. The differences
between the two datasets are then also investigated in terms of the most
frequent cloud type.
}},
doi = {10.1029/1998GL900081},
adsurl = {http://adsabs.harvard.edu/abs/1998GeoRL..25.4193D},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{1998JGR...10326025D,
author = {{Doutriaux-Boucher}, M. and {Pelon}, J. and {Trouillet}, V. and
{SèZe}, G. and {Le Treut}, H. and {Flamant}, P. and {Desbois}, M.
},
title = {{Simulation of satellite lidar and radiometer retrievals of a general circulation model three-dimensional cloud data set}},
journal = {\jgr},
keywords = {Atmospheric Composition and Structure: Cloud physics and chemistry, Meteorology and Atmospheric Dynamics: Remote sensing, Atmospheric Composition and Structure: Instruments and techniques, Global Change: Remote sensing},
year = 1998,
month = oct,
volume = 103,
pages = {26025},
abstract = {{The inclusion of a backscatter lidar on a space platform for a radiation
mission, as proposed by various space agencies, aims to bring new
information on three-dimensional cloud distribution, with a special
emphasis on optically thin cirrus clouds, which are presently poorly
detected by passive sensors. Key issues for such cloud observational
studies are the detection of multilayered cloud systems, thin cirrus,
and fractional cloud cover, knowledge that would improve our
understanding of the global radiation budget. To assess the impact of
such lidar measurements on cloud climatology, a 1 month cloud data set
has been simulated with a general circulation model (GCM). The cloud
detection capability of a spaceborne scanning backscatter lidar is
assessed with the use of two detection schemes, one based on limitations
in the detected cloud optical depth and the other based on lidar
signal-to-noise ratio. The cloud information retrieved from passive
radiometric measurements using a procedure like that used in the
International Satellite Cloud Climatology Project is also simulated from
the same GCM cloud data set. It is shown that a spaceborne backscatter
lidar can improve significantly the retrieval of thin cirrus clouds as
well as underlying cloud layers. High-level cloud retrieval from a
spaceborne lidar therefore appears as a powerful complement to
radiometric measurements for improving our knowledge of actual cloud
climatology.
}},
doi = {10.1029/98JD02378},
adsurl = {http://adsabs.harvard.edu/abs/1998JGR...10326025D},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{1998JGR...10316979B,
author = {{Boucher}, O. and {Schwartz}, S.~E. and {Ackerman}, T.~P. and
{Anderson}, T.~L. and {Bergstrom}, B. and {Bonnel}, B. and {Ch{\'y}lek}, P. and
{Dahlback}, A. and {Fouquart}, Y. and {Fu}, Q. and {Halthore}, R.~N. and
{Haywood}, J.~M. and {Iversen}, T. and {Kato}, S. and {Kinne}, S. and
{Kirkev{\^a}G}, A. and {Knapp}, K.~R. and {Lacis}, A. and {Laszlo}, I. and
{Mishchenko}, M.~I. and {Nemesure}, S. and {Ramaswamy}, V. and
{Roberts}, D.~L. and {Russell}, P. and {Schlesinger}, M.~E. and
{Stephens}, G.~L. and {Wagener}, R. and {Wang}, M. and {Wong}, J. and
{Yang}, F.},
title = {{Intercomparison of models representing direct shortwave radiative forcing by sulfate aerosols}},
journal = {\jgr},
keywords = {Meteorology and Atmospheric Dynamics: Radiative processes, Atmospheric Composition and Structure: Aerosols and particles, Atmospheric Composition and Structure: Transmission and scattering of radiation, Global Change: Atmosphere},
year = 1998,
month = jul,
volume = 103,
pages = {16979},
abstract = {{The importance of aerosols as agents of climate change has recently been
highlighted. However, the magnitude of aerosol forcing by scattering of
shortwave radiation (direct forcing) is still very uncertain even for
the relatively well characterized sulfate aerosol. A potential source of
uncertainty is in the model representation of aerosol optical properties
and aerosol influences on radiative transfer in the atmosphere. Although
radiative transfer methods and codes have been compared in the past,
these comparisons have not focused on aerosol forcing (change in net
radiative flux at the top of the atmosphere). Here we report results of
a project involving 12 groups using 15 models to examine radiative
forcing by sulfate aerosol for a wide range of values of particle
radius, aerosol optical depth, surface albedo, and solar zenith angle.
Among the models that were employed were high and low spectral
resolution models incorporating a variety of radiative transfer
approximations as well as a line-by-line model. The normalized forcings
(forcing per sulfate column burden) obtained with the several radiative
transfer models were examined, and the discrepancies were characterized.
All models simulate forcings of comparable amplitude and exhibit a
similar dependence on input parameters. As expected for a
non-light-absorbing aerosol, forcings were negative (cooling influence)
except at high surface albedo combined with small solar zenith angle.
The relative standard deviation of the zenith-angle-averaged normalized
broadband forcing for 15 models was 8\% for particle radius near the
maximum in this forcing ({\tilde}0.2 {$\mu$}m) and at low surface albedo.
Somewhat greater model-to-model discrepancies were exhibited at specific
solar zenith angles. Still greater discrepancies were exhibited at small
particle radii, and much greater discrepancies were exhibited at high
surface albedos, at which the forcing changes sign; in these situations,
however, the normalized forcing is quite small. Discrepancies among the
models arise from inaccuracies in Mie calculations, differing treatment
of the angular scattering phase function, differing wavelength and
angular resolution, and differing treatment of multiple scattering.
These results imply the need for standardized radiative transfer methods
tailored to the direct aerosol forcing problem. However, the relatively
small spread in these results suggests that the uncertainty in forcing
arising from the treatment of radiative forcing of a well-characterized
aerosol at well-specified surface albedo is smaller than some of the
other sources of uncertainty in estimates of direct forcing by
anthropogenic sulfate aerosols and anthropogenic aerosols generally.
}},
doi = {10.1029/98JD00997},
adsurl = {http://adsabs.harvard.edu/abs/1998JGR...10316979B},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{1998JAtS...55..128B,
author = {{Boucher}, O.},
title = {{On Aerosol Direct Shortwave Forcing and the Henyey-Greenstein Phase Function.}},
journal = {Journal of Atmospheric Sciences},
year = 1998,
month = jan,
volume = 55,
pages = {128-134},
abstract = {{This technical note extends previous Mie calculations to show that there
are complex relationships between the asymmetry parameter g and the
upscatter fractions for monodirectional incident radiation
($_{0}$). Except for intermediate zenith angles and for the
upscatter fraction for diffuse radiation, there are significant
differences between ($_{0}$) predicted by the Mie theory and that
approximated by a Henyey-Greenstein phase function. While the
Henyey-Greenstein phase function is widely used in radiative transfer
calculations to characterize aerosol or cloud droplet scattering, it may
cause important discrepancies in the computation of the aerosol direct
radiative forcing, depending on solar zenith angle, aerosol size, and
refractive index. The implications of this work for aerosol and
climate-related studies are also discussed.
}},
doi = {10.1175/1520-0469(1998)055<0128:OADSFA>2.0.CO;2},
adsurl = {http://adsabs.harvard.edu/abs/1998JAtS...55..128B},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
