lmd_EMC32004.bib
@comment{{This file has been generated by bib2bib 1.95}}
@comment{{Command line: /usr/bin/bib2bib --quiet -c 'not journal:"Discussions"' -c 'not journal:"Polymer Science"' -c year=2004 -c $type="ARTICLE" -oc lmd_EMC32004.txt -ob lmd_EMC32004.bib /home/WWW/LMD/public/Publis_LMDEMC3.link.bib}}
@article{2004ClDy...23..779Q,
author = {{Quaas}, J. and {Boucher}, O. and {Dufresne}, J.-L. and {Treut}, H.
},
title = {{Impacts of greenhouse gases and aerosol direct and indirect effects on clouds and radiation in atmospheric GCM simulations of the 1930 1989 period}},
journal = {Climate Dynamics},
year = 2004,
month = dec,
volume = 23,
pages = {779-789},
abstract = {{Among anthropogenic perturbations of the Earth{\rsquo}s atmosphere,
greenhouse gases and aerosols are considered to have a major impact on
the energy budget through their impact on radiative fluxes. We use three
ensembles of simulations with the LMDZ general circulation model to
investigate the radiative impacts of five species of greenhouse gases
(CO$_{2}$, CH$_{4}$, N$_{2}$O, CFC-11 and CFC-12) and
sulfate aerosols for the period 1930 1989. Since our focus is on the
atmospheric changes in clouds and radiation from greenhouse gases and
aerosols, we prescribed sea-surface temperatures in these simulations.
Besides the direct impact on radiation through the greenhouse effect and
scattering of sunlight by aerosols, strong radiative impacts of both
perturbations through changes in cloudiness are analysed. The increase
in greenhouse gas concentration leads to a reduction of clouds at all
atmospheric levels, thus decreasing the total greenhouse effect in the
longwave spectrum and increasing absorption of solar radiation by
reduction of cloud albedo. Increasing anthropogenic aerosol burden
results in a decrease in high-level cloud cover through a cooling of the
atmosphere, and an increase in the low-level cloud cover through the
second aerosol indirect effect. The trend in low-level cloud lifetime
due to aerosols is quantified to 0.5 min day$^{-1}$
decade$^{-1}$ for the simulation period. The different
changes in high (decrease) and low-level (increase) cloudiness due to
the response of cloud processes to aerosols impact shortwave radiation
in a contrariwise manner, and the net effect is slightly positive. The
total aerosol effect including the aerosol direct and first indirect
effects remains strongly negative.
}},
doi = {10.1007/s00382-004-0475-0},
adsurl = {http://adsabs.harvard.edu/abs/2004ClDy...23..779Q},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004ClDy...22...71B,
author = {{Bony}, S. and {Dufresne}, J.-L. and {Le Treut}, H. and {Morcrette}, J.-J. and
{Senior}, C.},
title = {{On dynamic and thermodynamic components of cloud changes}},
journal = {Climate Dynamics},
year = 2004,
volume = 22,
pages = {71-86},
abstract = {{Clouds are sensitive to changes in both the large-scale circulation and
the thermodynamic structure of the atmosphere. In the tropics,
temperature changes that occur on seasonal to decadal time scales are
often associated with circulation changes. Therefore, it is difficult to
determine the part of cloud variations that results from a change in the
dynamics from the part that may result from the temperature change
itself. This study proposes a simple framework to unravel the dynamic
and non-dynamic (referred to as thermodynamic) components of the cloud
response to climate variations. It is used to analyze the contrasted
response, to a prescribed ocean warming, of the tropically-averaged
cloud radiative forcing (CRF) simulated by the ECMWF, LMD and UKMO
climate models. In each model, the dynamic component largely dominates
the CRF response at the regional scale, but this is the thermodynamic
component that explains most of the average CRF response to the imposed
perturbation. It is shown that this component strongly depends on the
behaviour of the low-level clouds that occur in regions of moderate
subsidence (e.g. in the trade wind regions). These clouds exhibit a
moderate sensitivity to temperature changes, but this is mostly their
huge statistical weight that explains their large influence on the
tropical radiation budget. Several propositions are made for assessing
the sensitivity of clouds to changes in temperature and in large-scale
motions using satellite observations and meteorological analyses on the
one hand, and mesoscale models on the other hand.
}},
doi = {10.1007/s00382-003-0369-6},
adsurl = {http://adsabs.harvard.edu/abs/2004ClDy...22...71B},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004JGRE..10912005H,
author = {{Hourdin}, F. and {Lebonnois}, S. and {Luz}, D. and {Rannou}, P.
},
title = {{Titan's stratospheric composition driven by condensation and dynamics}},
journal = {Journal of Geophysical Research (Planets)},
keywords = {Planetology: Fluid Planets: Atmospheres-structure and dynamics, Planetology: Fluid Planets: Atmospheres-composition and chemistry, Planetology: Solar System Objects: Saturnian satellites},
year = 2004,
month = dec,
volume = 109,
number = e18,
eid = {E12005},
pages = {12005},
abstract = {{Atmospheric transport of chemical compounds and organic haze in the
stratosphere of Titan is investigated with an axisymmetric general
circulation model. It has been shown previously that the meridional
circulation, dominated by global Hadley cells, is responsible both for
the creation of an intense stratospheric zonal flow and for the
accumulation of chemical compounds and haze in high latitudes. The
modified composition in turn intensifies the meridional circulation and
equator-to-pole thermal contrasts. This paper analyzes in detail the
transport processes responsible for the observed vertical and
latitudinal variations of atmospheric composition. It is shown that the
competition between rapid sinking of air from the upper stratosphere in
the winter polar vortex and latitudinal mixing by barotropic planetary
waves (parameterized in the model) controls the vertical gradient of
chemical compounds. The magnitude of polar enrichment (of a factor 1.4
to 20 depending on the particular species) with respect to low latitudes
is mostly controlled by the way the meridional advection increases the
concentrations of chemical compounds in the clean air which is rising
from the troposphere, where most of the chemical compounds are removed
by condensation (the temperature at the tropopause being close to 70 K).
The agreement between the observed and simulated contrasts provides an
indirect but strong validation of the simulated dynamics, thus
confirming the explanation put forward for atmospheric superrotation. It
is shown also that by measuring the atmospheric composition, the
Cassini-Huygens mission will provide a strong constraint about Titan's
atmospheric circulation.
}},
doi = {10.1029/2004JE002282},
adsurl = {http://adsabs.harvard.edu/abs/2004JGRE..10912005H},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004AnGeo..22.4043C,
author = {{Chèruy}, F. and {Speranza}, A. and {Sutera}, A. and {Tartaglione}, N.
},
title = {{Surface winds in the Euro-Mediterranean area: the real resolution of numerical grids}},
journal = {Annales Geophysicae},
year = 2004,
month = dec,
volume = 22,
pages = {4043-4048},
abstract = {{Surface wind is a variable of great importance in forcing marine waves
and circulations, modulating surface fluxes, etc. Surface wind defined
on numerical grids is currently used in forecast-analysis, as well as in
climatology. Gridded fields, however, suffer for systematic errors
associated with the numerical procedures adopted in computing them. In
this paper the climatology of surface wind produced by three different
numerical models in the European-Mediterranean area is analyzed. The
systematic loss of power at the smallest grid-scales appears in the
power spectrum of all the different models. Some prototype numerical
integrations show that this systematic over-smoothing is due to
numerical stabilization operators that represent the main source of the
diagnosed error; the error progression in space and time is also
analyzed.
}},
doi = {10.5194/angeo-22-4043-2004},
adsurl = {http://adsabs.harvard.edu/abs/2004AnGeo..22.4043C},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004AtmRe..72..239E,
author = {{Eymet}, V. and {Dufresne}, J.~L. and {Ricchiazzi}, P. and {Fournier}, R. and
{Blanco}, S.},
title = {{Long-wave radiative analysis of cloudy scattering atmospheres using a net exchange formulation}},
journal = {Atmospheric Research},
year = 2004,
month = nov,
volume = 72,
pages = {239-261},
abstract = {{The Net Exchange Formulation (NEF) is an alternative to the usual
radiative transfer equation. It was proposed in 1967 by Green [Q. J. R.
Meteorol. Soc. 93 (1967) 371] for atmospheric sciences and by Hottel
[H.C. Hottel, A.F. Sarofim. Radiative Transfer McGraw Hill, New York,
1967] for engineering sciences. Until now, the NEF has been used only in
a very few cases for atmospheric studies. Recently we have developed a
long-wave radiative code based on this formulation for a GCM of the Mars
planet. Here, we will present results for the Earth atmosphere, obtained
with a Monte Carlo Method based on the NEF. In this method, fluxes are
not addressed any more. The basic variables are the net exchange rates
(NER) between each pair of atmospheric layer ( i, j), i.e. the radiative
power emitted by i and absorbed by j minus the radiative power emitted
by j and absorbed by i. The graphical representation of the NER matrix
highlights the radiative exchanges that dominate the radiative budget of
the atmosphere and allows one to have a very good insight of the
radiative exchanges. Results will be presented for clear sky atmospheres
with Mid-Latitude Summer and Sub-Arctic Winter temperature profiles, and
for the same atmospheres with three different types of clouds. The
effect of scattering on long-wave radiative exchanges will also be
analysed.
}},
doi = {10.1016/j.atmosres.2004.03.017},
adsurl = {http://adsabs.harvard.edu/abs/2004AtmRe..72..239E},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004QJRMS.130.3223T,
author = {{Tailleux}, R. and {Grandpeix}, J.~Y.},
title = {{On the seemingly incompatible parcel and globally integrated views of the energetics of triggered atmospheric deep convection over land}},
journal = {Quarterly Journal of the Royal Meteorological Society},
keywords = {CONVECTIVE AVAILABLE POTENTIAL ENERGY, CONVECTIVE INHIBITION ENERGY, ENERGY CYCLE, MULTIPLE REFERENCE STATES},
year = 2004,
month = oct,
volume = 130,
pages = {3223-3243},
abstract = {{The energetics of the diurnal cycle of atmospheric deep convection over
land remain difficult to understand and simulate accurately with current
cumulus parametrizations. Furthermore, a proper formulation has remained
elusive owing to seeming incompatibilities between, on the one hand, the
parcel view of energetics which relies on such concepts as Convective
Available Potential Energy (CAPE) and Convective Inhibition (CIN), and,
on the other hand, the globally integrated view, which relies on such
concepts as Moist Available Energy (MAE), reference states, and energy
conversion terms. While the MAE is intuitively the global counterpart of
the parcel-defined CAPE, there seems to be no global analogue to the
parcel-defined concept of energy barrier attached to CIN. To gain
insights into this issue, a new cost function PE is introduced to
quantify the amount of positive or negative energy required for a given
sounding to undergo an arbitrary adiabatic rearrangement of mass, and
which encompasses both the parcel-defined and global energy concepts as
particular cases. The function PE offers a complementary view of the
stability and energy characteristics of atmospheric soundings, whose
local minima are naturally associated with the reference states of the
system. It is established that: (a) MAE is essentially equivalent to
CAPE multiplied by a mass conversion factor Mb which scales as the
amount of convectively unstable boundary-layer air. Using the available
summer 1997 IOP data from the ARM- SGP site, Mb is found to correlate
with CAPE, which suggests the existence of a functional relationship
between CAPE and MAE; if further confirmed, this result would
considerably simplify the computation of MAE. (b) A global counterpart
to the parcel-defined concept of energy barrier can only be defined if
the system considered admits several reference states, and not one as is
classically assumed. In that case, energy barriers naturally arise as
the amount of energy required to switch from one reference state to
another. In the context of triggered deep convection, there must be at
least two reference states: a shallow one, which is the actual state (or
a slightly modified one if there is boundary layer CAPE), and a deep one
associated with the release of MAE/CAPE; the energy barrier separating
these two reference states naturally defines a generalized CIN. In the
limited context of the above-mentioned IOP ARM data, it is further shown
that: (c) Spatially averaged conditions exhibiting potential instability
to deep convection may be associated with individual soundings having
widely different stability characteristics, including absolute
stability, potential instability, and absolute instability; this
suggests that triggered deep convection may not necessarily be the
result of a parcel's vertical kinetic energy exceeding its negative
buoyancy, but rather from the destruction of convective inhibition (i.e.
production of absolute instability) in a local region. (d) A few local
soundings exhibit multiple reference states, corresponding roughly to
multiple levels of neutral buoyancy. These may allow for convective
clouds with cloud-top heights significantly lower than those classically
predicted by the undiluted ascent of a boundary-layer air parcel up to
its highest level of neutral buoyancy, even in the absence of complex
entrainment scenarios.
}},
doi = {10.1256/qj.03.140},
adsurl = {http://adsabs.harvard.edu/abs/2004QJRMS.130.3223T},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004QJRMS.130.3207G,
author = {{Grandpeix}, J.~Y. and {Phillips}, V. and {Tailleux}, R.},
title = {{Improved mixing representation in Emanuel's convection scheme}},
journal = {Quarterly Journal of the Royal Meteorological Society},
keywords = {CUMULUS PARAMETRIZATION, ENTRAINMENT, MIXING, TROPOSPHERIC HUMIDITY},
year = 2004,
month = oct,
volume = 130,
pages = {3207-3222},
abstract = {{Recent empirical and modelling studies suggest that mid-tropospheric
relative humidity (RH) is an important controlling factor of deep
atmospheric convection, which appears to be underestimated in present
cumulus parametrizations. This indicates the possible presence of
shortcomings in the way that entrainment is represented in such
parametrizations. This matter was explored in the European Cloud Systems
project (EUROCS) by means of an idealized humidity experiment in which
the main controlling parameter is RH. In the latter study,
cloud-resolving model (CRM) experiments suggested that a shallow/deep
convection transition occurs when RH crosses a threshold value that
ranges from about RH = 50\% to RH = 60\%. In this paper, we seek to
increase the responsiveness of Emanuel's convection scheme to RH, and to
reproduce the threshold behaviour of the idealized humidity case, by
replacing the original uniform probability density function (PDF) for
mixing fractions by a more flexible two-parameter bell-shaped function
that allows a wider range of behaviour. The main result is that the
parameters of this PDF can be tuned to allow a regime transition to
occur near a threshold value of RH 55\%. In contrast to CRM results,
however, this transition is between two different regimes of deep
convection rather than between a shallow and deep regime. Possible ways
to obtain a shallow-to-deep transition with Emanuel's scheme are
discussed.
}},
doi = {10.1256/qj.03.144},
adsurl = {http://adsabs.harvard.edu/abs/2004QJRMS.130.3207G},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004QJRMS.130.3055D,
author = {{Derbyshire}, S.~H. and {Beau}, I. and {Bechtold}, P. and {Grandpeix}, J.-Y. and
{Piriou}, J.-M. and {Redelsperger}, J.~L. and {Soares}, P.~M.~M.
},
title = {{Sensitivity of moist convection to environmental humidity}},
journal = {Quarterly Journal of the Royal Meteorological Society},
keywords = {CUMULUS CONVECTION, HUMIDITY SENSITIVITY, MODEL INTERCOMPARISON},
year = 2004,
month = oct,
volume = 130,
pages = {3055-3079},
abstract = {{As part of the EUROCS (EUROpean Cloud Systems study) project,
cloud-resolving model (CRM) simulations and parallel single-column model
(SCM) tests of the sensitivity of moist atmospheric convection to
mid-tropospheric humidity are presented. This sensitivity is broadly
supported by observations and some previous model studies, but is still
poorly quantified. Mixing between clouds and environment is a key
mechanism, central to many of the fundamental differences between
convection schemes. Here, we define an idealized quasi-steady 'testbed',
in which the large-scale environment is assumed to adjust the local mean
profiles on a timescale of one hour. We then test sensitivity to the
target profiles at heights above 2 km. Two independent CRMs agree
reasonably well in their response to the different background profiles
and both show strong deep precipitating convection in the more moist
cases, but only shallow convection in the driest case. The CRM results
also appear to be numerically robust. All the SCMs, most of which are
one-dimensional versions of global climate models (GCMs), show
sensitivity to humidity but differ in various ways from the CRMs. Some
of the SCMs are improved in the light of these comparisons, with GCM
improvements documented elsewhere.
}},
doi = {10.1256/qj.03.130},
adsurl = {http://adsabs.harvard.edu/abs/2004QJRMS.130.3055D},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004JGRD..10920112B,
author = {{Bonazzola}, M. and {Haynes}, P.~H.},
title = {{A trajectory-based study of the tropical tropopause region}},
journal = {Journal of Geophysical Research (Atmospheres)},
keywords = {Meteorology and Atmospheric Dynamics: Stratosphere/troposphere interactions, Meteorology and Atmospheric Dynamics: Tropical meteorology, Global Change: Water cycles (1836), Global Change: Climate dynamics (3309), tropical tropopause, stratospheric water vapor, El Ni{\~n}o, tropical dehydration},
year = 2004,
month = oct,
volume = 109,
number = d18,
eid = {D20112},
pages = {20112},
abstract = {{Large ensembles of 90-day backward trajectory calculations from the
tropical lower stratosphere are performed for Northern Hemisphere (NH)
winters 1997-1998 and 1998-1999 and summer 1999 on the basis of European
Center for Medium-Range Weather Forecasts operational analysis data. The
calculated trajectories are analyzed to determine patterns of transport
and encountered temperatures and implications for lower stratospheric
water vapor. For each set of back-trajectories, a
troposphere-to-stratosphere (TS) ensemble, originating below 355 K, is
identified. Trajectories in the TS ensemble sample the coldest regions
of the tropical tropopause region very efficiently. Corresponding water
vapor concentrations are calculated using two simple dehydration models,
one (model 1) assuming instantaneous dehydration and the other (model 2)
taking some account of time delays associated with microphysical
processes. Model 1 predicts average concentrations for the TS ensembles
of 1.5 and 2.0 ppmv in the two NH winters and 3.8 ppmv in NH summer.
Model 2 predicts concentrations that are about 0.5 ppmv larger. The
effect of temperature variability along the trajectories is considered
and is shown to arise primarily through horizontal advection through
strong gradients rather than through temporal variability. A
quantitative method is described to assess the efficiency of sampling of
cold regions, the roles played by different transport processes, and
differences between seasons or years. Both vertical transport (the
''stratospheric fountain'' effect) and horizontal transport are shown to
play important roles in dehydration, with the former more important in
NH winter and the latter more important in NH summer. Differences in
predicted water vapor between NH winter 1997-1998 (El Ni{\~n}o) and
1998-1999 (La Ni{\~n}a) are due to the warmer region of coldest
temperatures in 1997-1998 than in 1998-1999 and to the less efficient
sampling of cold temperatures by both horizontal and vertical
circulations during the former.
}},
doi = {10.1029/2003JD004356},
adsurl = {http://adsabs.harvard.edu/abs/2004JGRD..10920112B},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004JGRD..10916205R,
author = {{Reddy}, M.~S. and {Boucher}, O. and {Venkataraman}, C. and
{Verma}, S. and {LéOn}, J.-F. and {Bellouin}, N. and {Pham}, M.
},
title = {{General circulation model estimates of aerosol transport and radiative forcing during the Indian Ocean Experiment}},
journal = {Journal of Geophysical Research (Atmospheres)},
keywords = {Atmospheric Composition and Structure: Aerosols and particles (0345, 4801), Atmospheric Composition and Structure: Troposphere-constituent transport and chemistry, Atmospheric Composition and Structure: Pollution-urban and regional (0305), Atmospheric Composition and Structure: Transmission and scattering of radiation, Indian Ocean, India, south Asia, radiative impacts, fly ash},
year = 2004,
month = aug,
volume = 109,
number = d18,
eid = {D16205},
pages = {16205},
abstract = {{Aerosol sources, transport, and sinks are simulated, and aerosol direct
radiative effects are assessed over the Indian Ocean for the Indian
Ocean Experiment (INDOEX) Intensive Field Phase during January to March
1999 using the Laboratoire de Météorologie Dynamique
(LMDZT) general circulation model. The model reproduces the latitudinal
gradient in aerosol mass concentration and optical depth (AOD). The
model-predicted aerosol concentrations and AODs agree reasonably well
with measurements but are systematically underestimated during
high-pollution episodes, especially in the month of March. The largest
aerosol loads are found over southwestern China, the Bay of Bengal, and
the Indian subcontinent. Aerosol emissions from the Indian subcontinent
are transported into the Indian Ocean through either the west coast or
the east coast of India. Over the INDOEX region, carbonaceous aerosols
are the largest contributor to the estimated AOD, followed by sulfate,
dust, sea salt, and fly ash. During the northeast winter monsoon,
natural and anthropogenic aerosols reduce the solar flux reaching the
surface by 25 W m$^{-2}$, leading to 10-15\% less insolation at the
surface. A doubling of black carbon (BC) emissions from Asia results in
an aerosol single-scattering albedo that is much smaller than in situ
measurements, reflecting the fact that BC emissions are not
underestimated in proportion to other (mostly scattering) aerosol types.
South Asia is the dominant contributor to sulfate aerosols over the
INDOEX region and accounts for 60-70\% of the AOD by sulfate. It is also
an important but not the dominant contributor to carbonaceous aerosols
over the INDOEX region with a contribution of less than 40\% to the AOD
by this aerosol species. The presence of elevated plumes brings
significant quantities of aerosols to the Indian Ocean that are
generated over Africa and Southeast and east Asia.
}},
doi = {10.1029/2004JD004557},
adsurl = {http://adsabs.harvard.edu/abs/2004JGRD..10916205R},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004Icar..170..443R,
author = {{Rannou}, P. and {Hourdin}, F. and {McKay}, C.~P. and {Luz}, D.
},
title = {{A coupled dynamics-microphysics model of Titan's atmosphere}},
journal = {\icarus},
year = 2004,
month = aug,
volume = 170,
pages = {443-462},
abstract = {{We have developed a coupled general circulation model of Titan's
atmosphere in which the aerosol haze is treated with a microphysical
model and is advected by the winds. The radiative transfer accounts for
the non uniform haze distribution and, in turn, drives the dynamics. We
analyze the GCM results, especially focusing on the difference between a
uniform haze layer and a haze layer coupled to the dynamics. In the
coupled simulation the aerosols tend to accumulate at the poles, at
latitudes higher than {\plusmn}60{\deg}. During winter, aerosols strongly
radiate at thermal infrared wavelengths enhancing the cooling rate near
the pole. Since this tends to increase the latitudinal gradients of
temperature the direct effect of this cooling excess, in contrast to the
uncoupled haze case, is to increase the strength of the meridional cells
as well as the strength of the zonal winds and profile. This is a
positive feedback of the haze on dynamics. The coupled model reproduces
observations about the state of the atmosphere better than the uniform
haze model, and in addition, the northern polar hood and the detached
haze are qualitatively reproduced.
}},
doi = {10.1016/j.icarus.2004.03.007},
adsurl = {http://adsabs.harvard.edu/abs/2004Icar..170..443R},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004QJRMS.130.2217B,
author = {{Bellouin}, N. and {Boucher}, O. and {Vesperini}, M. and {Tanré}, D.~E.
},
title = {{Estimating the direct aerosol radiative perturbation: Impact of ocean surface representation and aerosol non-sphericity}},
journal = {Quarterly Journal of the Royal Meteorological Society},
keywords = {BRDF, RADIATIVE TRANSFER, SAHARAN DUST},
year = 2004,
month = jul,
volume = 130,
pages = {2217-2232},
abstract = {{Atmospheric aerosols are now actively studied, in particular because of
their radiative and climate impacts. Estimations of the direct aerosol
radiative perturbation, caused by extinction of incident solar
radiation, usually rely on radiative transfer codes and involve
simplifying hypotheses. This paper addresses two approximations which
are widely used for the sake of simplicity and limiting the
computational cost of the calculations. Firstly, it is shown that using
a Lambertian albedo instead of the more rigorous bidirectional
reflectance distribution function (BRDF) to model the ocean surface
radiative properties leads to large relative errors in the instantaneous
aerosol radiative perturbation. When averaging over the day, these
errors cancel out to acceptable levels of less than 3\% (except in the
northern hemisphere winter). The other scope of this study is to address
aerosol non-sphericity effects. Comparing an experimental phase function
with an equivalent Mie-calculated phase function, we found acceptable
relative errors if the aerosol radiative perturbation calculated for a
given optical thickness is daily averaged. However, retrieval of the
optical thickness of non-spherical aerosols assuming spherical particles
can lead to significant errors. This is due to significant differences
between the spherical and non-spherical phase functions. Discrepancies
in aerosol radiative perturbation between the spherical and
non-spherical cases are sometimes reduced and sometimes enhanced if the
aerosol optical thickness for the spherical case is adjusted to fit the
simulated radiance of the non-spherical case.
}},
doi = {10.1256/qj.03.136},
adsurl = {http://adsabs.harvard.edu/abs/2004QJRMS.130.2217B},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004JGRD..10914202R,
author = {{Reddy}, M.~S. and {Boucher}, O.},
title = {{A study of the global cycle of carbonaceous aerosols in the LMDZT general circulation model}},
journal = {Journal of Geophysical Research (Atmospheres)},
keywords = {Atmospheric Composition and Structure: Aerosols and particles (0345, 4801), Atmospheric Composition and Structure: Pollution-urban and regional (0305), Atmospheric Composition and Structure: Troposphere-composition and chemistry, carbonaceous aerosols, model validation, sensitivity studies},
year = 2004,
month = jul,
volume = 109,
number = d18,
eid = {D14202},
pages = {14202},
abstract = {{The global atmospheric cycle of carbonaceous aerosols is simulated in
the Laboratoire de Météorologie Dynamique general
circulation model, and the subsequent aerosol optical depth is estimated
for the period 1997 to 1999. The seasonal and interannual variability in
the open biomass burning emissions has been improved by combining
existing emission inventories and satellite measured fire counts. The
model performance has been thoroughly evaluated against measured aerosol
mass concentrations and optical depth in different regions of the globe.
At a majority of locations, the modeled mass concentrations of black
carbon (BC) at the surface are within a factor of two of observed
values. The concentrations of organic carbon (OC) are generally
underestimated in comparison to measurements. The discrepancies between
model predicted values and measurements are attributable to the
difference in time periods between the measurements and model
simulations and/or a real underestimation of aerosol emissions in the
model. The atmospheric residence times of both BC and OC aerosols are
about a week. The hydrophilic fraction of carbonaceous aerosols accounts
for about 90\% of the total burden. Organic matter (OM) and associated
water dominate the optical depth by carbonaceous aerosols with a 86\%
contribution (global mean of 0.031 at 0.55 {$\mu$}m). Different sensitivity
experiments on the transformation time for conversion of hydrophobic to
hydrophilic aerosols and emission partitioning show significant changes
in the distribution of aerosol burdens and optical depth. The globally
averaged burdens change by {\plusmn}15\% and residence times are shorter
or longer by about 1 day in the various experiments as compared to the
control simulation. In all of these experiments the largest sensitivity
in aerosol concentrations is found in the remote regions and in the free
troposphere (pressure range of 700-400 hPa). Emissions from biomass
burning dominate the burden and optical depth of carbonaceous aerosols
in the entire SH and NH tropics, while fossil fuel emissions dominate
the NH extratropics. On the global scale biomass burning accounts for
78\% of the total carbonaceous aerosol burden (BC + OM) followed by
natural secondary organic aerosols (SOA)(14\%) and fossil fuels (8\%). The
contributions to corresponding AOD are similar with the largest
contribution from biomass burning (76\%) followed by natural SOA (14\%),
and fossil fuels (10\%).
}},
doi = {10.1029/2003JD004048},
adsurl = {http://adsabs.harvard.edu/abs/2004JGRD..10914202R},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004JGRD..109.8205Q,
author = {{Quaas}, J. and {Boucher}, O. and {BréOn}, F.-M.},
title = {{Aerosol indirect effects in POLDER satellite data and the Laboratoire de Météorologie Dynamique-Zoom (LMDZ) general circulation model}},
journal = {Journal of Geophysical Research (Atmospheres)},
keywords = {Atmospheric Composition and Structure: Cloud physics and chemistry, Atmospheric Composition and Structure: Aerosols and particles (0345, 4801), Global Change: Atmosphere (0315, 0325), Global Change: Remote sensing, Hydrology: Anthropogenic effects, indirect effects, aerosol, clouds},
year = 2004,
month = apr,
volume = 109,
eid = {D08205},
pages = {8205},
abstract = {{The POLDER-1 instrument was able to measure aerosol and cloud properties
for eight months in 1996-1997. We use these observational data for
aerosol concentration (the aerosol index), cloud optical thickness, and
cloud droplet effective radius to establish statistical relationships
among these parameters in order to analyze the first and second aerosol
indirect effects. We also evaluate the representation of these effects
as parameterized in the Laboratoire de Météorologie
Dynamique-Zoom (LMDZ) general circulation model. We find a decrease in
cloud top droplet radius with increasing aerosol index in both the model
and the observations. Our results are only slightly changed if the
analysis is done at fixed cloud liquid water path (LWP) instead of
considering all LWP conditions. We also find a positive correlation
between aerosol index and cloud liquid water path, which is particularly
pronounced over the Northern Hemisphere midlatitudes. This may be
interpreted as observational evidence for the second aerosol indirect
effect on a large scale. The model-simulated relationship agrees well
with that derived from POLDER data. Model simulations show a rather
small change in the two relationships if preindustrial rather than
present-day aerosol distributions are used. However, when entirely
switching off the second aerosol indirect effect in our model, we find a
much steeper slope than we do when including it.
}},
doi = {10.1029/2003JD004317},
adsurl = {http://adsabs.harvard.edu/abs/2004JGRD..109.8205Q},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004E&PSL.220..409L;,
author = {{Li}, Z.~X. and {Evans}, D.~A.~D. and {Zhang}, S.},
title = {{A 90{\deg} spin on Rodinia: possible causal links between the Neoproterozoic supercontinent, superplume, true polar wander and low-latitude glaciation}},
journal = {Earth and Planetary Science Letters},
keywords = {Rodinia, supercontinent, Neoproterozoic, paleomagnetism, South China, superplume, true polar wander},
year = 2004,
month = apr,
volume = 220,
pages = {409-421},
abstract = {{We report here new geochronological and paleomagnetic data from the
802{\plusmn}10 Ma Xiaofeng dykes in South China. Together with existing
data, these results suggest that Rodinia probably spread from the
equator to the polar region at ca. 800 Ma, followed by a rapid ca.
90{\deg} rotation around an axis near Greenland that brought the entire
supercontinent to a low-latitude position by ca. 750 Ma. We propose that
it was the initiation of a mantle superplume under the polar end of
Rodinia that triggered an episode of true polar wander (TPW) which
brought the entire supercontinent into equatorial latitudes. An
unusually extensive emerged land area at the equator increased both
atmospheric CO $_{2}$ drawdown and global albedo, which, along
with waning plume volcanism led directly to the low-latitude Sturtian
glaciation at ca. 750-720 Ma.
}},
doi = {10.1016/S0012-821X(04)00064-0},
adsurl = {http://adsabs.harvard.edu/abs/2004E%26PSL.220..409L},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004JGRD..109.4314H,
author = {{Hauglustaine}, D.~A. and {Hourdin}, F. and {Jourdain}, L. and
{Filiberti}, M.-A. and {Walters}, S. and {Lamarque}, J.-F. and
{Holland}, E.~A.},
title = {{Interactive chemistry in the Laboratoire de Météorologie Dynamique general circulation model: Description and background tropospheric chemistry evaluation}},
journal = {Journal of Geophysical Research (Atmospheres)},
keywords = {Atmospheric Composition and Structure: Constituent sources and sinks, Atmospheric Composition and Structure: Troposphere-composition and chemistry, Atmospheric Composition and Structure: Troposphere-constituent transport and chemistry, global modeling, tropospheric ozone budget, climate-chemistry interactions},
year = 2004,
month = feb,
volume = 109,
eid = {D04314},
pages = {4314},
abstract = {{We provide a description and evaluation of LMDz-INCA, which couples the
Laboratoire de Météorologie Dynamique general circulation
model (LMDz) and the Interaction with Chemistry and Aerosols (INCA)
model. In this first version of the model a
CH$_{4}$-NO$_{x}$-CO-O$_{3}$ chemical scheme
representative of the background chemistry of the troposphere is
considered. We derive rapid interhemispheric exchange times of 1.13-1.38
years and 0.70-0.82 years, based on surface and pressure-weighted mixing
ratios of inert tracers, respectively. The general patterns of the
nitrogen deposition are correctly reproduced by the model. However,
scavenging processes remain a major source of uncertainty in current
models, with convective precipitation playing a key role in the global
distribution of soluble species. The global and annual mean methane (7.9
years) and methylchloroform (4.6 years) chemical lifetimes suggest that
OH is too high by about 19-25\% in the model. This disagreement with
previous estimates is attributed to the missing nonmethane hydrocarbons
in this version of the model. The model simulates quite satisfactorily
the distribution and seasonal cycle of CO at most stations. At several
tropical sites and in the Northern Hemisphere during summer, the OH
overestimate leads, however, to a too intense CO chemical destruction.
LMDz-INCA reproduces fairly well the distribution of ozone throughout
most of the troposphere. A main disagreement appears in the Northern
Hemisphere upper troposphere during summer, due to a too high tropopause
in the GCM. When the GCM winds are relaxed toward assimilated
meteorology, a much higher variability is obtained for ozone in the
upper troposphere, reflecting more frequent stratospheric intrusions.
The stratospheric influx of ozone increases from 523 Tg/yr in the base
case simulation to 783 Tg/yr in the nudged version.
}},
doi = {10.1029/2003JD003957},
adsurl = {http://adsabs.harvard.edu/abs/2004JGRD..109.4314H},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004GeoRL..31.3103M,
author = {{Mahowald}, N.~M. and {Dufresne}, J.-L.},
title = {{Sensitivity of TOMS aerosol index to boundary layer height: Implications for detection of mineral aerosol sources}},
journal = {\grl},
keywords = {Atmospheric Composition and Structure: Aerosols and particles (0345, 4801), Atmospheric Composition and Structure: Biosphere/atmosphere interactions, Global Change: Atmosphere (0315, 0325), Global Change: Biogeochemical processes (4805), Atmospheric Composition and Structure: Troposphere-composition and chemistry},
year = 2004,
month = feb,
volume = 31,
eid = {L03103},
pages = {3103},
abstract = {{The TOMS aerosol index (AI) is proposed as a powerful tool in
determining the sources of mineral aerosols. The sensitivity of the AI
to the height of the aerosol layer has been noted previously, but the
implications of this sensitivity for deducing sources has not been
explicitly considered. Here, we present a methodology and sensitivity
test to show the importance of spatial and temporal variations of the
planetary boundary layer height to deducing sources using the AI. These
results suggest that while dry topographic low sources may be large
sources of desert dust, conclusions eliminating other sources may be
premature, especially when these sources occur on the edges of deserts,
where boundary layer heights are lower, and human influences potentially
more important. The compounding problem of differentiating downwind
transport and local sources suggests it may not currently be possible to
use the AI to conclusively determine mineral aerosol source regions.
}},
doi = {10.1029/2003GL018865},
adsurl = {http://adsabs.harvard.edu/abs/2004GeoRL..31.3103M},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004AdSpR..33.1080P,
author = {{Parol}, F. and {Buriez}, J.~C. and {Vanbauce}, C. and {Riedi}, J. and
{Labonnote}, L.~C. and {Doutriaux-Boucher}, M. and {Vesperini}, M. and
{Sèze}, G. and {Couvert}, P. and {Viollier}, M. and {Bréon}, F.~M.
},
title = {{Review of capabilities of multi-angle and polarization cloud measurements from POLDER}},
journal = {Advances in Space Research},
year = 2004,
month = jan,
volume = 33,
pages = {1080-1088},
abstract = {{Polarization and directionality of the Earth's reflectances (POLDER) is
a multispectral imaging radiometer-polarimeter with a wide
field-of-view, a moderate spatial resolution, and a multi-angle viewing
capability. It functioned nominally aboard ADEOS1 from November 1996 to
June 1997. When the satellite passes over a target, POLDER allows to
observe it under up to 14 different viewing directions and in several
narrow spectral bands of the visible and near-infrared spectrum (443-910
nm). This new type of multi-angle instruments offers new opportunity for
deriving cloud parameters at global scale. The aim of this short
overview paper is to point out the main contributions of such an
instrument for cloud study through its original instrumental
capabilities (multidirectionality, multipolarization, and
multispectrality). This is mainly illustrated by using ADEOS 1-POLDER
derived cloud parameters which are operationally processed by CNES and
are available since the beginning of 1999.
}},
doi = {10.1016/S0273-1177(03)00734-8},
adsurl = {http://adsabs.harvard.edu/abs/2004AdSpR..33.1080P},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
@article{2004ClDy...22..597B,
author = {{Boucher}, O. and {Myhre}, G. and {Myhre}, A.},
title = {{Direct human influence of irrigation on atmospheric water vapour and climate}},
journal = {Climate Dynamics},
year = 2004,
volume = 22,
pages = {597-603},
abstract = {{Human activity increases the atmospheric water vapour content in an
indirect way through climate feedbacks. We conclude here that human
activity also has a direct influence on the water vapour concentration
through irrigation. In idealised simulations we estimate a global mean
radiative forcing in the range of 0.03 to +0.1 Wm$^{-2}$ due to
the increase in water vapour from irrigation. However, because the water
cycle is embodied in the climate system, irrigation has a more complex
influence on climate. We also simulate a change in the temperature
vertical profile and a large surface cooling of up to 0.8 K over
irrigated land areas. This is of opposite sign than expected from the
radiative forcing alone, and this questions the applicability of the
radiative forcing concept for such a climatic perturbation. Further,
this study shows stronger links than previously recognised between
climate change and freshwater scarcity which are environmental issues of
paramount importance for the twenty first century.
}},
doi = {10.1007/s00382-004-0402-4},
adsurl = {http://adsabs.harvard.edu/abs/2004ClDy...22..597B},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}
