(EUROpean
Cloud Systems)
Project
Funded by the European Community
Objectives
Project
Outline
Project
Participants
Project
Coordinators
Case
Studies
Pacific
Intercomparison Case for 3D GCMs
The
project EUROCS aims to improve the treatment of cloud systems in global
and regional climate models. In addition, benefits will be also gained
for hydrology and severe weather issues. Clouds probably remain the largest
source of uncertainty affecting evaluations of climate change in response
to anthropogenic change. The recent interest to develop capability to predict
regional changes of climate, stress also the importance to better represent
clouds in models. EUROCS concentrates its efforts on 4 major and well identified
deficiencies of climate models:
The
strategy used in EUROCS to address these issues is based on the use of
a hierarchy of models and observations to integrate cloud studies across
the full range of scales. Numerical models range from General Circulation
Models (GCMs) through Single Column models (SCMs) to Cloud Resolving Models
(CRMs) and Large Eddy Simulations (LES). Observations which will be used
will vary from global satellite measurements to local observations of individual
clouds through lidar and millimetric radars.
To
produce comprehensive 4-D data sets using several LES models and CRMs on
cases defined above which address critical problems associated with the
prediction of cloud in regional and global climate and Numerical Weather
Prediction (NWP) models.
To
use the LES/CRM data sets to investigate deficiencies in climate and NWP
models using 9 different SCMs as a test bed. Specific issues to be addressed
will be the general failure of climate regional and global models to predict
stratocumulus amounts, the diurnal triggering of boundary layer convection
and deep precipitating convection over land, and the lack of sensitivity
of deep convection development on moisture profile in these models. Once
the reasons of deficiency are identified, physically-grounded corrections
will be brought in SCMs.
To
improve climate and NWP models ability to represent both the mean structure
(horizontally and vertically) as well as time variability of cloud water
and cover for the critical cases defined above. Six different European
climate models will be used in EUROCs making it of large benefit to the
whole community.
To
bring together a critical mass of the scientific community across Europe
working in various areas of Cloud and Climate research, with the focused
aim of improving cloud representations in climate and NWP models.
The
project mainly aims to improve the treatment of cloud systems in global
and regional climate models, which directly relates to the RTD priority
2.1.3 "improved model treatment of physical processes (in particular clouds)."
In addition, benefits will also be gained for hydrology and severe weather
issues (RTD 1.5.2 "Improved flood and drought forecasting")..
Clouds probably remain
the largest source of uncertainty affecting evaluations of climate change
in response to anthropogenic change. That explains for a large part why
the range of simulated temperature changes in response to a CO2 doubling
(1.5 to 4.5 C) is quite invariant for almost 20 years (e.g. Report of latest
Intergovernmental Panel on Climate Change: Dickinson et al. 1996). The
recent interest to develop capability to predict regional climate changes
stress the importance to better represent clouds in models. For example,
the prediction of distributions of mean and extreme precipitation is highly
dependent on the cloud representation in models. The climate community
must thus give more consideration to the problem of cloud representation
in General Circulation Models (GCMs) and Limited Area Models (LAMs) which
are applied to climate issues. As most of European models applied to climate
issues are also used to produce short and medium range forecasts, prediction
of severe weather systems will directly benefit from EUROCS.
The present investigators
have chosen to concentrate their efforts on 4 major and well identified
deficiencies of climate models:
·stratocumulus
over ocean,
·diurnal
cycle of cumulus,
·diurnal
cycle of precipitating deep convection over continents,
·sensitivity
of deep convection development on the moisture profile.
The
strategy to be used in EUROCS (Figure 2) is
based on the use of a hierarchy of models and observations to integrate
cloud studies across the full range of scales (Figure 1). Numerical models
range from General Circulation Models (GCMs)
through Single Column Models (SCMs) to Cloud Resolving Models (CRMs)
and Large Eddy Simulations (LES). All these models exist in Europe but
need to be applied along a coordinate way to efficiently solve the issues
addressed by EUROCS. Table 1 illustrates the summary of Partners and their
corresponding numbering together with the type of numerical models used
in Eurocs.
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CNRM-GAME
(CNRS & Meteo-France)
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ECMWF
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UKMO
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IMAU
(University of Utrecht)
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INM
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SMHI
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LMD
(CNRS)
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MPI
(MPG-IMET)
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KNMI
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UL (ICTE)
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The
last step of the strategy is to run 5 different GCMs including improvements
of cloud representations and to look at the general representation of clouds
and dynamic features, focusing on diurnal variations of shallow and deep
convection and stratocumulus cover as compared to available satellite observations
(ERBE, ISCCP, CLAUS) and results from runs with previous cloud representation.
A Limited Area Model (LAM) will also be used to look at the impact of improved
cloud parameterization in the prediction of regional climate.
The project has been
designed around 5 main workpackages WP1 to WP5.
WP1 and WP2 will be
concerned with the production of a 4D comprehensive data set using LES/CRMs
on the 4 chosen cases addressing the major issues identified above. The
results of LES/CRMs will be inter-compared and observed. Activities in
WP1 and WP2 will occur within the first 18 months.
WP3 and WP4 will use
the datasets issued from WP1 and WP2 together with SCM to identify the
reasons for deficiencies of cloud representation in GCMs. Once the reasons
for deficiencies have been identified, physically-grounded corrections
will be included in the SCMs. To achieve the goals of WP3 and WP4, the
partners involved will need new diagnoses from LES/CRMs simulations.
WP5 will use the first
improved cloud representation in 5 different GCMs and 1 LAM to provide
a framework where all the interactions are present. GCMs will carry out
model integrations at the seasonal time scale (3 months or more, for different
seasons). Preliminary tests of new cloud schemes will also be made on 10-day
periods. Some long climates at high horizontal resolution will also be
performed with the regional model forced by ECMWF analysis. A first comparison
of characteristics of stratocumulus, diurnal cycle of shallow and deep
convection as simulated by current and improved GCMs with available satellite
observations (ERBE, ISCCP, CLAUS) will be made.
The last six months
of the project will be partly devoted to finalizing the improvement of
cloud schemes. The comparison with satellite observations of 6 climate
models will give insights on the effect of the first set of improved cloud
schemes. Some deficiencies are to be expected between simulations and observations.
Inter-comparison of climate models on specific points will be useful from
this point of view. At this stage, it will then be important to make new
changes in cloud schemes using the CRM datasets and SCMs. Final climate
runs will be made with these last improvements as well as final comparisons
with satellite observations.
Participant
(P)
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Contractors
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Country
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P1
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Centre National
de la Recherche Météorologique/Groupe d’Etude de l’Atmosphere
Meteorologique
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France
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P2
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European
Centre for Medium-range Weather Forecasts
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United
Kingdom
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P3
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UK
Meteorological Office
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United
Kingdom
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P4
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Utrecht
University
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The
Netherlands
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P5
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Instituto
Nacional de Meteorologia
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Spain
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P6
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Swedish
Meteorological and Hydrological Institute
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Sweden
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P7
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Laboratoire
de Météorologie Dynamique
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France
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P8
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Max-Planck-Institut
fuer Meteorologie
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Germany
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P9
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Royal
Netherlands Meteorological Institute
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The
Netherlands
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P10
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University
of Lisbon
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Portugal
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Project
Coordinator:
P1Jean-Luc REDELSPERGER – CNRM-GAME
Laboratory
Coordinators:
P2Anton BELJAARS - ECMWF
P3Stephen DERBYSHIRE - UK Meteorological Office
P4Peter DUYNKERKE - Utrecht University
P5Joan CUXART RODAMILANS - Instituto Nacional de Meteorologia
P6Colin JONES - Rossby Center, SMHI
P7Jean-Yves GRANDPEIX - LMD
P8Andreas CHLOND - Max Planck – Institut Für Meteorologie
P9Pier SIEBESMA - KNMI
P10Pedro MIRANDA - ICTE – Centro de Geofisica, Universidade De Lisboa
I.Stratocumulus
over the ocean -Peter
Duynkerke & Stephan De Roode
II.Diurnal
cycle of cumulus-Geert
Lenderink & Pier Siebesma
III.Diurnal
cycle of precipitating deep convection over continents-Françoise
Guichard
IV.Sensitivity
of deep convection development on the moisture profile-Stephen
Derbyshire