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Regional climate modeling over South America: challenges and
perspectives
Silvina A. SolmanCIMA (CONICET-UBA)
DCAO (FCEN-UBA)
UMI- IFAECI 2nd Meeting, Buenos Aires. ArgentinaApril 25-27- 2011
Outline
– Why do we need Regional Climate models?– How well do models represent regional climate
over South America?• Main shortcomings and strengths of RCMs over South
America: the CLARIS-LPB contribution.
– Sources of uncertainty in regional climate simulations
– Possible research topics
La información climática a escala regional es crítica para los estudios de impactoWhy do we need Regional Climate models?
AOGCM
Regional Climate Model (RCM)
How well do models represent regional climate over South America?
CLARIS-LPBThe EU FP7 CLARIS LPB projectMain goal: To predict the regional climate change impacts on La Plata Basin (LPB) in South America, and at designing adaptation strategies
To provide an ensemble of regional hydroclimate scenarios and their uncertainties for climate impact studies.
CORDEXInitiative promoted by the TFRCD /WCRP Main goal: To Provide a quality-controlled data set of RCD-based information for the recent historical past and 21st century projections, covering the majority of populated land regions on the globe.
To Evaluate the ensemble of RCD simulations.
to provide a more solid scientific basis for impact assessments and other uses of downscaled climate information
CORDEX: South America/CLARIS-LPB
Model Evaluation Framework
Climate ProjectionFramework
ERA-Interim LBC 1989-2008
Multiple AOGCMsHadCM3-Q0, ECHAM5OM-R3, IPSL
A1BContinuous runs &
Timeslices (2010-2040 and 2070-2100)
Regional AnalysisRegional Databanks
CLARIS-LPB coordinated experiments over South America:
ERA-Interim boundary forcingRCM/Institution Country Contact person
RCA/SHMI Sweden Patrick Samuelsson
MM5/CIMA Argentina Silvina Solman, Natalia Pessacg
RegCM3/USP Brazil Rosmeri Porfirio da Rocha
REMO/MPI Germany Armelle Reca Remedio, Daniela Jacob
PROMES/UCLM Spain Enrique Sánchez , R. Ochoa
LMDZ/IPSL France Laurent Li
ETA/INPE Brazil Sin Chou, José Marengo
WRF/CIMA Argentina Mario Nuñez
• Up to date most RCMs evaluations have been focused on the mean climate, but what about higher order climate variability?
Diurnal cylce Mesoscale variabilityIntraseasonal variability
Interannual to interdecadal variability
Examples of precipitation variability over different time-scales
What do we know?•Overall model performance of the mean climate• Systematic biases of the simulated mean climate
• Largest biases mainly over tropical South America• Warm and dry biases over tropical regions: Land surface?• Dry and bias over LPB: resolution?
• Uncertainty on simulating mean climate (inter-model spread)– Largest biases mainly over tropical regions
But we don’t know much about …• Model performance on higher order variability patterns• Systematic biases on higher order variability patterns• Uncertainty in simulating higher order variability patterns
Internal variability of a RCM over South America
• MM5 model• OND 1986• 4 members(Solman and Pessacg, 2010)
•How large is the internal variability for long-term climate simulations?
•Annual cycle of the internal variability?
CLARIS-LPB CORDEX
Model Evaluation Framework
Climate ProjectionFramework
ERA-Interim LBC 1989-2008
A1BContinuous runs &
Timeslices2010-2040; 2070-2100
Regional AnalysisRegional Databanks
RCP4.5, RCP8.51951-2100 or timeslices
Need for a collaborative framework to provide CORDEX projections over South America
RCM perspectives
• Need for evaluating RCMs in terms of variability patterns.
• Understanding the causes for the systematic biases of the simulated mean climate
• Need for evaluating the internal variability of RCMs to put the climate response patterns in the context of the noise level.
• Need for a collaborative framework to provide CORDEX projections over South America
Conclusions• South American climate is characterized by variability patterns on
a broad range of timescales and different spatial distributions.• Regional climate models are able to simulate the mean climatic
conditions, though large uncertainties and systematic biases can be identified over some regions /variables.
• Studies using Regional Climate models focused on the response of the regional climate to external forcings (increasing CO2; land use changes or soil moisture conditions) show that the climate response is very heterogeneous both spatially and temporally.
• Some particular regions of South America exhibit large responses, mainly in terms of changes in precipitation, temperature and moisture flux to these external forcings.