Validation of GCM, and the need of High resolution atmospheric and hydrological model

Vicente Barros and Mariano ReVicente Barros and Mariano Re

San José de Costa RicaSan José de Costa Rica

28 May 200328 May 2003

Forcings of the Plata River level

Tributarios

Onda de marea

Vientos

Tributaries:

-The Plata basin covers 3.2 M. Km²

- Runoff depends on Precipitation and evaporation (Temperature)

- How good are precipitation and temperature scenarios?

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-10PP CSIRO-UDEL -APRIL (1961-1999) (m m /dy)

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PP CSIRO-UDEL -JULY (1961-1999) (m m /dy)

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PP CSIRO-UDEL -OCTOBER (1961-1999) (m m /dy)

PrecipitationClimate minus

simulatedprecipitation

scenarios

Validation of climate models:precipitation

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-10PP HADCM3-UDEL - ANNUAL (1961-1999) (m m /dy)

Difference in Difference in annualannual

precipitation precipitation between between HADCM3 HADCM3

experiment experiment and and

observedobserveddatadata

(mm/day(mm/day)~ 30% less than

observed

Precipitation features (PFs) for 5 x 5 degree boxes Seasonal distribution of during Dec.1997 to Nov.2000 observed by the TRMM Precipitation Radar (E. Zipser, G. Mota, and S. Nesbitt, 2002) For more details about PF definition see Nesbitt et al., 2000, J. Climate, 13, 4087-4106.

850850 hPa Circulation Composites - JanuaryhPa Circulation Composites - January

Warm EventsWarm Events Cold Cold EventsEvents

Precipitation is too understimated by GCM: Some physical processes are misrepresented

Difficulties with downscaling andPerturbation techniques

Hope: CRM models

GCM runned with low resolution Do not resolve Meso Convective Systems Do not represent topography

correctly Parameterization of convective activity?

Remote ocean forcing? Frequency and intensity of synoptic perturbations?

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SST at Niño 3.4 from HadCm3 SRES A2 experiment

SST at Niño 3.4 from GFDL SRES A2 experiment

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ETA MODEL EXPERIMENT: Domain and features

Workstation ETAAdapted by M. Pyle (NOAA)

Horizontal resolution: Grid of 1°lat.X 1°long

Vertical: 60 levels Time step: 360 s

Running in aSystem CRAY, Origin 2000.

40 processors

Experiment: 10 years with NCEP/NCAR Reanalysis

Mean sea level:

IPCC Scenarios

Figure 11.12: Global average sea level rise 1990 to 2100 for the SRES scenarios.

Figure 11.13: Sea level change in metres over the 21st century resulting from thermal expansion and ocean

circulation changes calculated from AOGCM experiments following the IS92a scenario

Wind effect on water level is not linear

Thus:The mean water level has to be calculated by running the hydrodinamic model forced by instantaneous winds