Hélène Côté and Daniel Caya

Climate Simulations Group

Consortium Ouranos

Variability and Extremes in the CRCM

Development of Scenarios of Climate Variability and Extremes: Current Status and Next StepsVictoria, 16-17 October 2003

Outline• Current status of CRCM

– Policy Run II vs Policy Run III– Production runs with version 3.6.1– Preliminary results (the first 5 years of the 25-year run)– Next operational version: CRCM 3.6.3– Development of CRCM 4.0

• Variability issues in regional climate modelling• Modelling the extremes

– The data we have– What we plan to do

• Validation issues• How to improve the model

From Policy Run II to Policy Run III 3.5.1 vs 3.6.1

Radiation Fouquart and Morcrette unchanged

Land surface Beautified Bucket ( 1 layer + force-restore)

unchanged

Convection Kain-Fritsch (1990) Bechtold-Kain-Fritsch (Bechtold et al 2001)

Clouds F (relative humidity) F (relative humidity) + convective clouds

Boundary layer Bulk transfert, mixing lengh-K unchanged

Atmospheric composition

Specified [O3] [CO2] unchanged

Nesting Davies relaxation Spectral nudging

( Biner et al 2000 , Denis et al)

SSTs From Monthly GCM values From Daily GCM values or AMIP obs.

Lake Model No Mixed-layer (Goyette et al 2000)

Leap-year No Yes

New features Implicit treatment of Tg

Atmospheric budget

Current Simulations Configuration

• 45 km grid point spacing• 193 x 145 grid points• 29 vertical levels• Lid: 30 km • Archival : every 6 hours (pcp every timestep)

• Transient CO2

• Spinup period: 2 years

• Approx. 1 month CPU time per simulated year ….

• 5.7Gb of model outputs per simulated month….

Topography(m)

Policy Run IIdomain

Current SimulationsDriving data

Ocean Period Spectral nudging

CRCM Done(14/10/03)

NRA-1 AMIP 1973-1999

yes 3.6.1 133 / 364

NRA-1 AMIP 1973-1999

no 3.6.1 95 / 364

CGCM2  is92a 

CGCM2 1968-1994

yes 3.6.1 92 / 364

CGCM2 is92a

CGCM2 2037-2063

yes 3.6.1 90 / 364

CO2 Equivalent Concentration

IS92a CRCM

– CRCM CGCM2, 1968 -1994, 2037-2063

Precipitation rate (mm/day)5-year mean: Summer

CRCM/NCEP

CRU2

CRCM-CRU2

CRU2: Climatic Research Unit TS 2.020.5°X 0.5° (Mitchell et al. 2003)

Precipitation rate (mm/day)5-year mean: Winter

CRCM/NCEP

CRU2

CRCM-CRU2

Maximum Screen Temperature (ºC) 5-year mean: Summer

CRCM/NCEP

CRU2

CRCM-CRU2

Minimum Screen Temperature (ºC) 5-year mean: Summer

CRCM/NCEP

CRU2

CRCM-CRU2

CRCM Version 3.6.3

• Improve some biases of 3.6.1 related to the boundary layer: Retun the control from the planetary waves Too warm (Tmin) and too wet (pcp)

1-layer bucket too deep and very wet

Excessive cloud cover(Tmin too high)Too much evaporation

Too much preciptation

Planned SimulationsDriving data

Ocean Period Spectral nudging

CRCM Start

CGCM2 scenario *

CGCM2 scenario *

1xCO2

2xCO2

yes 3.6.3 Early 2004

CGCM2 scenario *

CGCM2 scenario *

1xCO2

2xCO2

yes 3.6.3 Early 2004

GCMx GCMx 1xCO2 2xCO2

yes 3.6.3 Early 2004

*We have to choose from CGCM2 simulations based on different CO2 emission scenarios.

GCMx: A different GCM

CRCM 4.0

• Prototype in development in collaboration with the CRCM Network (R.Laprise et al)– MC2 dynamics + GCMIII physics

• Ed Chan MSC, Virginie Lorant CCCma

– All CRCM physics and features need to be implemented

– Prototype to be completed in early 2005

Variability

• Longer timeserie to assess variablity– 25 years simulations instead of 10 years

• 2 compoments of the variability:– Intramonthly (seasonal) vs Interannual variability

– Intramonthly variability: difficult to validate due to a lack of temporal resolution of gridded observed datasets

• Results : Validation of interannual variability

Precipitation Rate (mm/day)5-year Interannual Standard-Deviation

WinterCRCM/NCEP

CRU2

CRCM-CRU2

Maximum Screen Temperature 5-year Interannual Standard-Deviation

WinterCRCM/NCEP

CRU2

CRCM-CRU2

Minimum Screen Temperature 5-year Interannual Standard-Deviation

WinterCRCM/NCEP

CRU2

CRCM-CRU2

CRCM monthly extremes

• Precipitations extremes : computed from precipitation archived every timestep (15 min)– Highest precipitation rate for different durations– Wet days for different thresholds– Dry days for different thresholds– Precipitation histogram

• Daily extremes of specific humidity (screen)• Daily screen temperature extremes• Highest gusts at the lowest level of the model

CRCM climate extremes(all in early stage of development)

• Records of the simulation

• Normals of the simulation

• Climate indices (Stardex, etc…)

• Precipitation histograms

• Temperature distributions

5-year January Daily Precipitation Histogram nearest gridpoint vs station data: Victoria

• From the 0.2 mm threashold– 124 / 155 rain days in CRCM

• 3 events above 25 mm during the simulation

• On average, – MSC obs: 17.8 / 31 (57%) rain days– CRCM : 24.8 / 31 (80%) rain days

• Precipitation too frequent

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5-year January Daily Precipitation Histogram nearest gridpoint vs station data: Kuujuaq

• From the 0.2 mm threashold– 100 / 155 rain days in CRCM

• 0 event above 25 mm during the simulation

• On average, – MSC obs: 15.4 / 31 (49.6%) rain

days– CRCM : 20.0 / 31 (64.5%) rain

days• Precipitation too frequent [0.2-5[

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Validation issues• Gridded climatologies

– Lack of resolution– Lack of temporal resolution – Lack of variables– Lack of information about the topography (except

CRU)

• CRCM – Limited time-series– Grid point vs station data– Interpolation of datasets on the CRCM grid

Improving regional climate models

• Better representation of surface caracteristics– variables used by land surface scheme

• Include smaller lakes – bathymetry, lake surface temperature, ice

– from 1968-1999

• Better parameterisations• CRCM ensembles