The North American Regional Climate Change Assessment Program

(NARCCAP)

Linda O. MearnsNational Center for Atmospheric Research

SAMSI Climate Change Workshop Research Triangle Park, NC

February 18, 2010

Global Climate Models

Regional Climate Models

What high resolution is really good for

• In certain specific contexts, provides insights on realistic climate response to high resolution forcing (e.g. mountains, complex coast lines)

• For coupling climate models to other models that require high resolution (e.g. air quality models – for air pollution studies)

Advantages of higher resolution

North America at 50 km grid spacing

North America at typical global climate model resolution

Hadley Centre AOGCM (HadCM3), 2.5˚ (lat) x 3.75˚ (lon), ~ 280 km

Putting Spatial Resolution in the Context of Other Uncertainties

• Must consider the other major uncertainties regarding future climate in addition to the issue of spatial scale – what is the relative importance of uncertainty due to spatial scale?

• These include: – Specifying alternative future emissions of

ghgs and aerosols – Modeling the global climate response to

the forcings (i.e., differences among AOGCMs)

Regional Modeling Strategy

Nested regional modeling technique • Global model provides:

– initial conditions – soil moisture, sea surface temperatures, sea ice

– lateral meteorological conditions (temperature, pressure, humidity) every 6-8 hours.

– Large scale response to forcing (100s kms)

• Regional model provides finer scale (10s km)

response

The North American Regional Climate Change Assessment Program (NARCCAP)

•Exploration of multiple uncertainties in regional model and global climate model regional projections

•Development of multiple high resolution regionalclimate scenarios for use in impacts assessments.

•Further evaluation of regional model performance over North America

•Exploration of some remaining uncertainties in regional climate modeling(e.g., importance of compatibility of physics in nesting and nested models)

•Program has been funded by NOAA-OGP, NSF, DOE, USEPA-ORD – 4-year program

Initiated in 2006, it is an international program that will servethe climate scenario needs of the United States, Canada, and northern Mexico.

www.narccap.ucar.edu

NARCCAP - TeamLinda O. Mearns, NCAR

Ray Arritt, Iowa State; Dave Bader, LLNL and Oakridge National Lab; Melissa Bukovsky, NCAR;

Richard Jones, Wilfran Moufouma-Okia, UK Hadley Centre; Sébastien Biner, Daniel Caya, Ouranos

(Quebec); Phil Duffy, Climate Central; Dave Flory, Iowa State; William Gutowski, Iowa State; Isaac Held,

GFDL; Bill Kuo, NCAR; René Laprise, UQAM; Ruby Leung, Yun Qian, PNNL; Larry McDaniel, Seth

McGinnis, Don Middleton, NCAR; Ana Nunes, Scripps; Doug Nychka, NCAR, John Roads*, Scripps; Steve

Sain, NCAR; Lisa Sloan, Mark Snyder, UC Santa Cruz, Gene Takle, Iowa State

* Deceased June 2008

NARCCAP Domain

Organization of Program• Phase I: 25-year RCM simulations using NCEP-Reanalysis

boundary conditions (1979—2004)

• Phase II: Climate Change Simulations

– Phase IIa: RCM runs (50 km res.) nested in AOGCMs current and future

– Phase IIb: Time-slice experiments at 50 km res. (GFDL and NCAR CAM3). For comparison with RCM runs.

• Quantification of uncertainty at regional scales – probabilistic approaches

• Scenario formation and provision to impacts community led by NCAR.

• Opportunity for double nesting (over specific regions) to include participation of other RCM groups (e.g., for NOAA OGP RISAs, CEC, New York Climate and Health Project, U. Nebraska).

Phase I

• All 6 RCMs have completed the reanalysis-driven runs (RegCM3, WRF, CRCM, ECPC RSM, MM5, HadRM3)

• Results are shown here for 1980-2004 from six RCMs

• Configuration:– common North America domain (some differences due

to horizontal coordinates)– horizontal grid spacing 50 km– boundary data from NCEP/DOE Reanalysis 2– boundaries, SST and sea ice updated every 6 hours

Regions Analyzed

Boreal forest

Pacific coast

California coast

Deep South

Great LakesMaritimes

Upper Mississippi

River

Coastal CaliforniaCoastal California• Mediterranean climate: wet winters and

very dry summers (Koeppen types Csa, Csb).

– More Mediterranean than the Mediterranean Sea region.

• ENSO can have strong effects on interannual variability of precipitation.

R. Arritt

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1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

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/day

RCM3 MM5IECPC CRCMWRFP HRM3Observed (GPCC) Observed (UDEL)Observed (CRUT) Ensemble

1982-83 El Nino

1997-98 El Nino

multi-year drought

Monthly time series of precipitation in coastal California

small spread, high skill

Correlation with Observed Precipitation - Coastal California

Model Correlation

HadRM3 0.857

RegCM3 0.916

MM5 0.925

RSM 0.945

CRCM 0.946

WRF 0.918

Ensemble 0.947

Ensemble mean has a higher correlation than any model

All models have high correlations with observed monthly time series of precipitation.

Deep SouthDeep South• Humid mid-latitude climate with substantial

precipitation year around (Koeppen type Cfa).

• Past studies have found problems

with RCM simulations of

cool-season precipitation in this region.

Monthly Time Series - Deep South

Model Correlation

HadRM3 0.489

RegCM3 0.231

MM5 0.343

RSM 0.649

CRCM 0.649

WRF 0.513

Ensemble 0.640

Two models (RSM and CRCM) perform much better. These models inform the domain interior about the large scale.

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1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

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RCM3 MM5I ECPCCRCM WRFP HRM3Observed (GPCC) Observed (UDEL) Observed (CRUT)Ensemble

Ensemble (black curve)

Monthly Time Series - Deep South

Model Correlation

HadRM3 0.489

RegCM3 0.231

MM5 0.343

RSM 0.649

CRCM 0.649

WRF 0.513

Ensemble 0.640

RSM+CRCM 0.727

A “mini ensemble” of RSM and CRCM performs best in this region.

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1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

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RCM3 MM5I ECPCCRCM WRFP HRM3Observed (GPCC) Observed (UDEL) Observed (CRUT)Ensemble

Ensemble (black curve)

A2 Emissions Scenario

GFDL CCSMHADCM3CGCM3

1971-2000 current 2041-2070 futureProvide boundary conditions

MM5Iowa State/PNNL

RegCM3UC Santa CruzICTP

CRCMQuebec,Ouranos

HADRM3Hadley Centre

RSMScripps

WRFNCAR/PNNL

NARCCAP PLAN – Phase II

CAM3Time slice

50km

GFDLTime slice

50 km

GCM-RCM Matrix

GFDL CGCM3 HADCM3 CCSM

MM5 X X1

RegCM X1** X**

CRCM X1** X

HADRM X X1**

RSM X1 X

WRF X X1

*CAM3 X

*GFDL X**

1 = chosen first GCM *= time slice experiments Red = run completed ** = data loaded

AOGCMS

RCMs

Phase II (Climate Change) Results

Change in Winter TemperatureUK Models

Change in Summer TemperatureUK Models

Uncertainty across two RCMs nested in same GCM for % Change in Winter Precipitation

Global Model Regional Model 1 Regional Model 2

Effect of two different GCMs driving one RCM – % change in winter precipitation

GCMs

RCM RegCM3

GFDLCGCM3

A2 Emissions Scenario

GFDLAOGCM

NCARCCSM

Global Time Slice / RCM Comparisonat same resolution (50km)

Six RCMS50 km

GFDLAGCM

Time slice50 km

CAM3Time slice

50km

compare compare

RegCM3 in GFDL% Change Precip - Winter

Quantification of Uncertainty

• The four GCM simulations already ‘situated’ probabilistically based on earlier work (Tebaldi et al., 2004, 2005)

• RCM results nested in particular GCM would be represented by a probabilistic model (derived assuming probabilistic context of GCM simulation)

• Use of performance metrics to differentially weight the various model results – will use different metrics – including process level expert judgment - determine sensitivity of final pdfs to various methods

NARCCAP Project Timeline

1/06 8/09

6/1012/07

AOGCM Boundaries available

9/07

Phase 1

Future Climate 1

9/08

Current Climate1

Current and Future 2 Project Start

Time slices

Archiving Procedures - Implementation

Phase IIb

Phase IIa

The NARCCAP User Community

Three user groups:

• Further dynamical or statistical downscaling

• Regional analysis of NARCCAP results

• Use results as scenarios for impacts and adaptation

studies

www.narccap.ucar.edu

To sign up as user, go to web site – contact Seth McGinnis

,

mcginnis@ucar.edu

Over 200 hundred users registered

End