Greg Holland

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Modeling Regional Climate Providing Western
States with Useable Climate Predictions
Greg Holland NCAR gholland_at_ucar.edu
Utahs Changing Climate Utah Energy Forum April
2009
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Simulation of 20th Century Warming
Meehl et al, 2004 J. Climate.
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Uncertainties in Regional Change
Sub-Saharan Rainfall
Model 1
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Why Nested Regional Climate Modeling?

• Climate models are the main tool for assessing
  future climate variability, and the only useful
  tool for assessing human-induced climate change
• Current climate models are far too coarse to
  resolve critical details of mountain
  precipitation
• Current computing facilities cannot support
  global climate model predictions at the required
  regional scales.

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Why is Model Resolution Important?
Current Weather Model Grid (1-2 km, would
completely cover the area)
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Why is Model Resolution Important?
The mountainous area of UTAH was virtually
transparent to the last IPCC simulations.
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Resolution and Climate Model Biases
Mean State Surface Temperature
Multi-Model Observations
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So What is the Big Deal?Cant We Just Run the
Models at the Required Resolution!

• Last IPCC Assessment Century Model Grid Spacing
  180 km Next IPCC Decadal Model Grid Spacing 55
  km.
• Increased Computing Power Required 100 fold
• Increased Computing Power Required to get to
  Current Weather Capacity 100,000 fold
• By Moores Law of doubling power every 2 years
  this will take gt40 years

3 Spatial Dimensions Plus Time
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Possible Approaches to Decadal Regional
Predictions

• Statistical downscaling
• Nested Regional Climate Modeling

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Current Work The North American Regional Climate
Change Assessment Program (NARCCAP)
Initiated in 2006, it is an international program
that will serve the climate scenario needs of the
United States, Canada, and northern Mexico.

• Exploration of multiple uncertainties in regional
  
• model and global climate model regional
  projections.
• Development of multiple high resolution regional
• climate 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

www.narccap.ucar.edu
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NARCCAP PLAN Phase II
A2 Emissions Scenario
GFDL
CCSM
HADCM3
CGCM3
CAM3 Time slice 50km
GFDL Time slice 50 km
1971-2000 current
2041-2070 future
Provide boundary conditions
CRCM Quebec, Ouranos
RegCM3 UC Santa Cruz ICTP
HADRM3 Hadley Centre
MM5 Iowa State/ PNNL
RSM Scripps
WRF NCAR/ PNNL
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Precipitation Prediction Example
Winter Precipitation difference -- future vs.
current
NCAR CCSM3
NCARCAM3
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Next Stage the Nested Regional Climate Model
Approach
Bringing the NCAR world-leading climate and
weather models and expertise together to tackle
regional climate prediction on decadal time scales
Phase 1 Tropical simulations for current
climate Results to be published in Special Issue
of Climate Dynamics
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The Community Climate System Model (CCSM)

• A comprehensive climate model to
• Investigate and predict seasonal and interannual
  variability in the climate
• Explore the history of Earths climate.
• Estimate the future of the environment for policy
  formulation.
• Developed by NCAR, National Laboratories and
  Universities
• Used for the largest ensemble of simulations for
  the IPCC AR4

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The Weather Research Forecasting Model (WRF)

• The most used weather model on earth, with gt9,000
  users in 115 countries and gt20 24/7 operational
  centers (including NOAA and USAF)s
• Suitable for a broad spectrum of applications
  across scales ranging from meters to thousands of
  kilometers

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NRCM Phase II North Atlantic and North American
Regional Climate Changes

• The goal is to simulate the effects of climate
  change on precipitation across the intermountain
  West States and tropical cyclones, with a focus
  on the Gulf of Mexico.

• 36, 12 and 4 km WRF domains nested into CCSM
• 1996-2005, then time slices of 2020-2030 and
  2045-2055
• Multi-member ensembles for each period

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12 km Simulation of September 2046
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4 km Simulation September 2005
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NRCM Phase II Analysis

• Foci
• Hurricanes in the Gulf of Mexico for the Offshore
  Oil Industry and coastal communities (funded)
• Wind Energy Climatology for DOE and the Wind
  Energy Community (DOE proposal)
• Intermountain West Precipitation for Western
  States planning (WGA discussions).

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Current Development Global Weather-Climate
Modeling
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Summary Regional Climate Prediction on Decadal
Time Scales

• Requires Nested Regional Climate Models
• Current work at relatively course resolution
  under NARCCAP is providing immediate indications.
• Next stage is the Nested Regional Climate Model
• Coupling weather and climate models to
• utilize the best of both
• improve fidelity of global climate simulations
• provide forecasts of changes in high impact
  weather/climate
• Inform development of next-generation models
• Research stage is leading towards seamless
  weather-climate prediction