Transcript RACM (part 1) - International Arctic Research Center

Regional Arctic Climate System Model
(RACM) – Project Overview
A 4-year (2007-2011) DOE / SciDAC-CCPP project
Participants:
Wieslaw Maslowski
John Cassano
William Gutowski
Dennis Lettenmeier
(PI)
(co-PI)
(co-PI)
(co-PI)
Greg Newby, Andrew Roberts,
Juanxiang He, Anton Kulchitsky
- Naval Postgraduate School
- University of Colorado
- Iowa State University
- University of Washington
- Arctic Region Supercomputing Center /
International Arctic Research Center
Dave Bromwich (OSU), Gabriele Jost (HPCMO), Tony Craig (NCAR),
Jaromir Jakacki, Robert Osinski (IOPAN), Mark Seefeldt (CU), Chenmei Zhu (UW),
Justin Glisan, Brandon Fisel (ISU), Jaclyn Kinney (NPS)
Arctic System Modeling Workshop, Montreal, Canada, July 16-17, 2009
Need for Regional
Arctic Climate System Model
• There are large errors in global climate system
model simulations of the Arctic climate system
• Observed rapid changes in Arctic climate system
– Sea ice decline
– Greenland ice sheet
– Temperature
• Arctic change has global consequences
– Sea ice change can alter the global energy balance
and thermohaline circulation
Observed Rate of Loss Faster Than GCM Predicted
"A linear increase in heat in the Arctic Ocean will
result in a non-linear, and accelerating, loss of sea
ice.“ Norbert Untersteiner, Prof. Emeritus, Univ. of Washington, July 2006
Adapted from Stroeve et al., 2007
NSIDC ice extent
GCM Comparison:
September 2002
3
3
Regions:
1 – Greenland Shelf
2 – Eastern Arctic
3 – Western Arctic
2
2
1
1
- Too much ice in the western Arctic
and over Siberian shelves through 2007
- Too little ice in the eastern Arctic through 2007
3
3
2
1
2
1
Selected IPPC-AR4 model September sea ice results
CCSM3
HadGEM1
GFDL-CM2
MIROC
Ocean: Heat Transport
25 yr mean volume transport (Sv) / Heat Transport
Observations
NAME: POP/CICE CCSM
Fram Strait
(Inflow)
7.0 Sv / 50 TW
6.9 Sv / 45 TW
2.0 Sv / 17 TW
FJL – NZ
(Net)
NA / Near zero
2.6 Sv / 2.2 TW
4.35 Sv / 31 TW
‘NPS’ TRANSPORTS (Maslowski et al., JGR, 2004)
Fram Strait ‘in’ obs estimates - Courtesy of A. Beszczynska-Möller, AWI
FJL-NZ - (Gammelsrod et al., JMS 2008)
Our rationale for developing a regional
Arctic climate System Model (ASM)
1. Facilitate focused regional studies of the Arctic
2. Resolve critical details of land elevation, coastline
and ocean bottom bathymetry
3. Improve representation of local physical processes
& feedbacks (e.g. forcing & deformation of sea ice)
4. Minimize uncertainties and improve predictions of
climate change in the pan-Arctic region
RACM Science Objective
To synthesize understanding of past and present states
and thus improve decadal to centennial prediction of
future Arctic climate and its influence on global climate.
Specific Goals
• develop a state-of-the-art Regional Arctic Climate system
Model (RACM) including high-resolution atmosphere,
ocean, sea ice, and land hydrology components
• perform multi-decadal numerical experiments using high
performance computers to understand feedbacks,
minimize uncertainties, and fundamentally improve
predictions of climate change in the pan-Arctic region
• provide guidance to field observations and to GCMs on
required improvements of future climate change
simulations in the Arctic
RACM Domains for Coupling and Topography
-Innermost POP / CICE
gridcell ≤10km
- Middle – WRF / VIC
gridcell ≤50km
- Outermost – POP/WRF
Pan-Arctic region to
include:
- all sea ice covered
ocean in the northern
hemisphere
- Arctic river drainage
- critical inter-ocean
exchange and transport
- large-scale
atmospheric weather
patterns (AO, NAO,
PDO)
Flux Coupler
-
CCSM/CPL7
Coupling of WRF and CPL7
• Led by Juanxiong He with contributions from
Greg Newby, Tony Craig, and Mark Seefeldt
• Minimize changes to WRF and CPL7
• Add new surface routine to WRF to accept
fluxes from CPL7
• WRF/CPL7 working in global configuration
• Currently implementing regional domain with
WRF/CPL7
Coupling of VIC and CPL7
• Led by Dennis Lettenmaier and Chunmei Zhu
with Tony Craig
• Currently have VIC coupled to CPL7 running in
“data” mode
• Next step is to
resolve issues
with interactive
VIC / atmosphere
simulations
Coupling of POP / CICE with CPL7
• Led by Wieslaw Maslowski, Jaromir Jakacki,
Tony Craig and Gabriele Jost
• POP/CICE/CPL7 runs in a spinup mode with
WRF in “data” and VIC in “slab” mode
• Minimal computational cost using CPL7
Modeled Sea Ice Thickness Loss
NPS Arctic Model Effort (NAME):
Sea ice thickness (m) in (a) 1982, (b) 1992, (c) 2002
(Maslowski et al., 2007)
Modeled Ice Extent, Thickness, and Volume
Between 1997-2004:
- annual mean sea ice
concentration has
decreased by ~17%
- mean ice thickness has
decreased by ~0.9 m
or ~36%
- ice volume decreased by
40%, which is >2x the
rate of ice area decrease
Ocean: Heat Transport
• Modeling challenge: Inflow of Pacific/Atlantic water
and impacts on sea ice
– Pacific water enters via
narrow Bering Strait
– Outflow via Fram Strait
vs inflow from
Atlantic bottom water
– Heat loss from Pacific
and Atlantic water prior
to entering Arctic
Mean Oceanic Heat
Convergence (0-120 m)
Sea Ice Shear
in CICE-9km
Ice thickness
distribution and
deformations
are critical to airsea interactions
and challenging to
represent in GCMs
RACM 2009-2010 Outlook
• Finalize component model / CPL7 coupling
• Fully coupled simulations
• Evaluation of fully coupled model
• Multi-decadal simulations
– Retrospective
– Future climate
• Long-term goals
– Regional simulations for IPCC reports
– Additional climate system components
• Ice sheets
• Biogeochemistry