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Adrianne MiddletonNational Center for Atmospheric ResearchBoulder, Colorado
CAM T340- Jim Hack
Running the Community Climate Simulation Model (CCSM) at NERSC
0 500-1000Years (constant-1870-conditions control run)
TS
(G
loba
lly a
vera
ged
sur
face
te
mpe
ratu
re)1870 Control Run
380b
400c
420d
440e
360a0
500Years
TS
(G
loba
lly a
vera
ged
sur
face
te
mpe
ratu
re)
1870
2000
A B C D E
18701870
1870
1870
20002000
2000 2000
5 Member 1870-2000 Historical Ensemble
CCSM IPCC Graph
Climate of the last Millennium
Caspar AmmannNCAR/CGDModel Vs Observations
CCSM 3.0 T85 on bassi
Atmosphere128 pes
Ocean40 pes
Coupler8 pes
Sea Ice16 pes
Land16 pes
•Small number of processors (208), but long run time (16 days)•Want 5 model years/day•Queue is generally 3 days long•Model runs roughly 1 model year/3 hours or max 4 years/run slot
HPC dimensions of Climate Prediction
Data Assimilation
New Science
Spatial Resolution
Ensemble size
Timescale
Better Science(parameterization → explicit model)
(new processes/interactions not previously included)
(simulate finer details, regions & transients)
(quantify statistical properties of simulation) (decadal prediction/ initial value forecasts)
(Length of simulations)
Lawrence Buja (NCAR) / Tim Palmer (ECMWF)
Spatial Resolution (x*y*z)
Ensemble size
Timescale (Years*timestep)
TodayTerascale
5
50
500
Climate Model
70
10 2010Petascale
1.4°160km
0.2°22km
AMR
1000
400
1Km
Regular 10000
Earth System Model
100yr*20min
1000yr*
3min1000yr * ?
Code Rewrite
Cost Multiplier
Data Assimilation
ESM+multiscale GCRMNew Science Better Science
HPC dimensions of Climate Prediction
?
Lawrence Buja (NCAR)
10
1010
10
10 10
10
2015
Exascale
T42 2.8°
FV 2.0°
T85 1.4°
FV 1.0°
T170 0.7°
FV 0.5°T340 .36° FV 0.25°
0
50
100
150
200
250
300
Horizontal Grid Size (Km)
310km
220km
160km
110km
78km
55km
39km
28km
GlobalGeneral
Circulation
Continentallarge-scale
flow
Regional
local
Paleoclimate
BGC/Carbon CycleSpin-ups
MJO convergence
Resolve Hurricanes
IPCC AR42004 4TF
IPCC AR31998
IPCC AR52010 500TF
CCSM GrandChallenge2010 1PF
Community Climate System Model (CCSM)
Current Configuration• Hub and spoke design with 5 executables• Exchange boundary information through coupler• Each code quite large: 60-200k lines per code• Need 5 simulated years/day --> Must run at “low” resolution• Standard configuration run at scaling sweetspot of O(200) processors
Petascale Configuration• Single executable• 5 years wall-clock day• Targeting 10K - 120K processors per simulation
– CAM @ 0.25° (30 km, L66)– POP @ 0.1° Demonstrated 8.5 years/day on 28K Bluegene– Sea-Ice @ 0.1° Demonstrated 42 years/day on 32K Bluegene– Land @ 0.1°– Cpl
Data Processing
• Ample disk space (We use up to 600 GB at a time)• Ample memory (We use 2-4 GB)• Long serial interactive jobs are fine• Software we use includes the netCDF Operators (NCO),
NCAR Graphics Command Language (NCL), Ferret 5.81, and more.
“It's dependable, reliable, robust, and fits my requirements quite well.” -- Gary Strand
Thanks! Any Questions?