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Running the Community Climate Simulation Model (CCSM) at NERSC. CAM T340- Jim Hack. Adrianne Middleton National Center for Atmospheric Research Boulder, Colorado. 1870 Control Run. TS (Globally averaged surface temperature). Years (constant-1870-conditions control run). 0. 500-1000.
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Running the Community Climate Simulation Model (CCSM) at NERSC CAM T340- Jim Hack Adrianne Middleton National Center for Atmospheric ResearchBoulder, Colorado
1870 Control Run TS (Globally averaged surface temperature) Years (constant-1870-conditions control run) 0 500-1000
5 Member 1870-2000 Historical Ensemble A C B D E 2000 2000 2000 2000 2000 TS (Globally averaged surface temperature) 1870 1870 1870 1870 1870 Years 360 a 380 b 400 c 420 d 440 e 500 0
Model Vs Observations Climate of the last Millennium Caspar Ammann NCAR/CGD
CCSM 3.0 T85 on bassi Coupler 8 pes Land 16 pes Atmosphere 128 pes Ocean 40 pes Sea Ice 16 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
Data Assimilation HPC dimensions of Climate Prediction New Science Better Science (new processes/interactions not previously included) (parameterization → explicit model) • Spatial • Resolution Timescale (Length of simulations) (simulate finer details, regions & transients) Ensemble size (decadal prediction/ initial value forecasts) (quantify statistical properties of simulation) Lawrence Buja (NCAR) / Tim Palmer (ECMWF)
70 10 10 10 10 10 10 10 10 HPC dimensions of Climate Prediction New Science Better Science ESM+multiscale GCRM Code Rewrite Earth System Model • Spatial • Resolution • (x*y*z) Climate Model Timescale (Years*timestep) Regular10000 ? 400 0.2° 22km 1.4° 160km 1Km 100yr* 20min 1000yr* 3min 1000yr * ? AMR 1000 5 Today Terascale Cost Multiplier 2010 Petascale 50 500 Data Assimilation Ensemble size 2015 Exascale Lawrence Buja (NCAR)
Paleoclimate IPCC AR3 1998 GlobalGeneral Circulation Continentallarge-scaleflow BGC/Carbon CycleSpin-ups IPCC AR4 2004 4TF Regional MJO convergence IPCC AR5 2010 500TF local Resolve Hurricanes CCSM Grand Challenge 2010 1PF
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 Community Climate System Model (CCSM)
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