1. Community Earth System Model (CESM) for CMIP6
Office of Science

2. Target CESM2 and CMIP6 versions: ocean at 1o
AOGCM physical climate (1o, low-top)
+ biogeochemistry (1o, CO2 emission and/or concentration driven, low-top)
+ atmospheric chemistry + biogeochemistry (1o, CO2 emission driven, high-top; WACCM)
AOGCM physical climate (1/4o atm, low-top)
(a few simulations with AOGCM 1/4o atm, 1/10o ocean)
Low-top: 32 levels up to 40 km
High-top: 70 levels up to 150 km

3. 2015-2016 Timeline for CESM2 development
now
Spring 2015
June 2015
Oct
Spring 2016
June 2016
Decision on CAM5.5
CAM5.5 to developers
Coupled simulations
Coupled simulations
CESM2
FV-1o
Interim versions of
CLM5
POP2
CICE5
BGC
Chemistry
WACCM
Others
Begin CMIP6 simulations ~fall, 2016
All components for FV-1o frozen by Oct
FY 2016
CAM6 development (SE dycore)
Coupled simulations
CESM2
SE-1/4o
All WG meetings
Feb
Code delivery
Potential code delivery
Potential code development
Assembling and optimizing coupled model

4. CESM participation to MIPs
Diagnostic MIPs
*Interested in participating but worried about data requirements
**Participation to HighResMIP limited to AMIP simulation

5. CMIP6 DECK + Tier 1 Requirements
1o versions
CAM5: ≈12,800 years
CAM5-BGC: ≈10,500
WACCM-BGC: ≈ 7,300
Total cost: ≈150M core-hours
1/4o version
CAM5: ≈ 2,200 years
Total cost: ≈350M core-hours
1) This is only for DECK+Tier 1 while a lot of interesting science resides in Tier 2/3 experiments
2) A large factor is #years performed at high-resolution.
Mention overlap period and Rich’s talk
Yellowstone core-hours; 1 year ≈ 700M core-hours

6. Improved throughput of WACCM on Yellowstone
Figure courtesy of S. Santos and F. Vitt, with help from J. Dennis and many others
FV 1-degree 135 advected tracers: Target 8-10 simulated years per day

7. NCAR CMIP6 Planning CMIP6 Simulation CMIP6 Simulations NWSC-2
CMIP6 Analysis and Papers (will take advantage of CMIP analysis platform)
CMIP6 Data to ESGF
Ramp-up
Late Production
2018 Production
CMIP6 Post-Processing
Ramp-down
CMIP6 Simulation
CMIP6 Simulations
CESM-2 Validation
NWSC-2
Yellowstone
The thing to mention here is the nnew CMIP analysis platform for which we got funding and which will start soon, first with cmip5 data. We will also be able to take advantage of the overlap in computing power
January 2016
January 2017
January 2018
January 2019
January 2020
CESM2
Release
DOE (NERSC, Argonne); Univ. Illinois (Blue Waters)

9. Staging simulations for PI control
Ocean spin-up from Levitus (will need a few iterations)
Atmospheric chemistry simulations (with WACCM) must be performed first to generate fields necessary for all other configurations
Levitus
Land initialization
CAM w/ old forcings
CAM
Stabilized climate
Stabil.
Land initialization
Ocean BGC initialization
WACCM
This will make an unprecedented use of WACCM (with full tropospheric and stratospheric chemistry, including tropospheric and volcanic aerosols) to generate all chemical fields needed by the other versions of CESM. This has required tremendous optimization of WACCM to get a throughput of approx. 10 years per day (a joint effort by CISL/CGD/ACOM software engineer) (next slide)
Stabil.
Land initialization
Ocean BGC initialization
CAM

10. Exploring representing volcanic emission and evolution in CESM for CMIP
Volcanic emissions of sulfur are explicitly represented in CAM/WACCM through a source of sulfur dioxide (SO2). Then the model computes the chemical and microphysical evolution of the plume (here Pinatubo and later). The cimparison shows the amazing quality of the simulation of the aerosol optical depth (WACCM, black line) and the observations (green and gre, see bottom panel for 1992). This shows both the short term and long-term evolution of the volcanic plume. This has considerably improved the simulation of the climate impact of Pinatubo. It also enable to do simulations of any volcano in the past
55ºN
Mills et al., 2015