What's New in CESM1.2.0 - Software
The CESM1.2 release has numerous new key features among which are the addition of CLM4.5, new science changes to CAM5 running with the CAM-SE dynamical core, and new scripting infrastructure for the generation of component sets, grids and model testing.
Additional information regarding these updates is also available in the CESM User's Guide and in the individual model component documentation.
General Updates for Specifying Component Sets (compsets) and Resolution Grids
CESM1.2.0 provides a completely new way to generate component sets and grids that also allows for backwards compatiblity with older compsets. A complete list of supported compsets and resolution grids are specified using an XML schema that is described with the complete lists in the documentation.
These are the notable improvements associated with the CAM5.3 model in CESM1.2.0
- CAM-SE now uses vertically Lagrangian advection by default
- Option for prescribed modal aerosols is available for pre-industrial and present day climatology simulations
- Optional MG1.5 refactored microphysics (scientifically similar to MG1.0 which is still default, except for a feature change to activation)
- The size of the default history file output has been significantly reduced
- Many bug fixes including:
- WACCM fixes (see WACCM section)
- prevented crashes due to bad saturation vapor pressure values at low pressure and/or high temperature
- dust emissions
- spectral element dy-core updates
The new features available in CAM-Chem in this release include:
- coupling of tropospheric and stratospheric chemistry with the CAM5 modal aerosol model 3 and 7
- expansion of the representation of secondary-organic aerosols
- implementation of MEGAN v2 in CLM, including a flexible framework for assigning MEGAN emissions to species represented in the chemistry.
All these are released to give users access to these new capabilities. Only limited evaluation has been performed.
Functional updates for WACCM include:
- New compsets for WACCM4 with CARMA sectional microphysics code for aerosols:
- BNUKE_C4WBC_L40CN - Stratospheric black carbon for nuclear winter studies (RCP4.5, functional)
- FGEOS_C4WSF_L40CN - Stratospheric sulfate coupled to heterogenous chemistry, nudged by specified dynamics (SD-WACCM, functional)
- WACCM spectral element (SE) dycore support (functional)
- Updates and bug fixes for specified chemistry (SC-WACCM, functional)
- ozone file fixed
- Updates for specified dynamics (SD-WACCM and SD-CAMchem, functional)
- SSI/TSI and Kp files updated for 2012
- SPE and SAD file updates for 2012 to be created
- new namelist specification for nudging factor (time scale, rather than percent)
- WACCM5 updates and bug fixes (functional)
- Chemistry updates in waccm_mozart (functional)
- Remove obsolete waccm_mozart_v1 chemistry package
- New version of Glimmer-CISM (version 1.9). This version includes extensive modifications that have been made in preparation for the upcoming release of Glimmer-CISM version 2.0, which will include 3d, 1st-order-accurate ice dynamics and support for MPI-based distributed parallelism. When run with shallow-ice dynamics, Glimmer-CISM 1.9 gives answers that are approximately the same as version 1.6, which was the version included in CESM1.1.1 and earlier.
- New default parameter values (temp_init, basal_mass_balance, and sigma)
- New initial conditions have been provided for both CLM and CISM, when running the BG1850CN compset at f09 resolution. For the first time, this includes spun-up ice sheet initial conditions.
- Option to run with 36 elevation classes (200m each)
- The GLC_GRID xml variable has been renamed to CISM_GRID
For more details on the changes made in CESM1.2.0, see the "What's new in CESM1.2.0" section of the CISM documentation.
- New CLM4.5 science: (supported for I compsets only for only: f09, f19, hcru resolutions)
- PTCLM is working again.
- Code allows switch between CLM4.0 and CLM4.5
- Revised canopy integration, canopy scaling, co-limitation of photosynthesis, multilayer canopy option, temperature acclimation, iterative calculation fix (Bonan et al., 2011, 2012; Sun et al., 2012)
- CENTURY-like vertically resolved soil biogeochemistry (CLM4.5BGC: Koven et al., in prep)
- Cold region hydrology updates including impedance factor and perched water table (Swenson et al. 2012)
- Revised snow cover fraction parameterization and separate energy calculations for snow covered and snow free portion of gridcell (Swenson and Lawrence, 2012)
- RTM: 2-way CLM/RTM interactions, flooding (default off) (Swenson and Lawrence, in prep)
- RTM: Variable river flow velocity based on slope
- New lake model (Subin et al., 2012)
- CH4 emissions (Riley et al., 2011; Meng et al. 2012)
- Prognostic wetland distribution model (Swenson and Lawrence, in prep)
- Revised fire model including anthropogenic triggers and fire suppression and agricultural and deforestation fire (Li et al., 2012, 2013)
- Interactive fertilization, irrigation, organs pool, and other updates to crop model (Drewniak et al., 2013; Levis et al., 2012; Sacks et al. 2009)
- VIC hydrology (alternative optional hydrology) (Li et al., 2012)
- C13/C14 enabled
- Multiple urban density classes
- C3 Arctic grass and Arctic shrub phenology switched from stress to seasonal deciduous
- Default glacier bare ice albedo changed
- Multiple minor bug fixes
- Faster and more streamlined carbon cycle spinup capability
- DATM -- Add support for using CRUNCEP forcing for CLM.
Driver update include:
- added support for WAV model (see below)
- cart3d mapping will be default for all resolutions
- patch mapping for wind fields from atm->ocn will be default (new mapping files)
- removal of 1.e-6 scaling factor for epbal in pop/drv
Updates to the POP ocean model include:
- Support for new decompositions (no longer limited to pop_decomp.xml)
- Improved communication in overflow module (replacing global reductions with local messages)
- Significant updates to te ocean ecosystem
- Bugfix: the diagnostic variable RHO_VINT was being computed incorrectly.
- added support for multi-instance runs
- added functionality to set simyr and finidat_rtm files
- added r05 resolution for 1850/2000
- now use SLOPE and MAX_VOLR in r05 direction files
- introduced initial condition files for 1850/2000
- sending VOLR as diagnostic field to CLM (also effects TWS)
- introduced rtm_active and flood_active controls
- added rtm_effvel velocity to be backward compatible with clm4_0_* tags
- added RTMTHRESH and RTMFLOOD to history output
CAM-CHEM and WACCM scripts changes and Component Sets
CESM1.2.0 introduced the following scripts changes for CAM-CHEM and WACCM:
- added new F_2000_STRATSOA (FSTRATSOA) compset
- removed F_TROP_STRAT_CHEM_CN
- changed reference to "waccm_mozart_v1" to "waccm_mozart"
- set CCSM_CO2_PPMV to 0.000001 for all *_WACCM, *_SD, *_MOZART, _MOZSOA, *_STRAT* compsets
- turned off "CN" for compset FMOZSOA
- configured FMOZSOA compset with cam4 phys
- added age-of-air tracers to *_MOZMAM, *_MOZSOA, *_STRATMAM* compsets
- set CICE_NAMELIST_OPTS="cam5=.true." for *_STRATMAM*, *_MOZMAM compsets
- the hybrid startup type set up for B_1850_WACCM5_CN needs a 70-level CAM IC file
- new build-namelist use_case files for compsets *_MOZMAM, *_MOZSOA, *_STRATMAM*
CESM build support for aquaplanet outside of CAM
The following five configurations can now be built using the CESM build scripts:
- F_2000_CAM4_AQUAPLANET - CAM 4 physics in aquaplanet mode
- F_2000_CAM5_AQUAPLANET and F_AQUAPLANET - CAM 5 physics in aquaplanet mode
- F_IDEAL_PHYS - CAM ideal physics
- F_ADIAB_PHYS - CAM adiabatic physics
Tools / Mapping
Updates to the tools and mapping capabilities include:
- New version of ESMF on yellowstone allows computation of nearest-neighbor maps.
- The new map_field tool takes a map, a data set [on source grid], and a variable name as input and produces the field on the destination grid as output.
- Bugfix: tools now all build / run on yellowstone.
CESM1.2.0 introduces a new WAV model to CESM with initial support of just the stub and dead versions for this release.