Model/Experiment Documentation Template for AMIP II 

Contact Information (to be completed by all modeling groups)

Modeling Group

AMIP Representative(s)

• Name(s) of AMIP representative(s).
• Mail address(es).
• Phone number(s).
• Fax number(s).
• Internet e-mail address(es).
• Internet World Wide Web Address, if applicable.

 

New Information for AMIP II (to be completed by all modeling groups)

Experimental Implementation

Simulation Period

• Start time (AMIP II specification: 00Z 1 January 1979).
• Stop time (AMIP II specification: 00Z 1 March 1996).

Earth Orbital Parameters

• Obliquity (AMIP II specification: 23.441 degrees).
• Eccentricity (AMIP II specification: 0.016715).
• Longitude of perihelion (AMIP II specification: 102.7 degrees).

Calendar

Recommended:

• realistic calendar with leap years in 1980, 1984, 1988, 1992, and 1996.
• vernal equinox defined as March x, where x = 20.41 - 0.0078(Y - 1987) + 0.25Y(modulo 4), Y is the year and Y(modulo 4) is the remainder after dividing Y by 4.

Radiative Boundary Conditions

• Solar constant (AMIP II specification: 1365 W/m**2).
• Solar cycles present (e.g., seasonal and diurnal cycles).
• Carbon dioxide concentration (AMIP II specification: 348 ppm).
• Ozone concentration (recommended: zonal-average monthly climatology of Wang et al. 1995).
• Concentrations of other greenhouse gases, if specified (recommended: 1650 ppbv for methane, 306 ppbv for nitrous oxide; concentrations of halocarbons such that radiative forcing = -0.24 W/m**2).
• Aerosol concentration(s), if specified (recommended: background monthly climatology only).

Ocean Surface Boundary Conditions

• AMIP II specification: Use of AMIP II sea surface temperature and sea ice boundary conditions derived by Taylor et al. (see Web document at http://www-pcmdi.llnl.gov/amip/AMIP2EXPDSN/BCS/amip2bcs.html) from observational data of Fiorino (see Web document at http://www-pcmdi.llnl.gov/amip/AMIP2EXPDSN/BCS_OBS/amip2_bcs.htm).
• Spatial interpolation procedure for use of these boundary conditions in the model (recommended: obtain from PCMDI).
• Temporal interpolation procedure for use of these boundary conditions in the model.

Orography/Land-Sea Mask

• Raw orography data set used (recommended: U.S. Navy 10' x 10' data set).
• Method of tranforming raw data to model grid, including smoothing/filtering procedures.
• Global-average value of model orography (recommended: observed value of 237.33 m).
• Procedure for deriving land-sea mask from orography data (recommended: PCMDI-supplied land-sea mask derived from U.S. Navy data set, and expressed as a percentage of land in each model grid box).
• Relevant references.

Atmospheric Mass

Spinup/Initialization

• Procedure for spin-up of the model to quasi-equilibrium at the nominal starting time of 00Z 1 January 1979.
• Initialization (at 00Z 1 January 1979) procedure for the model's
• atmosphere.
• snow cover/depth.
• soil moisture/temperature(s) (recommended: no deep infinite moisture reservoir, temperature of the deepest soil level not prescribed).
• Relevant references.

Computer/Operating System

• Computer and number of processors utilized.
• Operating system.

Computational Performance

Model Output Description

Calculation of Standard Output Variables

• Method for calculation of percentage time that a pressure surface is below ground (recommended: procedure of Boer, 1995 Mon. Wea. Rev., 114, 885-902).

• Method for calculation of monthly mean tendencies at 17 WMO standard pressure levels:
• Temperature tendency due to total diabatic heating.
• Temperature tendencies due to short-wave and long-wave radiation.
• Temperature tendency due to moist convection.
• Temperature tendency due to dry convection.
• Temperature tendency due to large-scale/stratiform precipitation.
• Total moisture tendency due to diabatic processes.

• Method for calculation of cloud properties:
• cloud water/ice (if applicable).
• extinction coefficient (cloud optical thickness/layer depth).
• cloud emittance.

• Method for calculation of surface variables (recommended: procedure of Hess and McAvaney, 1995 Aust. Met. Mag., 44, 139-145)
• 10 m winds
• 2m specific humidity
• 2m temperature

• Method for calculation of mean sea-level pressure (recommended: ECMWF algorithm--code to be provided by PCMDI).

• Method for calculation of clear-sky radiation and cloud radiative forcing (recommended: procedure of Potter et al., 1992 J. Geophys. Res., 97, 20507-20518).

• Method for calculation of potential vorticity, if supplied (recommended: procedure of Hoskins et al., 1985 Quart. J. R. Met. Soc., 111, 877-946).

• Method for calculation of planetary boundary layer height, if supplied (recommended: see Holtslag and Boville, 1993 J. Climate, 6, 1825-1842 and Vogelezang and Holtslag, 1996 Bound. Layer Met., 81, 245-269).

Sampling Procedures

• Sampling procedure for calculation of monthly means of standard output variables (e.g., accumulation over every model time step vs accumulation of 6-hourly averages). Recommendations: See the AMIP II Guidelines: Appendix A Table Notes (at Web address http://www-pcmdi.llnl.gov/amip/NEWS/amipnl8.html#Appendix-A)for variable-dependent sampling procedures.
• Relevant references.

Interpolation Procedures

• Algorithm for interpolation of standard output variables to 17 WMO pressure surfaces (e.g., monthly averages computed in model coordinates, then interpolated to constant pressure surfaces vs monthly averages computed in model coordinates weighted by time varying mass on the 17 WMO pressure surfaces).
• Algorithm for treatment of variables on pressure surfaces below ground (if applicable). Recommended: ECMWF algorithm, if below-ground values are calculated--code to be provided by PCMDI.
• Relevant references.

Output Data Structure/Format/Compression

• Structure/format of output data (AMIP II specification: LATS structure in either NetCDF or GRIB format).
• Original and compressed word length of data (in bits per word) and description of compression algorithm.
• Relevant references.

Model Characteristics

AMIP II Model Designation

Example: NCAR CCM3 (T42 L18) 1997

Model Lineage

• Predecessor model(s) from which the AMIP II model is descended, and the major changes made in the former in order to arrive at the latter.
• Designation of most similar model documented for AMIP I--see summary documentation at World Wide Web address

http://www-pcmdi.llnl.gov/projects/modeldoc/amip/01toc.html

Example: NCAR CCM2 (T42 L18) 1992

Differences From Most Similar AMIP I Model (to be completed as needed)

Note, for each of the following model properties, only differences from the most similar AMIP I model need be described--you may omit mention of properties that are the same. Please cite references (including information on author(s), year, title, journal name/report series number, volume number, and page numbers) wherever these are relevant to describing a particular model difference. For guidance, consult the current AMIP I model summary documentation at World Wide Web address

http://www-pcmdi.llnl.gov/projects/modeldoc/amip/01toc.html

Model Documentation

Numerical/Computational Properties

Horizontal Representation

• Formulation of horizontal variation of model variables (e.g., second-order finite differences on a C grid, spectral basis functions with transformation to Gaussian grid, etc.).
• Variable-dependent differences in formulation, if present (e.g., spectral dynamical variables vs semi-Lagrangian grid-point water vapor and chemistry).

Horizontal Resolution

• For finite difference horizontal representation, grid spacing in degrees latitude-longitude.
• For spectral horizontal representation, triangular or rhomboidal resolution (e.g., T42, R31, etc.) and rough resolution of the Gaussian grid in degrees latitude-longitude.
• Relevant references.

Vertical Domain

• Model top in units of hPa.
• Pressure of lowest atmospheric level (in hPa) when surface pressure is 1000 hPa.

Vertical Representation

• Vertical coordinates (e.g. sigma, modified sigma, hybrid, etc.).
• Vertical differencing scheme, conservation constraints if any.
• Relevant references.

Vertical Resolution

• Total number of vertical levels.
• Number of levels below 800 hPa and above 200 hPa for a surface pressure of 1000 hPa.

Time Integration Scheme(s)

• Type of scheme used for time integration.
• Explicit vs (semi-)implicit scheme.
• Corrector steps, method of damping computational mode, etc.
• Time filter, if any.
• Time step length for dynamics vs physics, frequency of recalculating radiative fluxes.
• Relevant references.

Smoothing/Filling

• Method of
• smoothing orography and/or other fields.
• filling spurious negative moisture values.
• correcting nonconserved quantities (atmospheric mass, etc.).
• Relevant references.

Dynamical/Physical Properties

Equations of State

• Variables used to define model history of state.
• Prediction equations and framework (e.g., primitive equations in a spectral Eulerian framework for dynamics, in a grid-point semi-Lagrangian framework for water vapor and chemistry).
• Relevant references.

Diffusion

• Representation of horizontal diffusion:
• variables to which applied and variable-dependent differences in application (e.g., diffusion of moisture treated by semi-Lagrangian formulation).
• linear vs nonlinear.
• numerical order (e.g., second-order or del-squared).
• variation in application according to height, horizontal resolution.
• application on constant sigma surfaces, pressure surfaces, etc.
• Representation of vertical diffusion above the surface layer:
• variables to which applied and variable-dependent differences in application.
• dependence on stability and/or height.
• local vs nonlocal.
• linear K-theory or another approach (e.g., prognostic turbulence kinetic energy scheme).
• Relevant references.

Gravity Wave Drag

• Description of gravity wave drag parameterization.
• Relevant references.

Chemistry

• Enumeration of radiatively active gases (CO2, ozone, water vapor, other trace gases) and aerosols.
• Description of main properties (diagnostic vs prognostic ozone, concentrations, temporal dependence, distributions--globally uniform, zonal mean, 3-D).
• Algorithm for chemistry transport, if present (e.g., grid-point semi-Lagrangian transport of water vapor, and on option, chemical tracers).
• Relevant references.

Radiation

• Treatment of clear-sky shortwave radiation, including number and boundaries (expressed in microns) of spectral bands.
• Treatment of clear-sky longwave radiation, including number and boundaries (expressed as wavenumbers in m^-1) of spectral bands.
• Treatment of interactions with clouds, including dependence of shortwave/longwave optical properties on (prescribed, diagnostic, or prognostic) cloud liquid water; cloud vertical overlap assumptions for radiation calculations (e.g., full vs random overlap).
• Treatment of interactions with aerosols, if present.
• Relevant references.

Convection

• Treatment of penetrative (deep) convection.
• Treatment of shallow convection.
• Relevant references.

Cloud Formation

• Treatment of stratiform cloud (e.g., prognostic vs diagnostic, cloud types considered, cloud fraction determination, height-dependence)
• Treatment of sub-gridscale convective cloud
• Relevant references.

Precipitation

• Criterion for large-scale precipitation formation (including whether method is diagnostic or prognostic).
• Criterion for convective precipitation formation (including whether method is diagnostic or prognostic).
• Treatment of evaporation of falling large-scale and/or convective precipitation.
• Sub-gridscale distribution of precipitation over land, if applicable.
• Relevant references.

Planetary Boundary Layer

• Treatment of PBL (e.g., K-theory, nonlocal diffusion, prognostic turbulence kinetic energy (TKE) scheme, etc.).
• Determination of PBL top (e.g., prognostic scheme, stability-dependent algorithm, assumed sigma level, etc.).
• Relevant references.

Sea Ice

• albedo and emissivity, total depth and number/thickness of discrete layers, surface and interior temperatures.
• if applicable, effects of snow on sea ice (e.g., impacts on ice thickness, , roughness length, thermodynamics, etc.).

Snow Cover

• Criteria for formation, accumulation, and melting of prognostic snow (or citation of data set for prescribed snow cover/depth). Value of snow density for conversion of snow mass to water-equivalent snow depth.
• Number of snowpack layers and method of calculating their temperatures and freezing/melting rates.
• If applicable, method of calculating sublimation to surface evaporative flux.
• If applicable, algorithm for (sub-gridscale) fractional snow cover.
• If applicable, effects of snow cover on surface thermal properties and/or roughnesses.
• Relevant references.

Surface Characteristics

• Distinguished surface types (i.e., ocean, sea ice, continent, bare and vegetated ground, continental ice, etc.).
• If applicable, number of vegetation and/or soil types (with citation of relevant data sets).
• Roughness lengths for momentum fluxes over distinguished surface types and, if different, roughness lengths for surface heat/moisture fluxes  (with citation of relevant data sets or relationships). Dependence of roughness lengths on ocean surface wind stress, snow cover, etc.
• Specification of surface albedo for distinguished surfaces and method of obtaining grid-box bulk value. Dependence of albedo on snow cover, soil moisture, solar zenith angle/wavelength, etc.
• Specification of longwave emissivity for distinguished surfaces and method of obtaining grid-box bulk value. Dependence of emissivity on soil moisture, snow cover, etc.
• Relevant references.

Surface Fluxes

• Treatment of surface shortwave/longwave radiative fluxes (e.g. method of aggregating radiative fluxes over distinguished surfaces for computing bulk grid-box values).
• Treatment of turbulent eddy fluxes of surface momentum, heat, and moisture (e.g., Monin-Obukhov similarity theory implemented by the method of...).
• Dependence of turbulent drag coefficients on stability, roughness, etc. If applicable, specification of different neutral drag coefficients for heat, moisture, momentum.
• Number/types of surface resistances in the formulation of surface evaporation/transpiration (e.g. resistances associated with unsaturated soil, leaf stomates, vegetation canopy, etc)  and their dependences on radiation, temperature, humidity, soil moisture, vegetation rooting, etc.
• If evaporation/transpiration from vegetation is explicitly represented: specification of: active soil depth (root zone) for transpiration, and  its spatio-temporal variation (with citation of relevant data sets).  Method for determining bulk grid-box evaporation (e.g. "big leaf" vs. "mosaic" approaches, etc.).
• If a vegetation canopy is explicitly represented, : number/types of canopy levels; determination of holding capacity for intercepted precipitation; treatment of  resistance to evaporation/transpiration (e.g. aerodynamic/biophysical processes represented, spatio-temporal variation of unstressed stomatal resistance, etc.).
• If applicable, method of predicting surface fluxes of carbon and/or other chemical constituents.
• Relevant references.

Land-Surface Processes

• Name/acronym of the land-surface scheme (e.g. as used in the Project for Intercomparison of Landsurface Parameterization Schemes experiments).
• Method of computing soil surface temperature versus skin temperature (if different), and temperature of vegetation canopy (if represented). Treatment of soil heat storage (ground heat flux) and soil heat capacity/conductance. Dependence of thermodynamics on soil water/ice and snow cover.
• Number and thickness of soil layers for computing heating. Method of determining  vertical distribution of soil temperature (e.g.zero-storage, heat diffusion, force-restore, etc.).  Lower boundary condition for soil heating/temperature (e.g. zero-flux condition versus prescribed temperature--if the latter, determination of spatio-temporal variation of boundary temperature, with citation of relevant data sets).
• Number and thickness of soil layers for moisture.  Method of computing vertical distribution of soil water/ice. Lower boundary condition for soil hydrology (e.g. zero flux, constant flux, constant head, etc.--if not zero flux, method of calculating the lower boundary condition).
• If relevant to the land-surface scheme, methods for determining:  saturated hydraulic conductivity/soil water content; actual hydraulic conductivity; wilting point and field capacity (with citation of relevant data sets). Conditions (if any) under which soil moisture may drop below field capacity, and its minimum allowed value.
• If relevant for the land-surface scheme, methods for determining:  surface runoff; drainage at the base of the soil column; interior lateral flow (note absence of any of these runoff types).  Method for determining threshold soil moisture for which drainage ceases. If soil moisture recharge (from below) is represented, conditions for which this process is triggered.
• Relevant references

UCRL-MI-126432