Documentation of the PMIP models (Bonfils et al. 1998)


PMIP Documentation for MSU

Moscow State University, Department of Meteorology and Climatology: Model MSU (10x15L3), Version of the 1989 year.



PMIP Representative(s)

Mr. Alexsandre Kislov, Dep.of Meteorology and Climatology, Moscow State University, Geographical Faculty, Moscow, Russia, 119899, Phone: 095 9392942, Fax: 095 9328836, email: kislov@gis.geogr.msu.su
 

Model Designation

MSU (10x15L3) 1994
 

Model Identification for PMIP

MSU
 

PMIP run(s)

0fix, 6fix, 21fix

JJA and DJF ('perpetual' conditions)
 

Model Lineage

The MSU model was developed in 1989 for climate applications. The latest version of this model is significantly differ from first version:

a) it is used the simulation with seasonal resolution

b) it is used the limited area model nested in global model (so called MSU & LAMBLS )

c) it is used more comprechensive surface scheme (looks like as Sib, but using subgrid information about vegetation cover within each grid box), including explicit description of the thermal regime of the large lakes

d) it is used more comprechensive parameterization of the snow cower
 

Model Documentation

the Russian magazines: 1) Izvestiya, Atmospheric and Oceanic Physics 2) Meteorology & Hydrology, N 3 were translated in English and they can be accessible. I do not represent the information about pages of the article because the pages of the translated text are differ from pages of the Russian issues.

main reference:

Kislov A.V. (1991), Three-dimensional model of atmospheric circulation with complete description of physical processes and simplified dynamics, Izvestiya, Atmospheric and Oceanic Physics, Vol.27, N 4 /English Translation/

secondary reference(s) :

Kislov A.V. (1993), A simulation of the climate of Holocene's optimum, Izvestiya, Atmospheric and Oceanic Physics, Vol.29, N 2 /English Translation/ Kislov A.V. (1993) Investigation of genesis of cold ivents during late glaciation (using Dryas-3 as an example) Izvestiya, Atmospheric and Oceanic Physics, Vol.29, N 2 /English Translation/

Kislov A.V. (1993), Character of monsoon circulation during some periods of paleotime. Meteorology & Hydrology, N 3

Kislov A.V. (1994), Study of forming factors in the warm climates of Holocene based on simplified general circulation model simulations, Izvestiya, Atmospheric and Oceanic Physics, Vol.30, 353-361 /English Translation/

Kislov A.V. (1994) Study of the genesis of the global climate fluctuations during postglaciation, Izvestiya, Atmospheric and Oceanic Physics, Vol.30, 353-361 /English Translation/

Kislov A.V., G.V.Surcova (1997), The use of a limited area model for the estimation of variation in evaporation minus precipitation from the Caspian Sea during the Holocene Izvestiya, Atmospheric and Oceanic Physics, Vol.33, N 1 /English Translation/

Kislov A.V., G.V.Surcova (1998), The simulation of the Caspian Sea level changes during last 20,000 years. In Palaeohydrology and the Hydrological Sciences, Edited by G.Benito, V.R.Baker and K.J.Gregory, John Wiley & Sons,Ltd. /To be published/
 

Numerical/Computational Properties

Horizontal Representation

The finite difference mesh of the model has a spacing between grid points of 10 latitude and 15 longitude.
 

Horizontal Resolution

10 x 15 degrees latitude-longitude.

dim_longitudexdim_latitude: 24x17
 

Vertical Domain

Surface to 100 hPa. Pressure of lowest atmospheric level is 900 hPa when surface pressure is 1000 hPa.
 

Vertical Representation

The model has 3 levels in the vertical direction. The model uses P-coordinate.
 

Vertical Resolution

There are the following levels: 900, 600, 250 hPa.
 

Computer / Operating System

The PMIP simulation was run on PC-486.
 

Computational Performance

For the PMIP, 0.1 minutes PC-486 computation time per simulation 1 day.
 

Initialization

The model was started from a intial conditions based on dry, unmoveable atmosphere. Snow cover boundary are prescribed based on climate scenario (the present day, 6 or 21 ka). Temperature of the deepest soil level are not prescribed.
 

Time Integration Scheme(s)

A implicit time integration scheme is used. The time step is 24 hours for all dynamics and physics fields.
 

Smoothing/Filling

Orography is represented on grid-poin mesh 10x15 deg. Negative values of atmospheric specific humidity (which arise because of numerical errors in the discretized moisture equation) are made slightly positive by borrowing moisture (where possible) from other layers in the same column. If column moisture is insufficient, a nominal minimum bound is imposed, the moisture deficit is accumulated over all atmospheric points, and the global specific humidity is reduced proportionally.
 

Sampling frequency

I have the output without sampling procedure.
 

Dynamical/Physical Properties

Atmospheric Dynamics

A simlified (a quasigeostrophic scheme similar to Sellers (1983)) equations are expressed in terms of temperature, specific humidity and wind components. Effects of synoptic-scale eddies on transfer of the energy, moisture and momentum have been parameterized. Divergence are calculated based on geostrophic vorticity (Gill, 1982).
 

Diffusion

Horizontal diffusion follows the scale-dependent eddy viscosity. Second-order vertical diffusion of moisture and heat operates within the boundary layer depends on stability and the vertical shear of the wind, following standard mixing-length theory. Diffusivity for moisture is taken to be the same as that for heat.
 

Gravity Wave Drag

Gravity wawes are excluded by geostrophic approach.
 

Radiative Boundary Conditions

The solar constant is 1367 W/(m2). The orbital parameters and seasonal insolation's distribution are calculated after PMIP recommendations. 'Perpetual' JJA and DJF are simulated.
 

Chemistry

The carbon dioxide concentration is the prescribed value of 300, 280 and 180 ppm for 0fix, 6fix 21fix run, respectively. A monthly globally averaged ozone distribution is specified. Radiative effects of water vapor also are treated. Radiative effects of aerosols are treated for solar fluxes calculation.
 

Radiation

Upward/downward shortwave irradiance profiles are evaluated using integral function of transmittance (Feigelson, 1978) taking into account clouds, aerosols and gases. Shortwave/longwave optical properties of the clouds is expected can be parameterized in terms of air temperature and precipitation rate.

Upward/downward longwave radiation profiles are evaluated using integral function of transmittance (Feigelson, 1970) taking into account clouds and gases. Clouds at the middle and low levels are treated as blackbodies. Clouds at the high level are treated as graybodies, with emissivity depending on optical depth.
 

Convection

A moist convective adjustment procedure is applied on pairs of vertical layers whenever the model atmosphere is conditionally unstable. Convective instability occurs when the local thermal lapse rate exceeds a critical value, which is determined from a weighted linear combination of dry and moist adiabatic lapse rates, where the weighting factor is a function of the local relative humidity. Convective instability may occur in association with condensation of moisture under supersaturated conditions, and the release of precipitation and associated latent heat.
 

Cloud Formation

The fractional cloud cover in a vertical layer is computed from a linear function of the relative humidity of the air (Smagorinsky's relations). Clouds at the high level is expected to appear if moist convection is realized (typically for ITCZ conditions) or if wind speed at this level excess above a threshold value. The threshold allows to take into account the fact that in extratropical regions the fields of cirrus clouds are formed near the jet position.
 

Precipitation

Precipitation is simulated whenever supersaturation is indicated by the prognostic equation for water vapor. There are two types of precipitation: large-scale precipitation and convective precipitation. Part of precipitation can be evaporated in situ.
 

Planetary Boundary Layer

The depth of the PBL is not explicitly determined, but in general is assumed that it centered at the lowest prognostic vertical level (980 hPa). Within the PBL convective adjustment takes place, which simulates boundary-layer mixing of heat and moisture, and by enhanced vertical diffusivities. Within the PBL the surface boundary layer is situated, its temperature and moisture required for calculation of surface fluxes are calculated using standard K-theory procedure.
 

Orography/Land-Sea Mask

Orographic heights with a resolution of 1 deg. on a latitude/longitude grid are smoothed by linear averaging over 10x15 degree grid boxes.

It was used the same spatial land/sea distribution for the run at 0k and 21k , but at 21k the height of the ice sheets took into account it was added to orography height for 0k.

I used the ice sheet reconstructions of Peltier et al. (1994).
 

Ocean Surface Boundary Conditions

For 0fix: monthly averaged modern climatological SSTs based on : NOAA Atlas NESDIS 4, World Ocean Atlas 1994, Volume 4: Temperature, Washington, D.C., U.S. Dept.of Commerce, S.Levitus, T.P.Boyer.

For 6 fix: same as for 0fix.

For 21 fix: The CLIMAP (Last Glacial Maximum) data was used.
 

Sea Ice

Sea ice distribution was prescribed corresponding on modern data (0fix,6fix) and CLIMAP (21 fix). The surface temperature of the ice is a prognostic function of the surface heat balance and of a heat flux from the ocean below.
 

Snow Cover

Snow cover was prescribed field. Snow cover affects the surface albedo of land and of sea ice, as well as the heat capacity of the soil.
 

Surface Characteristics

The 5 x 7.5-deg. data on natural zones types are used to determine surfase parameters (albedo, thermal conductivity, thermal diffusivity, depth of the active layer of the soil (in permafrost region), moisture availability factor). The local land albedo also depends on the fractional snow cover the resulting albedo is a linear weighted combination of snow-covered and snow-free albedos. Over the oceans, latitude-dependent albedos cover the range between 0.06 and 0.17. The longwave emissivity is prescribed as unity for all surfaces.
 

Surface Fluxes

The surface solar absorption is determined from surface albedos. The surface turbulent eddy fluxes of heat and moisture are expressed as bulk formulae following Monin-Obukhov theory. The fluxes of latent and sensible heat is a product of a neutral transfer coefficient, the surface wind speed, the difference in temperatures (or specific humidity) between the surface and that of the top surface boundary layer. Formulae for latent heat flux over land includes the moisture availability factor.
 

Land Surface Processes

Soil heat storage is determined as a residual of the surface heat fluxes. Soil temperature is computed from this heat storage in a single layer, following the method of Kislov (1991). The soil parameters in each grid box is computed as a function of natural zone type, soil moisture, and snow cover. Soil moisture in 'perpetual' experiments is prescribed.

Last update November 9, 1998. For further information, contact: Céline Bonfils (pmipweb@lsce.ipsl.fr )