SURFEX

Surface assimilation

2016-05-03T08:53:41Z

Assimilation of near-surface and remotely sensed variables are performed using two assimilation techniques :

The OI scheme allows to correct soil moisture contents and soil temperatures from the knowledge of short-range forecasts errors in temperature and relative humidity at 2 meters. Analytical OI coefficients have been derived from Monte-Carlo single column experiments in clear-sky situations and need to be reduced when near-surface atmospheric errors are not informative about errors in the soil variables.

The EKF scheme allows the assimilation of the same variables, but in addition is able to assimilato satellite derived superficial soil moisture observations from the radiometer AMSR-E/Aqua. Regarding land surface monitoring, the EKF has been used to assimilate jointly the Leaf Area Index and superficial soil moisture measurements in the ISBA-Ags version where biomass reservoirs are prognostic variables

Chemistry and aerosols

2016-05-03T08:53:17Z

SURFEX is able to evaluate using several models and parameterisations :

Emission parameterizations :

The dust fluxes are calculated using the Dust Entrainment And Deposition (DEAD) model (Zender et al. [2003])
Sea Salt emission are parameterized upon the formulation of Vignati et al. [2001] (effective source function) or upon a lookup table defined by Schulz et al. [2004].

Deposition parameterizations :

Dry deposition is usually parametrized through a deposition velocity
Dry deposition and sedimentation of aerosols are driven by the Brownian diffusivity and by the gravitational velocity

Tile Lakes

2016-05-03T08:52:55Z

Surface fluxes over ocean and sea can be parameterized using either simple or more elaborated parameterisations :

Simple parameterizations :

All prognostic variables are kept constant and the roughness lentgh is given by the Charnocks formula.
If the surface temperature is below 271.15 K, the water is assumed to be covered by ice. Flux claculations are performed using the roughness lenght of flat snow surfaces, the sea-ice albedo is assumed to be equal to the fresh snow albedo.

FLake model

The FLake model can be used within SURFEX. FLake is a freshwater lake model capable of predicting the vertical temperature structure and mixing conditions in lakes of various depth on time scales from a few hours to many years. The model is intended for use as a lake parameterisation scheme in numerical weather prediction, climate modelling, and other numerical prediction systems for environmental applications. FLake can also be used as a stand-alone lake model, as a physical module in models of aquatic ecosystems, and as an educational tool.
More details on the FLake web site

Tile Sea and Ocean

2016-05-03T08:52:26Z

Surface fluxes over ocean and sea can be parameterized using either simple or more elaborated parameterisations :

Simple parameterizations :

All prognostic variables are kept constant and the roughness lentgh is given by the Charnock's formula.
If the surface temperature is below 271.15 K, the water is assumed to be covered by sea ice. Flux claculations are performed using the roughness lenght of flat snow surfaces, the sea-ice albedo is assumed to be equal to the fresh snow albedo.

Iterative calculation of surface fluxes

Several parameterization for surface fluxes are available. They are based on past experimental campaigns and take into account the effect of atmospheric convection, precipitation and gustiness on fluxes.

1D oceanic mixing layer model

The 1D model includes a prognostic equation for the turbulent kinetic energy (e) with a 1.5 order closure. The other prognostic variables are the temperature (T), the salinity (S), and the current [U = (u, v)].
The 1D oceanic model allows to have variable surface variables.

Tile Nature

2016-05-03T08:51:59Z

ISBA (Interaction Sol-Biosphère-Atmosphère) is a land surface model interfaced with atmospheric and hydrological models. ISBA is developed by CNRM in collaboration with various research teams.

ISBA includes several modules simulating transfers of heat, water, carbon and other components in the soil, vegetation, snow. It has many options for each of the submodels.

Soil submodel :

Force restore, two soil layers (temperature, water and ice)
Force restore, three soil layers (temperature, water and ice)
Multilayer soil (temperature, water and ice)

Vegetation submodel :

Noilhan and Planton (1989) Jarvis options
A-gs, photosynthesis and CO2 fluxes
A-gs, photosynthesis, CO2 fluxes and interactive vegetation

Hydrology submodel :

No subgrid hydrology
subgrid surface runoff
subgrid drainage

Snow submodels :

1 layer, variable albedo and density (Douville et al., 1995, Bazile)
3 layers, Explicit Snow, intermediate complexity, albedo, density, liquid water (Boone et Etchevers, 2002)
multilayer detailed snow model CROCUS

How to begin with SURFEX ?

2014-03-05T12:03:18Z

Get the code

The code is available in the code download section. This section offers download of the last versions.
If you plan to work on model development, cooperate with a developer, or need access to version in development, you may want to access the code on the GIT repository.

Install, compile and first runs

Go on the section dedicated to installation and compilation, where these steps are described (also at the beginning if the user's guide)

Consult the documentation :

The most useful parts for beginners are :

installation and compilation
User's guide (namelists documentation)
Scientific documentation
The code browser
The versions informations (changes from one version to another)

Download of physiography, orography databases

Go to Physiography download