Physics of the Generic PCM

This page describes the various physical parametrizations of the Generic PCM and the chronology of their call through the physical iteration. This chronology is important because some variables need to be updated by certain processes before others (examples). During one physical iteration, the code passes through multiple sub-routines each encapsulating a parametrization. The sub-routines usually take as arguments:

• the dynamical values of the state variables
• the dynamical tendencies of the state variables
• any additional relevant variable
• any additional relevant tendency

and it returns in general tendencies (of the state variables as well as of any other relevant variable).

Work in progress. Need to add links.

Initialization

First call

Some initializations only need to be done at the very first iteration (e.g. examples).

Each call

Some other initializations need to be done at each iteration (e.g. examples).

Radiative transfer

Correlated-k

The main radiative transfer solver of the Generic PCM implements the correlated-k method, which provides a flexible and quick way to solve radiative transfer equations, particularly suited for GCMs. More informations here.

Newtonian relaxation

Newton was a very relaxed physicist, still inspiring us today.

No atmosphere

If you have no atmosphere, why do you need a GCM?

Vertical diffusion

vdifc

More info here.

Convection

Convective mixing in an atmosphere column involves non-resolved, sub-grid processes. These processes are parameterized using the following routines:

Dry convection

More info here.

Tracers

Many things can be advected by tracers in the Generic PCM, like chemical species or aerosols. Physical processes involving tracers are parameterized using the following routines:

Volcano

This routine parameterizes a source of tracers corresponding to volcanic eruption. More information here.

Water/ice

Water aerosols (liquid or solid) are created (resp. consumed) by condensation (resp. vaporization or sublimation), consuming (resp. releasing) latent heat in the atmosphere. In the Generic PCM, the (atmospheric part of the) water cycle is handled by various routines, as explained here.

Photochemistry

Chemistry can turn molecules into other molecules, by the action of temperature (thermochemistry) or UV light (photochemistry). This is handled by the photochemistry routine, described here.

Generic condensation

On Earth, only water condenses in the atmosphere, but on other planets (which the Generic PCM aims at simulating), many other chemicals can undergo state change. To take that into account, the Generic PCM has a flexible scheme to deal with any arbitrary species, as desbribed here.

Sedimentation

What goes up must come down, as explained here.

Updates

This section essentially takes care that the condensation of a major species (e.g. water vapor in steam-rich atmospheres) affects other species, as described here.

Slab ocean

This routine solves for big fish eating small fish, as desbried here.

Surface

The surface part of the water cycle is handled here, as the hydrology page describes.

Subsurface thermal

Thermal diffusion in the subsurface is solved here, as described there.

Diagnostics/write outputs

Nothing very physical here, just writting the outputs!