View source for CO2 Condensation (Generic PCM)

This page describes the condense_co2 routine of the Generic PCM. This routine, inherited from the Mars PCM, only works for atmosphere where CO2 is the background, dominant gas. If CO2 is a trace, variable gas, you should use the [[Radiative_Generic_Condensable_Specie|generic condensation scheme]].

= Nucleation and Condensation of CO2 =
The condensation and nucleation temperature are calculated using Fanale's formula (subroutines '''get_tcond_co2''' and '''get_tnuc_co2'''):
\begin{equation}
	T_{\rm cond}=
        \begin{cases}
                     \frac{-3167.8}{\log(0.01\times P)-23.23}    & {\rm if }P<P_{\rm triple}=518000~{\rm Pa}\\
                     684.2-92.3\times\log(P)+4.32\times\log(P)^2 & {\rm otherwise}
        \end{cases}
\end{equation}
At the moment, we consider $$T_{\rm nuc}=T_{\rm cond}$$.

= In the atmosphere =

The routine iterates condensation and sedimentation in the atmosphere column over 20 subtimesteps. It computes:

== Sedimentation of CO2 aerosols ==

Using the subroutines '''co2_reffrad''' for the aerosols particles radius, the Stokes velocity is calculated with subroutine '''stokes''' and the tracers are updated using subroutine '''vlz_fi'''.

== Condensation and sublimation of CO2 in the atmosphere ==
If the local temperature is below the nucleation temperature or CO2 ice is present, condensation / sublimation tendencies for CO2 tracers (ice and gas) as well as temperature (via latent heat effect) are calculated.

= On the ground =

== Condensation and sublimation on the ground ==
Surface tracer and temperature tendencies due to condensation or sublimation at the surface as well as CO2 ice accumulation on the ground due to icefall are then calculated. Importantly, surface pressure is adjusted to account for variations in CO2 ice cover.

== Albedo and emissivity ==
Finally, albedo and emissivity are re-calculated as a function of the amount of CO2 ice deposited.