How the CO2 concentration is determined in BPRP compset? (Emission-driven)

[sowon@postech_ac_kr]

Dear all,

I'm curious about the calculation flow of CO2 concentration in BPRP compset (coupled with BGC).

If the emissions are prescribed,
In my imagination, CO2 emission -> rough diagnostic ATM CO2-> radiation -> LND, OCN CO2 flux -> ATM CO2 ->??
or simultaneously calculated?

Is this process iterative for considering the feedback between climate change and carbon cycle?
How this feedback processes is considered in CESM2?

I saw CCSM_BGC settings.
prog CO2-> land, drag CO2 -> land, land CO2 flux -> atm...
But I don't know about the exact meaning of this and calculation flow...

If you just let me know the relevant literatures, It will be very helpful.

Happy New Year!

 

[klindsay]

Loosely speaking, the land model and the ocean model compute surface fluxes of CO2. These computations use an atmospheric CO2 concentration that is referred to as BGC CO2, since it is what BGC computations use for CO2 computations. The atmospheric CO2 concentration used in atmospheric radiative computations is referred to as RAD CO2.

The atmospheric model takes the surface fluxes from the land and ocean models, along with fossil fuel emissions, and computes a prognostic CO2 tracer, using those surface fluxes as a lower boundary condition. These fluxes are updated every coupling interval, which is 1 hour for the ocean model and 30 minutes for the land model in typical climate configurations. This tracer in the atmosphere is referred to as PROG CO2. The atmospheric model can also generate prescribed CO2 concentrations, such as fixed values, values read from a file, or values ramped with a 1% annual increase. Such values are referred to as DIAG CO2, because they are diagnostic/prescribed.

In the abbreviations BDRD and BPRP, B stands for BGC CO2, R stands for RAD CO2, D stands for DIAG CO2, and P stands for PROG CO2.

BDRD indicates that BGC CO2 and RAD CO2 computations use DIAG, i.e., prescribed, CO2. The atmosphere model still has a CO2 tracer that uses the land and ocean CO2 surface fluxes, but the values of this tracer are not used in any CO2 related computation.

BPRP indicates that BGC CO2 and RAD CO2 computations use PROG, i.e., prognostic CO2. The CO2 tracer computed by the atmospheric model is passed back to the land and ocean models for use in their BGC computations, and it is also used in atmospheric radiative computations.

Some information about BPRP vs BDRD is available in this year's CESM tutorial pages.

Hope this helps,
Keith

 

[sowon@postech_ac_kr]

Loosely speaking, the land model and the ocean model compute surface fluxes of CO2. These computations use an atmospheric CO2 concentration that is referred to as BGC CO2, since it is what BGC computations use for CO2 computations. The atmospheric CO2 concentration used in atmospheric radiative computations is referred to as RAD CO2.

The atmospheric model takes the surface fluxes from the land and ocean models, along with fossil fuel emissions, and computes a prognostic CO2 tracer, using those surface fluxes as a lower boundary condition. These fluxes are updated every coupling interval, which is 1 hour for the ocean model and 30 minutes for the land model in typical climate configurations. This tracer in the atmosphere is referred to as PROG CO2. The atmospheric model can also generate prescribed CO2 concentrations, such as fixed values, values read from a file, or values ramped with a 1% annual increase. Such values are referred to as DIAG CO2, because they are diagnostic/prescribed.

In the abbreviations BDRD and BPRP, B stands for BGC CO2, R stands for RAD CO2, D stands for DIAG CO2, and P stands for PROG CO2.

BDRD indicates that BGC CO2 and RAD CO2 computations use DIAG, i.e., prescribed, CO2. The atmosphere model still has a CO2 tracer that uses the land and ocean CO2 surface fluxes, but the values of this tracer are not used in any CO2 related computation.

BPRP indicates that BGC CO2 and RAD CO2 computations use PROG, i.e., prognostic CO2. The CO2 tracer computed by the atmospheric model is passed back to the land and ocean models for use in their BGC computations, and it is also used in atmospheric radiative computations.

Some information about BPRP vs BDRD is available in this year's CESM tutorial pages.

Hope this helps,
Keith

I am truly grateful for your kind explanation. I will look into the information you provided further.

Thank you again.