IPCC = OFF scenario

[sanjivconscious@gmail_com]

Hi All,

I am Sanjiv, PhD student at Purdue University. Wish you all a very happy and prosperous new year.

My orginal question was:

When we set IPCC_MODE = OFF in env_conf, then which forcing is being
considered. More simply: What is CO2 concentration in the atmosphere, it is
present day CO2 concentration (350 or 365 ppm) or anything else.

I have a repy from Gary Strand that

It's not present day, as you're trying to run an 1870 control, therefore, the CO2 value will be set to the 1870 contained in ghg_1870_2100_c040122.nc, which is ~289.3 ppm.

So my new question is:

If we say for IPCC = OFF, CO2 concentration is set to 289.3 ppm (1870 value). What happens to SST and sea ice data file. Does is also get set to 1870 value or not. Because i am running CAM and CLM in active mode and SST and sea ice, i am taking as data component only.

Any clarification in this regard is highly appreciated

thanks
sanjiv

 

[sanjivconscious@gmail_com]

Hi All,

My assessemnt is when we set IPCC_MODE = OFF, model runs for present day scenario (CO2 concentration - 355 ppm) and presnt day SST (1949-2001) climatology. Please note that I am running CAM and CLM in active mode and Ocean and Ice as data component only.

There are two argument behind this assessemnt:

1) deafult value of CO2VMR = 355 ppm in [User’s Guide to the NCAR
Community Atmosphere Model (CAM 3.0), page 66].

2) file "ghg_1870_2100_c040122.nc" contains CO2 concentration from 1870 to 2100. But when we run the model for IPCC=OFF this file is not get copied to "cam" executable direcoty.

So that imples that model should use default value of CO2VMR

Similarly, for SST in IPCC=OFF secnario model uses "Hurrell SST Climatlogy"
which is 1949-2001 mean, see the link below

http://cires.colorado.edu/science/groups/chase/projects/climateland/global/

which says....

"clim: Standard CCSM 3.0 monthly climatology sea surface temperatures and sea ice distributions taken from the period 1949 - 2001 and widely refered to as the Hurrell SST climatology."

So, in summary IPCC=OFF runs the model for present day scenario.

Am i right in my assessment?

Thanks
Sanjiv