which solar forcing file to use

[bates]

Hi,We are conducting experiments in which we use an 1850 compset but want to let the solar forcing vary as it would in a 20th Century transient run. We are initializing with restarts from an 1850 WACCM run at various states of ENSO. We then run the model 5 years and modify the solar forcing file so that the model immediately sees an increase in solar forcing. We want to make sure that we're using the correct solar forcing file. I did a quick test case set up using a 20C compset and the cesm1_0_6 tag (which is what we'll use) and see that the solar forcing file is thisspectral_irradiance_Lean_1610-2009_ann_c100405.nc.However, we looked at some other WACCM runs, b40.1955-2005.2deg.wcm.00x, and see that a daily solar file was used. These are older CCSM4 runs, I assume. Should we use the default that contains annual means for these experiments? Basically we want to use whatever is the standard for WACCM.
Thanks,
Susan

 

[mmills]

Hi Susan,For CMIP5, we had daily varying solar irradiance available from 1950 to present day. We used the annually varying solar to run from 1850 to 1955. Our delivered transient historical CMIP5 runs were those from 1955-2005, which used the daily varying solar. These runs are b40.1955-2005.2deg.wcm.00[234]. We have since added runs 5, 6, and 7. These all used this file: spectral_irradiance_Lean_1950-2140_daily_c100804.ncWe also used this file for our RCP runs. As explained in the metadata of that file, irradiances for 2009-2140 were created by repeating the last 4 cycles (cycle 20-23) with values from 1965 to 2008 inclusive mapping to 2009-2052, 2053-2096, 2097-2140. 

 

[bates]

Thanks Mike. One more question, I was just looking at the namelists again and saw spe_data_file and solar_parms_file. If we shift the data in time in the solar_data_file, should we also shift these other two to match? Are there other files I should shift in relation to solar forcing?Susan

 

[mmills]

Yes, the time on the spe_data_file and solar_parms_file should match the solar_data_file. They all vary with the 11-year solar cycle. Those are the only solar input files we use.

 

[bates]

Great! Thanks Mike!

 

[bates]

Sorry, one more question. The spe_data_file does not show up in an out of the box run using B_1850-2000_WACCM_CN. Do I need to add this to the namelist, or is it not needed for this compset?Thanks,
 Susan

 

[bates]

By the way, we're using cesm1_0_6. I don't know if that plays into in of this or not. Also, the control simulation that we're using did not have an spe_data_file set, so I'm thinking we don't need it. If we're going to compare the experiment to the control, we want to follow what the control did....unless you tell me I need the file to modify all aspects of solar forcing and somehow that was included in the control.

 

[mmills]

SPE = solar proton events, high-energy particles from solar flares. We have data starting in 1963. The effect of these are to produce odd nitrogen in the upper atmosphere that descends to the stratosphere, affecting the ozone layer chemistry. So it is a part of solar variability. Whether you need to include it depends on the goals of your study.

 

[bates]

Got it! Thanks again!