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Dramatic cooling with B_1850 simulation

W

whannah

Member
I'm trying to run 1x and 4x CO2 experiments with CESM 1.1.1 at 0.9x1.25_gx1v6 resolution, but they both have a dramatic cooling in the first ~10-20 years. I've attached a timeseries of the global mean surface temperature with 1xCO2 in blue and 4xCO2 in red. I've also attached some net radiative flux variables. You'll notice the TOA net solar flux is different, but this seems to mostly be due to an increase in sea ice in the 1x CO2 simulation. The downwelling solar flux is identical in both runs.I'm guessing that my custom compset might be causing the problem, but I have no idea how. My custom compset file looks like this:I've also been thinking that this could just be because my initial conditions are from a different model configuration that runs warmer. However, when I look at the January sea-ice fraction, the sea-ice extends down to ~45N in the Pacific, which is pretty unrealistic.I also heard that it might be better to start as a hybrid using one of the "b40" runs as the intial condition, found here:https://svn-ccsm-inputdata.cgd.ucar.edu/trunk/inputdata/ccsm4_init/Someone also suggested it could be related to the use of 30 levels instead of 26?Any other ideas to explain this would be a huge help.

Thanks,
Walter
 
W

whannah

Member
Still doing some detective work here, but it seems that my problem might be realted to the solar constant being too low!

The compset I was using used 1360 W/m2. It seems other compsets default to somethign like 1365 or 1366 is a more realistic number. I'm going to rerun with that and see if it helps. 
 
W

whannah

Member
Still doing some detective work here, but it seems that my problem might be realted to the solar constant being too low!

The compset I was using used 1360 W/m2. It seems other compsets default to somethign like 1365 or 1366 is a more realistic number. I'm going to rerun with that and see if it helps. 
 
W

whannah

Member
Still doing some detective work here, but it seems that my problem might be realted to the solar constant being too low!

The compset I was using used 1360 W/m2. It seems other compsets default to somethign like 1365 or 1366 is a more realistic number. I'm going to rerun with that and see if it helps. 
 
W

whannah

Member
Still having issues here. I tried increasing the solar constant, but I'm still getting some intense cooling at the beginning of my simulation. I also rechecked the global mean surface pressure, and it seems that I might be losing mass (see attached image).How do I debug this?


 
W

whannah

Member
Still having issues here. I tried increasing the solar constant, but I'm still getting some intense cooling at the beginning of my simulation. I also rechecked the global mean surface pressure, and it seems that I might be losing mass (see attached image).How do I debug this?


 
W

whannah

Member
Still having issues here. I tried increasing the solar constant, but I'm still getting some intense cooling at the beginning of my simulation. I also rechecked the global mean surface pressure, and it seems that I might be losing mass (see attached image).How do I debug this?


 
W

whannah

Member
So the CAM model in my simuation is definitely losing mass!Looking deeper into the CAM log file I was able to vaerfy this is happening to the total mass, but not the dry mass:./atm.log.150717-144226: Total Mass=   985.295864156963      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.278204112098      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.260864316040      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.243214502113      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.230542676859      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.221509335472      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.213235967701      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.202897953747      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.193714916467      (mb), Dry Mass=   982.880000000000      (mb...
./atm.log.150719-003830: Total Mass=   984.653719637187      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.649685267953      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.646827016269      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.646623676145      (mb), Dry Mass=   982.880000000676      (mb
./atm.log.150719-003830: Total Mass=   984.645805548654      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.641969249719      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.640331033626      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.641266990479      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.640535370222      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.636077877333      (mb), Dry Mass=   982.880000000679      (mb I also noticed a lot of "QNEG" warnings. So maybe water is being fluxed into the ocean? Or maybe just rained out?

Is it bad to use the 0.9x1.25 resolution in CAM while using gx1v6 resolution in the ocean?
 
W

whannah

Member
So the CAM model in my simuation is definitely losing mass!Looking deeper into the CAM log file I was able to vaerfy this is happening to the total mass, but not the dry mass:./atm.log.150717-144226: Total Mass=   985.295864156963      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.278204112098      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.260864316040      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.243214502113      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.230542676859      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.221509335472      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.213235967701      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.202897953747      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.193714916467      (mb), Dry Mass=   982.880000000000      (mb...
./atm.log.150719-003830: Total Mass=   984.653719637187      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.649685267953      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.646827016269      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.646623676145      (mb), Dry Mass=   982.880000000676      (mb
./atm.log.150719-003830: Total Mass=   984.645805548654      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.641969249719      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.640331033626      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.641266990479      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.640535370222      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.636077877333      (mb), Dry Mass=   982.880000000679      (mb I also noticed a lot of "QNEG" warnings. So maybe water is being fluxed into the ocean? Or maybe just rained out?

Is it bad to use the 0.9x1.25 resolution in CAM while using gx1v6 resolution in the ocean?
 
W

whannah

Member
So the CAM model in my simuation is definitely losing mass!Looking deeper into the CAM log file I was able to vaerfy this is happening to the total mass, but not the dry mass:./atm.log.150717-144226: Total Mass=   985.295864156963      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.278204112098      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.260864316040      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.243214502113      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.230542676859      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.221509335472      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.213235967701      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.202897953747      (mb), Dry Mass=   982.880000000000      (mb
./atm.log.150717-144226: Total Mass=   985.193714916467      (mb), Dry Mass=   982.880000000000      (mb...
./atm.log.150719-003830: Total Mass=   984.653719637187      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.649685267953      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.646827016269      (mb), Dry Mass=   982.880000000675      (mb
./atm.log.150719-003830: Total Mass=   984.646623676145      (mb), Dry Mass=   982.880000000676      (mb
./atm.log.150719-003830: Total Mass=   984.645805548654      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.641969249719      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.640331033626      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.641266990479      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.640535370222      (mb), Dry Mass=   982.880000000679      (mb
./atm.log.150719-003830: Total Mass=   984.636077877333      (mb), Dry Mass=   982.880000000679      (mb I also noticed a lot of "QNEG" warnings. So maybe water is being fluxed into the ocean? Or maybe just rained out?

Is it bad to use the 0.9x1.25 resolution in CAM while using gx1v6 resolution in the ocean?
 
hannay

hannay

Cecile Hannay
AMWG Liaison
Staff member
You are using CAM4 with 30 levels. It is an unsupporetd configuration and when you use CAM4 with 30-level, you will get too much low-level cloud and large biases in the shortwave cloud forcing.See pg 2875 from http://journals.ametsoc.org/doi/pdf/10.1175/2008JCLI2479.1
 
hannay

hannay

Cecile Hannay
AMWG Liaison
Staff member
You are using CAM4 with 30 levels. It is an unsupporetd configuration and when you use CAM4 with 30-level, you will get too much low-level cloud and large biases in the shortwave cloud forcing.See pg 2875 from http://journals.ametsoc.org/doi/pdf/10.1175/2008JCLI2479.1
 
hannay

hannay

Cecile Hannay
AMWG Liaison
Staff member
You are using CAM4 with 30 levels. It is an unsupporetd configuration and when you use CAM4 with 30-level, you will get too much low-level cloud and large biases in the shortwave cloud forcing.See pg 2875 from http://journals.ametsoc.org/doi/pdf/10.1175/2008JCLI2479.1
 
W

whannah

Member
Thanks Cecile, it looks like that was the problem. I had no idea adding a few more levels would ruin the whole simulation! I didn't notice the shortwave cloud forcing problem though. The cooling problem seemed to be more directly related to the dramatic drop in water vapor from intense tropical rainout, which had the expected effect of reducing the greenhouse effect.I reran my experiment with 26 levels, and the climate was stable. So I guess that's what I'm stuck with.

Thanks again!
 
W

whannah

Member
Thanks Cecile, it looks like that was the problem. I had no idea adding a few more levels would ruin the whole simulation! I didn't notice the shortwave cloud forcing problem though. The cooling problem seemed to be more directly related to the dramatic drop in water vapor from intense tropical rainout, which had the expected effect of reducing the greenhouse effect.I reran my experiment with 26 levels, and the climate was stable. So I guess that's what I'm stuck with.

Thanks again!
 
W

whannah

Member
Thanks Cecile, it looks like that was the problem. I had no idea adding a few more levels would ruin the whole simulation! I didn't notice the shortwave cloud forcing problem though. The cooling problem seemed to be more directly related to the dramatic drop in water vapor from intense tropical rainout, which had the expected effect of reducing the greenhouse effect.I reran my experiment with 26 levels, and the climate was stable. So I guess that's what I'm stuck with.

Thanks again!
 
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