the abnomal result

[yangqian12345@sina_com]

hello everyone:
I do a aerosol experience,the variable ts(surface temperature(radiactive)) difference between with sulfate aerosol modeling and without sulfate aerosol modeling is range from -15 to 12K,I thought this is bigger than normal.but I don't know why. If someone can give me some suggestion,I will very appreciate!

 

[rneale]

The answer to this quesiton depends on the following
1. How long an integration are you running? (systematic differences between two experients could be that large if the run last only a couple of years)
2. Are the values of TS difference over a small region/over land/global etc?
3. When you say with and withough suplaht aerosol modelling do you mean with diagnostic sulphate aerosols turned on/of or with prognostic aerosols?
Please give as much info. as possible
Thanks

 

[yangqian12345@sina_com]

Dear rneale:
Thanks for your help very much!
I do the modeling about 40 years(from 1960 to 2000).I compared the TS difference in 1970'S,The Ts difference is bigger in some regions not over the global,mainly over the land.I found other years also have same situation.
The sulfate aerosol modeling which I used is turned on(off) prescribed_sulfur. Besides Ts,the variable T(26 levels)difference with this two experimence(with and without sulfate modeling) is also bigger.I do this two experimence as follows:
(1)with sulfate modeling
sulscl = 1.0 ,sulscl_rf=0;dustscl= 0,dustscl_rf=0;carscl=0,carscl_rf=0;ssltscl=0,sslt scl_rf=0.
(2)without sulfate modeling
sulscl = 0 ,sulscl_rf=0;dustscl= 0,dustscl_rf=0;carscl=0,carscl_rf=0;ssltscl=0,sslt scl_rf=0.
Please give me some suggestion,Thanks again.

 

[rneale]

If you turn off all the diagnostic aeorsols you will definately have a large impact on the direct aerosol affect giving you a postive top of atmosphere (TOA) positive energy bias. If you check the global difference between TOA short wave flux (FSNT) and long wave flux (FLNT) then this will give you an idea of how the energy balance has changed, if this more than a few watts then there is a problem. If you are running with all aerosols on then the TOA energy balance should about zero. Locally there will be large changes e.g. sulphate aerosols give a global radiative forcing of about -0.8W/m^2 but locally it will be much higher as the sulphat sources are locally much higher (over East asia).

Just to mention that the _rf namelist variables refer to the parallel radiative forcing calculation only, and they only have an effect when RADFORCE = .TRUE. Refer to the CAM documentation for this.

 

[yangqian12345@sina_com]

Dear rneale:
Thanks for your zealous help!
To you suggestion, I knew more about why cause this problem, but I can not know how to solve the problem,what you said"if you are running with all aerosols on then the TOA energy balance should about zero", I don't clearly know your mean about running with all aerosols on? For my understanding if turn on the other aeorsols use parameters such as AERO_CARBON, AERO_FEEDBACK_CARBON, AERO_SEA_SALT and so on. and the other way is turn on the aerosols by set parameters dustscl= 1, carscl=1, ssltscl=1 in my two experimence.
If I want to do two experimence of with sulfate modeling and without sulfate modeling, what should I set parameter in the namelist? Which set of parameter is correct? Please give me a hint, Thanks again.

 

[bundy]

It is important to distinguish between the prescribed and prognostic aerosols.

Prescribed aerosol masses are read from a monthly-average climatology, and I believe these are what Rich is referring to when he says 'with all of the aerosols on'.

Prognostic, or predicted aerosols, are calculated by the model based on emissions datasets and are advected, convected, reacted, etc. to predict the aerosol concentrations. The namelist variables
AERO_CARBON, AERO_FEEDBACK_CARBON, AERO_SEA_SALT
refer to the prognostic aerosols. The only prognostic aerosol package that actually works in the version you have is the sulfur.

The default is that prescribed, not prognostic, aerosols are used. So you should not be turning on aero_carbon,aero_seasalt, etc.

The radiative scaling factors (sulscl, carscl, ... sulscl_rf, carscl_rf,...) are applied to whatever aerosol mass is being used, not distinguishing between prognostic and prescribed.

The issue of the TOA balance is why I recommended (in an email earlier today) that you leave all scales = 1, except for the sulfate forcing experiment you want to do. Setting the other aerosol scales = 0 will throw the model further out of balance.