atmospheric energy balance in CAM4

[liurj04@gmail_com]

  I have run CAM4(CESM1.2.0) with prescribed climatological SST (10 years simulation). But I found the atmosperic energy balance (FSNT-FLNT) was not close to zero ,which is  about -26 W/m2.  I ploting the TOA net shortwave radiative flux (FSNTOA) and upwelling longwave flux at top of model (FLUT). The FSNTOA and FLUT have similar pattern as AMWG diags with CAM4: http://www.cesm.ucar.edu/experiments/cesm1.0/diagnostics/cam4_diag/f40.1979_amip.track1.2deg.001/f40.1979_amip.track1.2deg.001-obs_1980-2004/ I am confused to why the atmospheric energy banlance is not close to zero , Is there some wrong with my calculation of  FSNT-FLNT ? My ncl scripts of calculation are as follows: begin  fils = systemfunc("ls home/archive/cam4_bam/atm/hist/cam4_bam.cam.h0.*.nc")  f    = addfiles(fils, "r")  fsnt = addfiles_GetVar(f,fils,"FSNT")  flnt = addfiles_GetVar(f,fils,"FLNT")  fsnt_ave = dim_avg_n_Wrap(fsnt,0)           ; 10 years mean  flnt_ave = dim_avg_n_Wrap(flnt,0)   diff = fsnt_ave  diff = fsnt_ave-flnt_ave  radi_avg = avg(diff)  print(radi_avg)end The output is -26.63861 the attachment is plot of annual mean FSNTOA and FLUTAny suggestions will be appreciated ! 

 

[hannay]

From your script, it seems that you are not doing weighted averages. You are giving the same weigh to every latitude. You need to specify the weigh of each latiude when you are doing your averaging. 

 

[hannay]

From your script, it seems that you are not doing weighted averages. You are giving the same weigh to every latitude. You need to specify the weigh of each latiude when you are doing your averaging. 

 

[rneale]

I stongly suspect it is because you're not applying the latitude weighting (gw) for the averageing step. Try ncl routines for performing this weighted average https://www.ncl.ucar.edu/Document/Functions/Built-in/dim_avg_wgt_n.shtml

 

[rneale]

I stongly suspect it is because you're not applying the latitude weighting (gw) for the averageing step. Try ncl routines for performing this weighted average https://www.ncl.ucar.edu/Document/Functions/Built-in/dim_avg_wgt_n.shtml

 

[liurj04@gmail_com]

Hi , hannay and nealeThanks a lot for your help. By applying the latitude weighting, the value of averaged FSNT-FLNT is about 2W/m2. This value seems ok.

 

[liurj04@gmail_com]

Hi , hannay and nealeThanks a lot for your help. By applying the latitude weighting, the value of averaged FSNT-FLNT is about 2W/m2. This value seems ok.