Introduction
A new NCC paper provided a technology to rectify the fully-coupled model systematic bias.
The procedures are following:
- A free run (
FREE) after spin-up, of course, full of systematic biases. - A SST restoring run (
SSTR) toward observational SST.- The tech support to restore SST may refer to my previous notes (in Chinese)
- Relevant scripts for preprocessing.
- Get downward heat flux differences (SW+LW+LH+SH) from
SSTR-FREE, make it as a constant forcing and add the forcing to free run, namelyHEATR_CTRL. - Following 3, Do what you need (
HEATR_SEN).
Heat Flux Correction
I will then show the procedures to conduct the HEATR_CTRL run.
First we lock the definition part for the cam variables to hold data input to & output from the coupler. In $CESMROOT/models/atm/cam/src/control:
!
! Public data types
!
public cam_out_t ! Data from atmosphere
public cam_in_t ! Merged surface data
!---------------------------------------------------------------------------
! This is the data that is sent from the atmosphere to the surface models
!---------------------------------------------------------------------------
type cam_out_t
integer :: lchnk ! chunk index
integer :: ncol ! number of columns in chunk
real(r8) :: tbot(pcols) ! bot level temperature
real(r8) :: zbot(pcols) ! bot level height above surface
real(r8) :: ubot(pcols) ! bot level u wind
real(r8) :: vbot(pcols) ! bot level v wind
real(r8) :: qbot(pcols,pcnst) ! bot level specific humidity
real(r8) :: pbot(pcols) ! bot level pressure
real(r8) :: rho(pcols) ! bot level density
real(r8) :: netsw(pcols) !
real(r8) :: flwds(pcols) !
real(r8) :: precsc(pcols) !
real(r8) :: precsl(pcols) !
real(r8) :: precc(pcols) !
real(r8) :: precl(pcols) !
real(r8) :: soll(pcols) !
real(r8) :: sols(pcols) !
real(r8) :: solld(pcols) !
real(r8) :: solsd(pcols) !
real(r8) :: thbot(pcols) !
real(r8) :: co2prog(pcols) ! prognostic co2
real(r8) :: co2diag(pcols) ! diagnostic co2
real(r8) :: psl(pcols)
real(r8) :: bcphiwet(pcols) ! wet deposition of hydrophilic black carbon
real(r8) :: bcphidry(pcols) ! dry deposition of hydrophilic black carbon
real(r8) :: bcphodry(pcols) ! dry deposition of hydrophobic black carbon
real(r8) :: ocphiwet(pcols) ! wet deposition of hydrophilic organic carbon
real(r8) :: ocphidry(pcols) ! dry deposition of hydrophilic organic carbon
real(r8) :: ocphodry(pcols) ! dry deposition of hydrophobic organic carbon
real(r8) :: dstwet1(pcols) ! wet deposition of dust (bin1)
real(r8) :: dstdry1(pcols) ! dry deposition of dust (bin1)
real(r8) :: dstwet2(pcols) ! wet deposition of dust (bin2)
real(r8) :: dstdry2(pcols) ! dry deposition of dust (bin2)
real(r8) :: dstwet3(pcols) ! wet deposition of dust (bin3)
real(r8) :: dstdry3(pcols) ! dry deposition of dust (bin3)
real(r8) :: dstwet4(pcols) ! wet deposition of dust (bin4)
real(r8) :: dstdry4(pcols) ! dry deposition of dust (bin4)
end type cam_out_t
!---------------------------------------------------------------------------
! This is the merged state of sea-ice, land and ocean surface parameterizations
!---------------------------------------------------------------------------
type cam_in_t
integer :: lchnk ! chunk index
integer :: ncol ! number of active columns
real(r8) :: asdir(pcols) ! albedo: shortwave, direct
real(r8) :: asdif(pcols) ! albedo: shortwave, diffuse
real(r8) :: aldir(pcols) ! albedo: longwave, direct
real(r8) :: aldif(pcols) ! albedo: longwave, diffuse
real(r8) :: lwup(pcols) ! longwave up radiative flux
real(r8) :: lhf(pcols) ! latent heat flux
real(r8) :: shf(pcols) ! sensible heat flux
real(r8) :: wsx(pcols) ! surface u-stress (N)
real(r8) :: wsy(pcols) ! surface v-stress (N)
real(r8) :: tref(pcols) ! ref height surface air temp
real(r8) :: qref(pcols) ! ref height specific humidity
real(r8) :: u10(pcols) ! 10m wind speed
real(r8) :: ts(pcols) ! merged surface temp
real(r8) :: sst(pcols) ! sea surface temp
real(r8) :: snowhland(pcols) ! snow depth (liquid water equivalent) over land
real(r8) :: snowhice(pcols) ! snow depth over ice
real(r8) :: fco2_lnd(pcols) ! co2 flux from lnd
real(r8) :: fco2_ocn(pcols) ! co2 flux from ocn
real(r8) :: fdms(pcols) ! dms flux
real(r8) :: landfrac(pcols) ! land area fraction
real(r8) :: icefrac(pcols) ! sea-ice areal fraction
real(r8) :: ocnfrac(pcols) ! ocean areal fraction
real(r8), pointer, dimension(:) :: ram1 !aerodynamical resistance (s/m) (pcols)
real(r8), pointer, dimension(:) :: fv !friction velocity (m/s) (pcols)
real(r8), pointer, dimension(:) :: soilw !volumetric soil water (m3/m3)
real(r8) :: cflx(pcols,pcnst) ! constituent flux (evap)
real(r8) :: ustar(pcols) ! atm/ocn saved version of ustar
real(r8) :: re(pcols) ! atm/ocn saved version of re
real(r8) :: ssq(pcols) ! atm/ocn saved version of ssq
real(r8), pointer, dimension(:,:) :: depvel ! deposition velocities
end type cam_in_t
Here we note that SW and LW are from coupler, and LH and SH are from coupler. Then we will grep the relationship between these things and the variables in the output file of CAM model.
| Name in code | Name in output |
|---|---|
| cam_out%netsw | FSNS |
| cam_out%flwds | FLDS |
| cam_in%lhf | LHFLX |
| cam_in%shf | SHFLX |
Next, in physpkg.F90 (still this guy!), we found that lhf is calculated by cam_in%cflx (moisture flux from the surface). As the moisture flux is a constituent flux, I decide to remain the latent heat at first.
Therefore, the question is to add a constant forcing to netsw, flwds, and shflx.
Luckily, we have tried to change the shflx in previous trial.
For netsw and flwds, physpkg.F90 call the radiation, and in radiation_tend module, the netsw is set. Note that in radiation.F90:
real(r8), parameter :: cgs2mks = 1.e-3_r8
flds(i) = cam_out%flwds(i)*cgs2mks
cam_out%flwds(i) = cam_out%flwds(i)*cgs2mks
I don’t know why they organize the data structure like this. But netsw and flwds both can be handled similarly after physpkg call the radiation module.
The modified code files have been uploaded to github.
Updated 2018-11-01