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PETM CONFIGURATION AND CHANGES FROM v.4.05.07.09
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The the PETM version of cbs-goldstein is based on cbs-goldstein version v.4.05.07.09 (see readme.cbs-goldstein.v4).
However, the updated radiative forcing code able to deal with CH4 has been added (surflux.F).
Also, changes have been made to load in PETm-specific topography and island files (gseto.F).
Also, the wind stress forcing has been changed and code added (gseta.F) to deal with the simplified zonal average nature of this.
All code changes are from an older PETM version of the model as created by Andrew Yool and Bob Marsh.
Code changes have also been made so that the goin file conforms to the current cbs-goldstein version
(which has one parameter less than the original PETM configuration).

Also, changed the CO2 percent rise parameter in the goin with a scaling factor for CH4
=> now both CO2 and CH4 can be set independently of atchem (which currently does not pass CH4 values anyway)
Scaling for each is relative to 278 ppm CO2 and 700 ppb CH4, respectively
This required minor changes and additions to gseta.F and surflux.F

Lastly, changes the longitudinal offset (par_grids_lon_offset) from 260E (-260) to 180E (-180) in
atchem_lib.f90, biogem_lib.f90, and sedgem_lib.f90

SUMMARY: source code files altered from standard v.4.05.07.09 are;
gseto.F
gseta.F
surflux.F
biogem_lib.f90
atchem_lib.f90, biogem_lib.f90, and sedgem_lib.f90

goin parameter values are not directly from Hargreaves et al. [2004] (the modern climate tuning)
but with the prescribed net atmospheric freshwater transports (necessary to get a good modern termohaline circulatioon going)
set to zero.

Topography and island path definition files are the 'workar' set (as per previously incarnations of the PETM model).
Wind stress forcing files are taux_u_b2002.interp and tauy_v_b2002.interp which are from Bice and Marotzke [2002]
and re-gridded by Andrew Yool. (These are very slightly different from those used previously.)


NOTES
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Because the wind-stress field is very different, case will have to be taken in scaling the air-sea gas transfer exchange rate.
(See the user-manual for info on this.)
Basically, the value of the 'Wanninkhof [1992] gas transfer parameterization coefficient 'a'' in biogem_config.par
will need to be adjusted. The mean global air-sea CO2 gas transfer coefficient ('Global mean K(CO2)') is given in
the results file *_misc_DATA_GLOBAL.res. It should be soemthing like 0.061 mol m-2 yr-1 uatm-1 and it is just a matter of
scaling the value in biogem_config.par to achieve (close to) this.

goin files from previous PETM configurations will not work.

Re-start files generated under previous PETM configurations will not work.