# How to set up the radiation scheme for Palaeo-simulations? – in #9: CCLM

#### in #9: CCLM

There are two ways, a quick and a flexible one. For both first determine the equivalent CO2 concentration in ppm and convert it into mixing ratio by dividing by 658157.16

The quick one:

```CASE (10)
! RCP85 scenario (for 1950 <= zyear <= 2150)
!   eff. CO2 (all GreeHouseGases (GHG) considered)
zqco2 = ( – 4.0501145412E+07_ireals               &
+ 7.9386473439E+04_ireals * zyear       &
– 5.8292720579E+01_ireals * zyear*zyear &
+ 1.9002921793E-02_ireals * zyear**3    &
– 2.3202412328E-06_ireals * zyear**4) * 1.519E-06_ireals```

END SELECT zqco2 = …. ! insert your mixing ratio here

The flexible one:
in organize_physics.f90 change

```  IF (ico2_rad.GT.10 )  ico2_rad  = ico2_rad_d
```
to
```  IF (ico2_rad.GT.11 )  ico2_rad  = ico2_rad_d
```

```  zyearmin = 1950
```
to
```IF (ico2_rad < 11) THEN
zyearmin = 1950
ELSE
zyearmin =    ! .... put a year lower than the start year of your simulation period here
```
and change
```CASE (10)
! RCP85 scenario (for 1950 <= zyear <= 2150)
!   eff. CO2 (all GreeHouseGases (GHG) considered)
zqco2 = ( – 4.0501145412E+07_ireals               &
+ 7.9386473439E+04_ireals * zyear       &
– 5.8292720579E+01_ireals * zyear*zyear &
+ 1.9002921793E-02_ireals * zyear**3    &
– 2.3202412328E-06_ireals * zyear**4) * 1.519E-06_ireals```

END SELECT to
```CASE (10)
! RCP85 scenario (for 1950 <= zyear <= 2150)
!   eff. CO2 (all GreeHouseGases (GHG) considered)
zqco2 = ( – 4.0501145412E+07_ireals               &
+ 7.9386473439E+04_ireals * zyear       &
– 5.8292720579E+01_ireals * zyear*zyear &
+ 1.9002921793E-02_ireals * zyear**3    &
– 2.3202412328E-06_ireals * zyear**4) * 1.519E-06_ireals

CASE (11)
!… last millenium
zqco2  =     !… insert your mixing ratio here

ENDSELECT```
In the CCLM namelist PHYCTL set
```ico2_rad=11
```
In the same way you can define several different mixing ratios with additional numbers 12, 13, 14 etc.