| 
  private | 
| [in] | t2m | air temperature | 
| [in] | dt | time step (s) | 
| [in] | julian | julian day of year (fractional) ( 0 <= julian < yearlen ) | 
| [in,out] | gdd | growing degress days | 
| [out] | ipa | planting index index(0=off, 1=on) | 
| [out] | iha | havestindex(0=on,1=off) | 
| [out] | pgs | plant growth stage(1=s1,2=s2,3=s3) | 
Referenced by carbon_crop().