light units for ec_Fobar

Discussion about coupled ecosystem models

Moderators: arango, robertson

Post Reply
Message
Author
jklinck
Posts: 31
Joined: Mon Jun 30, 2003 2:29 pm
Location: CCPO/ODU, USA

light units for ec_Fobar

#1 Post by jklinck » Fri Feb 13, 2015 7:16 pm

What are the units for the light values (ec_Fobar) in mod_eclight?

I am trying to compare this model to the one in Gregg and Carder (1990) where Ho in that paper has units of W/m2/nanometer.

These value differ by about 10. Are these values in micromole photons/m2/s? Converting these units don't give corresponding values.

Thanks,

John

User avatar
arango
Site Admin
Posts: 1082
Joined: Wed Feb 26, 2003 4:41 pm
Location: IMCS, Rutgers University
Contact:

Re: light units for ec_Fobar

#2 Post by arango » Mon Feb 16, 2015 5:29 pm

I don't know what are the units. This is used in the downwelling spectral irradiance routine ana_specir.h. This was adapted from a routine provided by Paul Bissett for the EcoSim model. That routine says that it is based on Gregg and Carder (1990) model and few units were provided. It is used to compute SpecIr (quanta/m2/s):

Code: Select all

!
!  Convert from W/cm/um to micromole quanta/m2/s.
!
              SpecIr(i,j,iband)=Ed(iband)*10.0_r8*qlam(iband)
So it is possible that there is a bug about the units in this routine. However, notice that the above statement is multiplied by 10. We would need to check backwards this routine and figure out what are the units. The ec_Fobar is used to compute:

Code: Select all

!
!  Correct solar constant for Earth-Sun distance.
!
      cff=(1.0_r8+0.0167_r8*COS(2.0_r8*pi*(yday-3.0_r8)/365.0_r8))**2
      DO iband=1,NBands
        Fo(iband)=ec_Fobar(iband)*cff
      END DO

Post Reply