Changes between Version 72 and Version 73 of DevelopmentActivities/MergeOCN/Vuichard

Timestamp:

2014-03-17T09:43:34+01:00 (10 years ago)

Author:

bguenet

Comment:

--

DevelopmentActivities/MergeOCN/Vuichard

@@ -154 +154 @@
 
 22. '''N uptake by plants''' (2). In eq. 8 of SM of Zaehle et al. (2010) I think there is an error. It should not be (Nmin X KNmin) but (Nmin + KNmin). The source code of OCN is correct (see [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L897 here]).
+
+
+> B. Guenet [[BR]]
+> I agree it is based on Michaelis Menten equation.
 
 23. '''Loss of NH4 due to volatilisation of NH3'''. See Li et al. 1992, JGR, Table 4. It's used the current dissociation of [NH3] to [NH4+] (see Table 4 and Appendix A of Zhang et al. 2002):
@@ -179 +183 @@
  This means that the value stored in soil_n_min(:,:,iammonium) corresponds to the total N of both [NH4+] and [NH3]. This makes sense to my opinion, but I wonder if one should not account for this partitioning between [NH4+] and [NH3] in other processes. To check.
   d. The X value should relate to [NH3]/[NH4+] but to my opinion the X value used in the equation in OCN corresponds to [NH4+]/[NH3]. Is this a bug ?
+> B. Guenet [[BR]]
+> I do not understand it this way for me X is [NH3]/[NH4+] in OCN.
+
  In conclusion, I propose the formulation
 {{{
 frac_nh3(:) = 10.0**(pH(:)-pk_NH4) / (1. + 10.0**(pH(:)-pk_NH4)) 
 }}}
+
+> B. Guenet [[BR]]
+> I agree formulation in Li et al and in OCN are a bit strange. But when calculating frac_nh3 I obtained:
+
+{{{
+
+frac_nh3(:) = 10.0**(pk_NH4-pH(:)) / (1. + 10.0**(pk_NH4-pH(:))) 
+}}}
+
+> We must check that together
 
 24. '''Reduction of the ammonia volatilization'''. See [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L953 here]. This seems a patch added to OCN in order to (as mentioned in OCN) reduced emissions at low concentration (problem of only one soil layer). This is not activated yet but it is kept as a comment.
@@ -212 +229 @@
 d. The factor 2 [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L805 here] related to point 8.
 e. The factor 30 [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L809 here] related to point 9.
-f.