Changes between Version 57 and Version 58 of DevelopmentActivities/MergeOCN/Vuichard
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- 2014-02-17T23:16:44+01:00 (10 years ago)
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DevelopmentActivities/MergeOCN/Vuichard
v57 v58 70 70 71 71 > B. Guenet [[BR]] 72 > I did not understood this part. 72 73 73 74 8. '''Nitrification rate'''. The equation for the nitrification rate comes from Schmid et al., 2001, Nutr. Cycl. Agro (eq.1) but the environmental factors used are from Zhang (2002) who used an other equation, especially for Temperature effect on nitrification. I don't know how this can be mixed together ? This seems particularly inappropriate because the default fraction of N-NH4 which is converted to N-NO3 appears equal to 2 day-1 (a factor "2" in the equation, see [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L805 here]). In Schmid et al., the nitrification rate at 20 ◦C and field capacity (knitrif,20) was set to 0.2 d−1 (10 times less...) … … 89 90 90 91 > B. Guenet [[BR]] 92 > From what I understood the parameter mx_eau_eau is the field capacity??? I think it is ok like it is. 91 93 92 94 12. '''Relative growth rate of Nox denitrifiers (2)'''. In OCN, the term mu_nox(max) is missing in the equation that defines the relative growth rate of total denitrifiers (see eq. 2 of Table 4 of Li et al., 2000). See [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L845 here]. In addition, in OCN, the Relative growth rate of Nox denitrifiers is ranged between 0.0005*som(:,iactive,m,icarbon) and 0.25 * som(:,iactive,m,icarbon)). No clear justification. This is not kept so far. 95 96 > B. Guenet [[BR]] 97 > I think that the term mu_nox(max) must be added in the equations. For the range of growth rate, it is probably a range fixed by Soenke to stabilize the code. It must be confirmed by Soenke 93 98 94 99 13. '''NO3 consumption by denitrification'''. This is based on Eq. 4 Table 4 of Li et al., 2000. In OCN ([source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L848 here]), multiplication by 0.1 of the NO3 consumption. There is no justification. This is not kept so far. 95 100 96 101 > B. Guenet [[BR]] 102 > I agree it was probably tunning... 97 103 98 104 14. '''denitrifier bacterial population change'''. This is based on Eq. 3 of Table 4 Li et al. (2000). In OCN, there is only the denitrifier bact population change that is defined, not the population itself. And the bacterial population change is used in place of the bacterial population in the calculation of the production of NO3, NOx, N2O by denitrification. [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L845 here]. I don't know how it may work. 99 105 100 106 > B. Guenet [[BR]] 107 > It implicitely assumes that the timestep of th model is sufficiently high to cover a total regeneration of the bacterial population. This is a strong assumption since the stomate_soilcarbon time step if 30min which is quite short to renew an entire bacterial population in soil. Must be corrected. 101 108 102 109 15. '''Vmax of nitrogen uptake by plants'''. In OCN, the same values are used both for uptake of NH4+ and NO3-. See p. 3 of the SM of Zaehle & Friend, 2010: "''As a first approximation average values for vmax, kNmin and KNmin are assumed for all PFTs (Table S1), and for both ammonium and nitrate''". However based on the two papers of Kronzucker et al. (1995, 1996), it seems that vmax should be much higher for NH4+ than for NO3- . We still use the same here for both NH4+ and NO3- as in OCN.
