Changes between Version 49 and Version 50 of DevelopmentActivities/MergeOCN/Vuichard
- Timestamp:
- 2014-02-14T10:30:49+01:00 (10 years ago)
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DevelopmentActivities/MergeOCN/Vuichard
v49 v50 26 26 27 27 > B. Guenet [[BR]] 28 Soenke probably just added nitrogen on the CENTURY version that was already present in ORCHIDEE and did not totally updated CENTURY. I did not see reason to not update.28 > Soenke probably just added nitrogen on the CENTURY version that was already present in ORCHIDEE and did not totally updated CENTURY. I did not see reason to not update. 29 29 30 30 == N flows in soil - Routine : nitrogen_dynamics == … … 40 40 41 41 > B. Guenet [[BR]] 42 It is not clear why Soenke used the Montheit and Unsworht 1990 equation to calculate diffusion coefficient but it perhaps because he defined afpsmax as a function of soil texture which is not coherent with what is done in Sechiba. Indeed, sechiba defined the porosity as a parameter (the field capacity that could be considered as a synonym for porosity). I suggest to use another equation to define oxygen diffusion coefficient based on Wania et al., 2010 in GMD. They define equations based on regression thattakes into account the effect of soil water content on diffusion.42 > It is not clear why Soenke used the Montheit and Unsworht 1990 equation to calculate diffusion coefficient but it perhaps because he defined afpsmax as a function of soil > texture which is not coherent with what is done in Sechiba. Indeed, sechiba defined the porosity as a parameter (the field capacity that could be considered as a synonym for porosity). I suggest to use another equation to define oxygen diffusion coefficient based on Wania et al., 2010 in GMD. They define equations based on regression that takes into account the effect of soil water content on diffusion. 43 43 44 44 2. '''Calculation of the oxygen partial pressure'''. For both the calculation of the gradient of oxygen partial pressure (d(pO2)/dz) and the change in oxygen partial pressure (d(pO2)/dt), we need dz, the depth over which one makes the calculation. It is not clear to me which depth one should use. For information, OCN used z_decomp (see [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L705 here]) 45 45 46 46 > Exemple: I look at this point (Bertrand) 47 I think that Soenke assume that microbial activity only occurs between 0 and z_decomp. Therefore he used z_decomp to calculate d(pO2)/dz and d(pO2)/dt since it is assumed that no microbial activity occur below z_decomp.47 > I think that Soenke assume that microbial activity only occurs between 0 and z_decomp. Therefore he used z_decomp to calculate d(pO2)/dz and d(pO2)/dt since it is assumed that no microbial activity occur below z_decomp. 48 48 49 49 3. '''Calculation of the oxygen partial pressure''' (2). Still in the calculation of the change in oxygen partial pressure (d(pO2)/dt) in OCN, it seems that "dz" term (z_decomp) is missing in the following equation (see [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L705 here]) when we compare with the reference formulation (Li et al., 2000, Eq. 4 of Table 2) … … 51 51 > B. Guenet [[BR]] 52 52 53 I agree, this point must be clarified with Soenke53 > I agree, this point must be clarified with Soenke 54 54 55 55 4. '''Conversion Respiration to O2 pressure'''. The conversion factor [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L699 here] used for converting the respiration term in O2 pressure accounts for the air-filled porosity (see Li et al., 2000 eq. 3 table 2). In OCN, afps_max is used instead of afps. We keep the original formulation … … 80 80 81 81 > B. Guenet [[BR]] 82 Theoretically yes82 > Theoretically yes 83 83 84 84 11. '''Relative growth rate of Nox denitrifiers'''. One uses a parameter defined as the Half Saturation of N oxydes (kgN/m3) from Table 4 of Li et al., 2000. It is set to 0.083 in Li et al. and OCN uses the value 0.087. We keep the original value. It is also not clear if the unit of this parameter are kgN per m3 of soil or per m3 of solution. In OCN, when converting from (kgN m-3) to (gN m-2) we multiply by "dpu_cste*mx_eau_eau" (see [source:branches/orchidee-N/ORCHIDEE/src_stomate/stomate_soilcarbon.f90@19#L832 here]. I don't know if this is correct. If it is per m3 of solution one should at least consider that soil is not necessary at the field capacity (ie. dpu_cste*mx_eau_eau*soilhum). … … 175 175 176 176 > B. Guenet [[BR]] 177 I think it is ok like this because it considers only N leaching which of course depend on soil water content but in this case it is a flux of N.177 > I think it is ok like this because it considers only N leaching which of course depend on soil water content but in this case it is a flux of N. 178 178 179 179 27. '''Additional general comments'''. From my reading of the code of OCN, it appears that there are at least 3 processes/calculations for which we really need to be careful:
