Dear Alison, Chris,
I have a few questions about items 21, 22, 23:
21: raStem surface_upward_mass_flux_of_carbon_due_to_plant_respiration_in_stems:
22: raLeaf surface_upward_mass_flux_of_carbon_due_to_plant_respiration_in_leaves
23: raRoot surface_upward_mass_flux_of_carbon_due_to_plant_respiration_in_roots
Q1: Such terms, which relate to the CO2 flux into the atmosphere, are usually of the form "..flux_of_carbon_dioxide_expressed_as_carbon...".
Have you decided that the longer form is redundant here?
Q2: We also have an existing name "plant_respiration_carbon_flux" which is used for variable "ra", as in CMIP5. "plant_respiration_carbon_flux" is described as a mass flux of carbon into the atmosphere and soil: would it be safe to assume that the carbon respiration flux into soil is the component from the roots? Shouldn't this be something like plant_respiration_carbon_flux_from_roots_into_soil?
Q3: there should be a name for "raOther" somewhere, which would follow the pattern established for "nppOther" in this discussion, but does "raOther" include fluxes into soil and atmosphere, as "ra", or is it just a flux into the atmosphere, as "raLeaf" and "raStem"?
regards,
Martin
________________________________
From: Juckes, Martin (STFC,RAL,RALSP)
Sent: 04 April 2018 20:37
To: Pamment, Alison (STFC,RAL,RALSP); 'Jones, Chris D'; cf-metadata at cgd.ucar.edu
Subject: Re: New standard names for C4MIP - part 2
Dear Alison, Chris,
I've added some comments on item 27 below (in blue if your client shows colour),
regards,
Martin
________________________________
From: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> on behalf of Alison Pamment - UKRI STFC <alison.pamment at stfc.ac.uk>
Sent: 04 April 2018 17:04
To: 'Jones, Chris D'; cf-metadata at cgd.ucar.edu
Subject: Re: [CF-metadata] New standard names for C4MIP - part 2
Dear Chris,
> Now agreed: 1, 2, 3, 4, 7, 11, 21.
Okay, thank you. These names are all now accepted and will be published in the next update of the standard name table.
Only five left to go...
15. (CMIP short name fNdep)
We've discussed various solutions for this one, but now we seem to have settled on using an existing name:
> So overall I favour going with the "tendency_of_atmosphere_mass_content_of_nitrogen_compounds_expressed_as_nitrogen_due_to_deposition" name
Thank you. I will remove this one from the list of proposals.
16. (CMIP short name fNfert)
Chris wrote:
> Thanks for the options - I think I favour not saying "organic and inorganic" in the name, and just going with " nitrogen_compounds_expressed_as_nitrogen". This seems simpler and the former doesn't add anything extra I don't think.
Okay thank you. So I think we are now agreed on the following:
tendency_of_soil_mass_content_of_nitrogen_compounds_expressed_as_nitrogen_due_to_fertilization (kg m-2 s-1)
' The phrase "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "soil content" of a quantity refers to the vertical integral from the surface down to the bottom of the soil model. For the content between specified levels in the soil, standard names including "content_of_soil_layer" are used. The phrase "expressed_as" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. "Nitrogen compounds" summarizes all chemical species containing nitrogen atoms. The list of individual species that are included in this quantity can vary between models. Where possible, the data variable should be accompanied by a complete description of the species represented, for example, by using a comment attribute. "Fertilization" means the addition of artifi
cial fertilizers and animal manure to soil for the purpose of increasing plant nutrient concentrations.'
This name is accepted for publication in the standard name table and will be added at the next update.
24. (CMIP6 short name nppOther)
Chris wrote:
> OK, if there are other variables which say this, then go with biomass. If I was starting again I'd say vegetation, but that's being picky - doesn't seem worth re-naming others, or introducing an inconsistency
Okay - thank you for not being picky :) :)
So we are now agreed on the following:
net_primary_productivity_of_biomass_expressed_as_carbon_accumulated_in_miscellaneous_living_matter (kg m-2 s-1)
' "Miscellaneous living matter" means all those parts of living vegetation that are not leaf, wood, root or other separately named components. The phrase "expressed_as" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. "Production of carbon" means the production of biomass expressed as the mass of carbon which it contains. Net primary production is the excess of gross primary production (rate of synthesis of biomass from inorganic precursors) by autotrophs ("producers"), for example, photosynthesis in plants or phytoplankton, over the rate at which the autotrophs themselves respire some of this biomass. "Productivity" means production per unit area.'
This name is accepted for publication in the standard name table and will be added at the next update.
27. (CMIP6 short name tSoilPools)
Chris wrote:
> OK, I agree this should be reported for each soil pool. But not all models have the same pools. We have deliberately moved away from having fast/medium and slow pools (we deleted these from the CMIP6 request) because it turned
> out from CMIP5 they simply weren't helpful. So now the request for cSoil is to report for each pool. So the decay rate should be reported for the same pools that each model reports soil carbon. It makes no sense to have decay rate
> without the soil carbon, so the two go together. What is the way that cSoilPools is being reported? This one should mirror that
Right. My understanding (based on a spreadsheet prepared by Martin) is that cSoilPools will use the existing standard name soil_carbon_content and that the data variable to which this name is attached will indeed have a soil pool dimension. So I think my general approach is the right one, but evidently we shouldn't standardize on 'fast', 'medium', 'slow' for the soil pool names if all the modelling groups are doing something different. We could use a string valued coordinate variable and allow non-standardized strings to name the pools, or maybe just index them with integers. I think it would be helpful if Martin could comment before we make any decisions.
Just to summarize, for the tSoilPools name I'm still currently suggesting:
soil_pool_carbon_decay_rate (s-1)
' "Soil carbon" is the organic matter present in soil quantified by the mass of carbon it contains. Soil carbon is returned to the atmosphere as the organic matter decays. Each modelled soil carbon pool has a characteristic turnover time, which is modified by environmental conditions such as temperature and moisture so that the turnover time varies in space and time. The quantity with standard name soil_pool_carbon_decay_rate is defined as 1/(turnover time). The data variable should be accompanied by a coordinate variable or scalar coordinate variable with standard name soil_pool.'
I had previously suggested that soil_pool should be a string valued coordinate variable, but I'm less certain about that now.
This name is still under discussion.
-- comments from Martin --
For cSoilPools we have used a string valued "soilpools" coordinate with no standardisation of the values. This is not ideal, but it follows the pattern set by the "vegtype" dimension used in CMIP5 for the landCoverFrac variable in Lmon. I have reviewed the data submitted to CMIP5, and listed the "vegtype" values used here:
https://github.com/cmip6dr/CMIP6_DataRequest_VariableDefinitions/blob/master/cmip5_landCoverUsage.xls . We have discussed how to improve this situation, but could not find a solution for "vegtype", in part because we did not want to expend disproportionate effort on a variable which was only supplied by a handful of models and because there are no complaints from users. Hence, I think we cab accept the same compromise for "soilpools", if there is no clear set of standard values to use.
------------
<
https://github.com/cmip6dr/CMIP6_DataRequest_VariableDefinitions/blob/master/cmip5_landCoverUsage.xls>
28. (CMIP6 short name co23D)
Chris wrote:
> I agree except that we should probably just drop the "passive". CO2 is passive in the chemical reaction sense that it gets advected round the atmosphere but doesn't undergo chemical reactions. But it's certainly not passive in terms
> of not affecting the rest of the model - it's a greenhouse gas and exactly why we're running the model in the first place. It very strongly affects the radiative balance of the world. So I simply suggest we remove "passive", then the rest
> looks OK.
Okay, thank you. That makes sense now! I think that leaves us with:
mass_fraction_of_carbon_dioxide_tracer_in_air (Units: 1)
'The chemical formula for carbon dioxide is CO2. Mass fraction is used in the construction "mass_fraction_of_X_in_Y", where X is a material constituent of Y. It means the ratio of the mass of X to the mass of Y (including X). A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". A "tracer" is a quantity advected by a model to facilitate analysis of flow patterns.'
Okay?
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/Centre for Environmental Data Archival Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
-----Original Message-----
From: Jones, Chris D [mailto:chris.d.jones at metoffice.gov.uk]
Sent: 04 April 2018 12:59
To: Pamment, Alison (STFC,RAL,RALSP) <alison.pamment at stfc.ac.uk>; cf-metadata at cgd.ucar.edu
Subject: RE: New standard names for C4MIP - part 2
Thanks Alison,
I think we're getting close to agreeing all of these. Comments below, but in summary:
Already agreed (so I deleted text below for brevity): 5, 6, 8, 9, 10, 12, 13, 14, 17, 18, 19, 20, 22, 23, 25, 26 Now agreed: 1, 2, 3, 4, 7, 11, 21 Still to agree: 15, 16, 24, 27, 28
Thanks,
Chris
Chris wrote:
> 1-3 are sub components of nLitter: nLitter = nLitterCwd + nLitterSurf
> + nLitterSubSurf
(nLitterCwd)
1. wood_debris_mass_content_of_nitrogen (kg m-2) ' "Content" indicates a quantity per unit area. "Wood debris" means dead organic matter composed of coarse wood. It is distinct from fine litter. The precise distinction between "fine" and "coarse" is model dependent. The sum of the quantities with standard names wood_debris_mass_content_of_nitrogen, surface_litter_mass_content_of_nitrogen and subsurface_litter_mass_content_of_nitrogen is the total nitrogen mass content of dead plant material.'
To maintain consistent syntax I think we should make an alias for the existing carbon name so that wood_debris_carbon_content becomes wood_debris_mass_content_of_carbon. This is also consistent with the creation of aliases for the existing surface and subsurface litter carbon names (see the recent discussion thread starting here:
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2018/059871.html)
Okay?
Yes - I agree this is OK
(nLitterSurf)
2. surface_litter_mass_content_of_nitrogen (kg m-2) ' "Content" indicates a quantity per unit area. "Litter" is dead plant material in or above the soil. It is distinct from coarse wood debris. "Surface litter" means the part of the litter resting above the soil surface. The precise distinction between "fine" and "coarse" is model dependent. The sum of the quantities with standard names wood_debris_mass_content_of_nitrogen, surface_litter_mass_content_of_nitrogen and subsurface_litter_mass_content_of_nitrogen is the total nitrogen mass content of dead plant material.'
Okay?
Yes - I agree this is OK
(nLitterSubSurf)
3. subsurface_litter_mass_content_of_nitrogen (kg m-2) ' "Content" indicates a quantity per unit area. "Litter" is dead plant material in or above the soil. It is distinct from coarse wood debris. "Subsurface litter" means the part of the litter mixed within the soil below the surface. The precise distinction between "fine" and "coarse" is model dependent. The sum of the quantities with standard names wood_debris_mass_content_of_nitrogen, surface_litter_mass_content_of_nitrogen and subsurface_litter_mass_content_of_nitrogen is the total nitrogen mass content of dead plant material.'
Okay?
Yes - I agree this is OK
(nStem)
4. stem_mass_content_of_nitrogen (kg m-2) ' "Content" indicates a quantity per unit area. The stem of a plant is the axis that bears buds and shoots with leaves and, at its basal end, roots. Its function is to carry water and nutrients. Examples include the stalk of a plant or the main trunk of a tree.'
I constructed this definition of 'stem' from a combination of those given at
https://www.britannica.com/science/stem-plant and
https://study.com/academy/lesson/the-plant-stem-function-types-parts.html.
Chris wrote:
> wood_biomass_content_of_nitrogen
>
>
> Yes, we mean living biomass and not dead wood (covered in nLitterCwd
> above). Hence we prefer Stem to Wood for this reason (as per carbon pool too).
I think for consistency with all the other nitrogen and carbon plant mass content names that we should say mass, rather than biomass, in this one. I've adopted your use of 'stem' instead of 'wood'. For consistency, I think we should also make an alias for the existing carbon name so that wood_carbon_content becomes stem_mass_content_of_carbon.
Okay?
Yes - I agree this is OK
(nOther)
7. miscellaneous_living_matter_mass_content_of_nitrogen (kg m-2) ' "Content" indicates a quantity per unit area. "Miscellaneous living matter" means all those parts of living vegetation that are not leaf, wood or root or other separately named components.'
Chris wrote:
> There are no other separately named pools, so nStem+nLeaf+nRoot+nOther
> should identically equal the total in nVeg (and parallel for carbon
> pools and cVeg)
I haven't added this bit into the standard name definitions in proposals 4 - 7 because the named pools of stem, leaf, root and other are defined for CMIP6 but another user of CF may potentially introduce something like nBud or nFlower, for example, so then we'd need to change the list of terms contributing to the sum.
Okay?
Yes - I agree this is OK
11. tendency_of_soil_and_vegetation_mass_content_of_nitrogen_compounds_expressed_as_nitrogen_due_to_fixation (kg m-2 s-1) 'The phrase "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. On land, "nitrogen fixation" means the uptake of nitrogen gas directly from the atmosphere. The representation of fixed nitrogen is model dependent, with the nitrogen entering either vegetation, soil or both. "Vegetation" means any living plants e.g. trees, shrubs, grass. The phrase "expressed_as" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. "Nitrogen compounds" summarizes all chemical species containing nitrogen atoms. The list of individual species that are included in this quantity can vary between models. Where possible, the data variable sh
ould be accompanied by a complete description of the species represented, for example, by using a comment attribute. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase.'
Chris wrote:
> I suggest we:
> - Say "terrestrial" instead of "soil" because this term is mainly about plants fixing nitrogen directly from N2 in the atmosphere. Some models
> may have it as a term going into the vegetation, some into the soil.
>We need to capture either/both, so it's not just the tendency of the soil nitrogen.
Thanks for the explanation - I'm suggesting 'soil_and_vegetation' to be consistent with all the other names we've introduced and I've modified the definition to explain this. Is this okay?
> - Don't specify organic/inorganic. If the fixed N goes into the vegetation it will not be in inorganic form, so again we need to leave this open
> to cover any form of uptake.
Okay - I've replaced it with "nitrogen_compounds" and a generic definition so as to cover whatever form the nitrogen takes after its uptake.
> - Don't mention anything about ammonia or diazotrophs - the terrestrial uptake doesn't go via ammonia, and I'm not sure the exact name of
> the organisms that do it are relevant.
Fine, thank you. I've changed the nitrogen fixation definition to match your explanation.
Yes - I agree this is OK now - thanks
------
(fNdep)
15. tendency_of_atmosphere_mass_content_of_reactive_nitrogen_expressed_as_nitrogen_due_to_deposition (kg m-2 s-1)
Alison wrote:
> We don't currently have any definition for 'reactive_nitrogen'. Please could you provide one?
Chris wrote:
> Basically, anything that's not N2 gas
Chris wrote:
>Is this really a new variable? I'm surprised the chemistry community don't already have nitrogen deposition?
In fact we do have an existing name tendency_of_atmosphere_mass_content_of_nitrogen_compounds_expressed_as_nitrogen_due_to_deposition
' "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. "tendency_of_X" means derivative of X with respect to time. The phrase "expressed_as" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Deposition" is the sum of wet and dry deposition. "Nitrogen compounds" summarizes all chemical species containing nitrogen atoms. Usually, particle bound and
gaseous nitrogen compounds, such as atomic nitrogen (N), nitrogen monoxide (NO), nitrogen dioxide (NO2), dinitrogen pentoxide (N2O5), nitric acid (HNO3), nitrate (NO3-), peroxynitric acid (HNO4), ammonia (NH3), ammonium (NH4+), bromine nitrate (BrONO2), chlorine nitrate (ClONO2) and organic nitrates (most notably peroxyacetyl nitrate, sometimes referred to as PAN, (CH3COO2NO2)) are included. The list of individual species that are included in this quantity can vary between models. Where possible, the data variable should be accompanied by a complete description of the species represented, for example, by using a comment attribute.'
Now that I understand the meaning of reactive_nitrogen, I think this is basically the quantity you need, except the sign convention is the opposite of what you want.
Chris wrote:
> our intended sign convention is a positive flux into vegetation, so
> this could be tendency of terrestrial nitrogen? Rather than tendency
> of the atmosphere
I suggest an alternative approach, which might sound a bit strange, but we do have a precedent for doing this. We could add the phrase "minus_one_times_" to the start of the existing name so that we are using the existing quantity but reversing the sign convention. Thus a negative tendency in the atmosphere/positive tendency in terrestrial nitrogen would have a positive numerical value. There are four existing standard names where we have reversed the sign convention in this way.
We would then have
minus_one_times_tendency_of_atmosphere_mass_content_of_nitrogen_compounds_expressed_as_nitrogen_due_to_deposition (kg m-2 s-1) ' "Minus one times" means that the quantity described takes the opposite sign convention to that for the quantity which has the same standard name apart from this phrase, i.e. the two quantities differ from one another by a factor of -1. "Content" indicates a quantity per unit area. The "atmosphere content" of a quantity refers to the vertical integral from the surface to the top of the atmosphere. For the content between specified levels in the atmosphere, standard names including "content_of_atmosphere_layer" are used. "tendency_of_X" means derivative of X with respect to time. The phrase "expressed_as" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. The sp
ecification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. "Deposition" is the sum of wet and dry deposition. "Nitrogen compounds" summarizes all chemical species containing nitrogen atoms. Usually, particle bound and gaseous nitrogen compounds, such as atomic nitrogen (N), nitrogen monoxide (NO), nitrogen dioxide (NO2), dinitrogen pentoxide (N2O5), nitric acid (HNO3), nitrate (NO3-), peroxynitric acid (HNO4), ammonia (NH3), ammonium (NH4+), bromine nitrate (BrONO2), chlorine nitrate (ClONO2) and organic nitrates (most notably peroxyacetyl nitrate, sometimes referred to as PAN, (CH3COO2NO2)) are included. The list of individual species that are included in this quantity can vary between models. Where possible, the data variable should be accompanied by a complete description of the species represented, for example, by using a comment attri
bute.'
What do you think to this approach?
Thanks for the suggestion. While this makes some sense, I think I favour sticking with the existing definition and putting up with the sign convention. This is because:
- the field is always going to have the same sign (from atmosphere to the land/ocean surface), and so if someone expects or reports it wrongly it will be instantly obvious
- therefore having one name and possible confusion over the sign is less dangerous than having two variables for essentially the same thing - this would require groups to have to process and store it twice, but simply flip the sign and re-name it. I think this causes greater confusion
- having two names carries the risk that one might somehow become different from the other which we want to avoid - we want our system to conserve, and so anything that leaves the atmosphere should enter the land/ocean
So overall I favour going with the " tendency_of_atmosphere_mass_content_of_nitrogen_compounds_expressed_as_nitrogen_due_to_deposition" name
-----
(fNfert)
16. tendency_of_soil_mass_content_of_(inorganic)_nitrogen_expressed_as_nitrogen_due_to_fertilization (kg m-2 s-1) 'The phrase "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "soil content" of a quantity refers to the vertical integral from the surface down to the bottom of the soil model. For the content between specified levels in the soil, standard names including "content_of_soil_layer" are used. The phrase "expressed_as" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. "Inorganic nitrogen" describes a family of chemical species which, in soil, usually consists of nitrate and ammonium compounds which act as nitrogen nutrients. "Fertilization" means the addition of artificial fertilizers and animal manure to soil for the
purpose of increasing plant nutrient concentrations(, and could by model choice be either into nSoil or nMineral pools).'
Alison wrote:
>Is it right to say 'inorganic_nitrogen' for this one? Is the definition of 'fertilization' okay?
Chris wrote:
> Yes - definition of fertilisation is OK.
> No - it doesn't have to be inorganic. Again this might differ by
> model, and we just want to capture how much N is going into the system. I've suggested we should also be specific that it includes either organic or inorganic pool in case the term "tendency of soil mass content of nitrogen"
> is taken to refer to nSoil and not nMineral.
Thanks for the additional explanation. We shouldn't refer to nSoil and nMineral in the definition as these are only defined for CMIP6 - we need to make the names and definitions useful to all CF users. (However, this has helped me to understand the quantity better.) In the first group of C4MIP names we agreed soil_mass_content_of_inorganic_nitrogen_expressed_as_nitrogen, where the 'inorganic_nitrogen' was the phrase we chose to describe mineral nitrogen, nMineral. From your description I now understand nSoil to mean the organic nitrogen in the soil - is that right? To be consistent with the terminology in the existing name and to capture the full meaning of this new one, we could call it:
tendency_of_soil_mass_content_of_organic_and_inorganic_nitrogen_expressed_as_nitrogen_due_to_fertilization (kg m-2 s-1) 'The phrase "tendency_of_X" means derivative of X with respect to time. "Content" indicates a quantity per unit area. The "soil content" of a quantity refers to the vertical integral from the surface down to the bottom of the soil model. For the content between specified levels in the soil, standard names including "content_of_soil_layer" are used. The phrase "expressed_as" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. "Inorganic nitrogen" describes a family of chemical species which, in soil, usually consists of nitrate and ammonium compounds which act as nitrogen nutrients. "Organic nitrogen" consists of all organic nitrogen compounds in the soil. "Fertilization
" means the addition of artificial fertilizers and animal manure to soil for the purpose of increasing plant nutrient concentrations.'
We could alternatively say nitrogen_compounds_expressed_as_nitrogen as we have in other names and emphasise in the definition that for this name it means the inorganic nutrients plus the organic compounds in the soil itself.
I tend to think the first one might be clearer but I'd be happy with either approach - which do you prefer?
Thanks for the options - I think I favour not saying "organic and inorganic" in the name, and just going with " nitrogen_compounds_expressed_as_nitrogen". This seems simpler and the former doesn't add anything extra I don't think.
----
Chris wrote:
> 21-23, combines with raOther to sum to give total autotrophic respiration:
> ra = raStem + raLeaf + raRoot + raOther
(raStem)
21. surface_upward_mass_flux_of_carbon_due_to_plant_respiration_in_stems (kg m-2 s-1) '
"Upward" indicates a vector component which is positive when directed upward (negative downward). In accordance with common usage in geophysical disciplines, "flux" implies per unit area, called "flux density" in physics. The specification of a physical process by the phrase "due_to_" process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase. Plant respiration is the sum of respiration by parts of plants both above and below the soil. Plants which photosynthesise are autotrophs i.e. "producers" of the biomass which they respire from inorganic precursors using sunlight for energy. The stem of a plant is the axis that bears buds and shoots with leaves and, at its basal end, roots. Its function is to carry water and nutrients. Examples include the stalk of a plant or the main trunk of a tree.'
As for proposal (4) I've changed this one to say 'stem' instead of 'wood'. Okay?
Yes - I agree this is OK
-----
Chris wrote:
> 24, combine with other npp components to sum to give total npp:
> npp = nppStem + nppLeaf + nppRoot + nppOther
(nppOther)
24. net_primary_productivity_of_biomass_expressed_as_carbon_accumulated_in_miscellaneous_living_matter (kg m-2 s-1) ' "Miscellaneous living matter" means all those parts of living vegetation that are not leaf, wood, root or other separately named components. The phrase "expressed_as" is used in the construction A_expressed_as_B, where B is a chemical constituent of A. It means that the quantity indicated by the standard name is calculated solely with respect to the B contained in A, neglecting all other chemical constituents of A. "Production of carbon" means the production of biomass expressed as the mass of carbon which it contains. Net primary production is the excess of gross primary production (rate of synthesis of biomass from inorganic precursors) by autotrophs ("producers"), for example, photosynthesis in plants or phytoplankton, over the rate at which the autotrophs themselves respire some of this biomass. "Productivity" means production per unit area.'
Chris wrote:
> OK - but suggest "of vegetation" rather than "of biomass"
There are eleven existing net_primary_productivity_of_biomass names so I used biomass in this one for consistency. It also allows us to maintain consistency across ocean and atmosphere names. We could change all the land based ones to say 'vegetation' and I can see that might be an improvement, particularly as biomass can also mean dead plant material, e.g, biomass fuel. However, I do also think the overall consistency in the standard names is useful. Do you have a strong preference for 'vegetation' or could you live with 'biomass' for this one?
OK, if there are other variables which say this, then go with biomass. If I was starting again I'd say vegetation, but that's being picky - doesn't seem worth re-naming others, or introducing an inconsistency
---
(tSoilPools)
27. soil_pool_carbon_decay_rate (kg m-2 s-1) ' "Soil carbon" is the organic matter present in soil quantified by the mass of carbon it contains. Soil carbon is returned to the atmosphere as the organic matter decays. The decay process takes varying amounts of time depending on the composition of the organic matter, the temperature and the availability of moisture. A carbon "soil pool" means the carbon contained in organic matter which has a characteristic period over which it decays and releases carbon into the atmosphere.'
Alison wrote:
> This is a new quantity, although we do have some existing names that refer to soil_pools. I guessed the unit from the quantity - is it correct?
Chris wrote:
> This quantity is meant to complement the respiration one and give the
> turnover rate, hence units simply "per second, s-1". Each modelled
> soil carbon pool will have a characteristic turnover time, which is
> then modified by environmental conditions such as temperature and moisture so that the turnover time varies in space and time. Hence it is requested as a new variable. We request here the turnover RATE rather than TIME, defined as 1/(turnover time). Use the same pools reported under cSoilPools.
Okay, thank you for the explanation. Since a different rate can be applied to each of the fast, medium and slow pools I think you would also need to supply a coordinate variable or scalar coordinate variable alongside the data variable to label which pool the rate applies to. Such a variable could have a standard name of soil_pool and could take either a single string value chosen from 'fast', 'medium', 'slow' or an array of those strings if you wanted to store several rates in an data array with a soil pool dimension. All of this would need to be explained in the definition, so for the rates themselves we'd have:
soil_pool_carbon_decay_rate (s-1)
' "Soil carbon" is the organic matter present in soil quantified by the mass of carbon it contains. Soil carbon is returned to the atmosphere as the organic matter decays. Each modelled soil carbon pool has a characteristic turnover time, which is modified by environmental conditions such as temperature and moisture so that the turnover time varies in space and time. The quantity with standard name soil_pool_carbon_decay_rate is defined as 1/(turnover time). The data variable should be accompanied by a coordinate variable or scalar coordinate variable with standard name soil_pool and whose value(s) are chosen from a standardised list.'
Then we'd also create a new standard name for the coordinate variable:
soil_pool (NO units because it takes a string value) A variable with the standard name of soil_pool contains strings which indicate the nature of the soil pool itself classified according to the decay rate of the organic carbon material it contains. These strings are standardised. The value(s) must be chosen from the list: fast; medium; slow.
What do you think?
OK, I agree this should be reported for each soil pool. But not all models have the same pools. We have deliberately moved away from having fast/medium and slow pools (we deleted these from the CMIP6 request) because it turned out from CMIP5 they simply weren't helpful. So now the request for cSoil is to report for each pool. So the decay rate should be reported for the same pools that each model reports soil carbon. It makes no sense to have decay rate without the soil carbon, so the two go together. What is the way that cSoilPools is being reported? This one should mirror that
---
(co23D)
28. mass|mole_concentration_of_carbon_dioxide_passive_tracer_in_air
Alison wrote:
> What are the units of this quantity? Knowing the unit will allow us to decide if this should be a mass or a mole concentration (or something else).
> I wasn't really sure of the purpose of this name - by using carbon
> dioxide as a tracer I assume that means it is conserved by being treated as chemically inert. Can you give me some more details about this one please?
Chris wrote:
> This is requested to be a mass mixing ratio in kg CO2 / kg dry air.
> Report 3D field of model simulated atmospheric CO2 mass mixing ration on model levels.
Okay, so the name should then be:
mass_fraction_of_carbon_dioxide_passive_tracer_in_air (Units: 1 (because it's kg kg-1)) ' The chemical formula for carbon dioxide is CO2. Mass fraction is used in the construction "mass_fraction_of_X_in_Y", where X is a material constituent of Y. It means the ratio of the mass of X to the mass of Y (including X). A chemical species denoted by X may be described by a single term such as "nitrogen" or a phrase such as "nox_expressed_as_nitrogen". A "passive tracer" is a quantity advected by a model to facilitate analysis of flow patterns. It has no effect on any of the model's processes and only the model's dynamical processes affect the tracer.'
(The definition of passive_tracer is new to standard names).
Okay?
I agree except that we should probably just drop the "passive". CO2 is passive in the chemical reaction sense that it gets advected round the atmosphere but doesn't undergo chemical reactions. But it's certainly not passive in terms of not affecting the rest of the model - it's a greenhouse gas and exactly why we're running the model in the first place. It very strongly affects the radiative balance of the world. So I simply suggest we remove "passive", then the rest looks OK.
Best wishes,
Alison
------
Alison Pamment Tel: +44 1235 778065
NCAS/Centre for Environmental Data Archival Email: alison.pamment at stfc.ac.uk
STFC Rutherford Appleton Laboratory
R25, 2.22
Harwell Oxford, Didcot, OX11 0QX, U.K.
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Received on Thu Apr 05 2018 - 01:24:51 BST
