Open jypeter opened 6 years ago
The table below gives alternating lines of current variable definitions in DR 01.00.22 and the new requested definitions, and the first column gives either the row number of the variable in the DR 01.00.22 Emon variables, or updated to show the new values, or NEW for the 2 new variables
The following columns are not changed (or were replicated, in the case of the 2 new variables) and were not included in the summary table below: _priority, cell_methods, positive, type, dimensions, modeling_realm, frequency, cellmeasures
The columns from prov to MIPs (by experiment) that are more internal DR stuff were not included either
The xlsx version of the table below is available in CMIP6_MIP_tables_DR22vsRoche_subset.xlsx (and a version without the extra columns removed is available in CMIP6_MIP_tables_DR22vsRoche.xlsx)
Line in DR22 Emon | Long name | units | description | comment | Variable Name | CF Standard Name | CMOR Name |
---|---|---|---|---|---|---|---|
280 | 18O in total precipitation | Roche - LSCE | O18p | missing | O18p | ||
updated | H218O in precipitation | kg m-2 s-1 | Ratio of 18O in precipitation, includes both liquid and solid phases | at surface; includes both liquid and solid phases from all types of clouds (both large-scale and convective) | pr18O | precipitation_flux_H218O | pr18O |
281 | 18O in solid precipitation | Roche - LSCE | O18s | missing | O18s | ||
updated | H218O in snowfall flux | kg m-2 s-1 | Ratio of 18O in solid precipitation, includes solid phases only | at surface; includes precipitation of all forms of water in the solid phase | prsn18O | snowfall_flux_H218O | prsn18O |
282 | 2H in total precipitation | Roche - LSCE | H2p | missing | H2p | ||
updated | 1H2HO in precipitation | kg m-2 s-1 | Ratio of 2H in precipitation, includes both liquid and solid phases | at surface; includes both liquid and solid phases from all types of clouds (both large-scale and convective) | pr2h | precipitation_flux_1H2HO | pr2h |
283 | 2H in solid precipitation | Roche - LSCE | H2s | missing | H2s | ||
updated | 1H2HO in snowfall flux | kg m-2 s-1 | Ratio of 2H in solid precipitation, includes solid phases only | at surface; includes precipitation of all forms of water in the solid phase | prsn2h | snowfall_flux_1H2HO | prsn2h |
284 | 17O in total precipitation | Roche - LSCE | O17p | missing | O17p | ||
updated | H217O in precipitation | kg m-2 s-1 | Ratio of 17O in precipitation, includes both liquid and solid phases | at surface; includes both liquid and solid phases from all types of clouds (both large-scale and convective) | pr17O | precipitation_flux_H217O | pr17O |
285 | 17O in solid precipitation | Roche - LSCE | O17s | missing | O17s | ||
updated | H217O in snowfall flux | kg m-2 s-1 | Ratio of 17O in solid precipitation, includes solid phases only | at surface; includes precipitation of all forms of water in the solid phase | prsn17O | snowfall_flux_H217O | prsn17O |
286 | O18 in water vapor | Roche - LSCE | O18wv | missing | O18wv | ||
updated | H2O18 in water vapor | kg m-2 | Ratio of 18O in atmospheric water vapor | ideally, provided on all vertical levels | prw18O | atmosphere_water_vapor_content_H218O | prw18O |
287 | O17 in water vapor | Roche - LSCE | O17wv | missing | O17wv | ||
updated | H2O17 in water vapor | kg m-2 | Ratio of 17O in atmospheric water vapor | ideally, provided on all vertical levels | prw17O | atmosphere_water_vapor_content_H217O | prw17O |
288 | H2 in water vapor | Roche - LSCE | H2wv | missing | H2wv | ||
updated | 1H2HO in water vapor | kg m-2 | Ratio of 2H in atmospheric water vapor | ideally, provided on all vertical levels | prw2H | atmosphere_water_vapor_content_1H2HO | prw2H |
318 | O18 in sea water | Roche - LSCE | O18sw | missing | O18sw | ||
updated | H2O18 in sea water | 1 | Ratio of 18O in sea water | sw18O | sea_water_H218O | sw18O | |
NEW | H2O17 in sea water | 1 | Ratio of 17O in sea water | sw17O | sea_water_H217O | sw17O | |
NEW | 1H2HO in sea water | 1 | Ratio of 2H in sea water | sw2H | sea_water_1H2HO | sw2H |
Do the units imply a mass flux of water molecules that contain the given isotope (e.g., mass of H2O containing an O18 atom) or is it the mass flux of the atom itself (e.g., mass of O18 contained in precipitation)?
If these really are ratios, I presume it is the ratio of water containing a given isotope to all the water (e.g., ratio of mass of precipitation containing O18 to total precipitation).
The descriptions and possibly the units need revision to make it clear.
In addition the standard names don't follow current CF patterns, which include, for example: litter_mass_content_of_13C and mass_content_of_13C_in_vegetation_and_litter_and_soil_and_forestry_and_agricultural_products
Finally, the "Name in Data Request", and the "Variable Name" should almost always be the same.
thanks.
I presume from the above discussion that the name is wrong, not the unit itself. Indeed, what I had in mind and what is done in most models (to my knowledge) is to output the water mass flux (hence kg.m-2.s-1) times the ratio.
In short, the ratio is generally computed as (using precipitation as an example): 18R_prc = pr18O / pr
Hence the unit of pr18O should be a mass flux. I thus conclude that the correct name should be "a mass flux of water molecules that contain the given isotope".
For the ocean, it is a ratio of the given isotope in seawater, since there is nothing like the mass of water in a given cell and hence the unit is correctly "None" or "1".
From the above, I would keep the short name and unit but adjust the long name I think.
Best wishes, Didier
Thanks @dmr-dj , that makes the intentions clear.
For pr18O we could use "Precipitation mass flux of water molecules that contain the oxygen-18 isotope (180), including solid and liquid phases. Sometimes known as heavy-oxygen water."
I'd like to change the long name, because the term "H218O" could be confusing to someone who doesn't know the context. Can we use the term "heavy-oxygen water", e.g. "Heavy-Oxygen Water Precipitation Flux"?
Similarly for "1H2HO", can we refer to "Semi-heavy water", e.g. "Semi-heavy Water Precipitation Flux"?
As Karl has mentioned, we also need to develop some new standard names for these variables, but I'd like to discuss that with Alison Pamment before discussing it further here. regards, Martin
On the long name point, @martinjuckes : I do not like the long name suggested. It would not appeal at all to the water isotope community I think. Potentially, we could discuss in the future double-substituted water isotopes such as HD18O, what would then be the name? Also, how do you place the H217O in this frame? If H218O is heavy and HDO is semi-heavy, then H217O is ... "almost heavy"? This is way too imprecise I think.
I am not attached to a particular form of the long name, but it should be clear that we are referring to water with a single heavier substitute atom, being 18O, 17O or 2H (=D).
Best wishes, Didier
OK, @dmr-dj , in other long names we have put chemical formulae in brackets for clarification, but I would like to have some words to convey the meaning as well. e.g. (i) Precipitation Flux of Water containing Oxygen-18 (H2 18O) or (ii) Oxygen-18 Water Precipitation Flux (H2 18O)
Do either of these make sense?
I've put some modified long names and descriptions into https://docs.google.com/spreadsheets/d/1vcHdcfhW423aqg8LCuMTBACB5-JUrVuxDV7s52XJm6I/edit#gid=0 .. based on our discussion above ... please check that they are OK. I've also added some draft standard names, which follow existing standard name patterns as far as possible. I'll discuss these with Alison next week and get them posted to the CF discussion list for approval.
One question for @taylor13 : the proposed revision of the variable names (O18p --> pr18O etc) would go against the WIP decision to fix all variable names, but these variables are highly specialised and unlikely to have been produced by the initial model runs completed so far -- so we could consider allowing an exception here (I've checked with @senesis , and he has confirmed that IPSL have not produced these variables yet). Should we stick to the old names or allow an exception? There are also two new variables which somehow got omitted from the original request ... I think we could add these (sw17O, sw2H -- the last 2 rows).
The updated Description
and CF Standard Name
fields can be found in the PMIP Standard names: isotopic fluxes, mass contents and ratios proposal that @martinjuckes sent to the CF-metadata mailing list
@martinjuckes can we leave the Long name
and Comment
fields as they were proposed in https://github.com/cmip6dr/CMIP6_DataRequest_VariableDefinitions/issues/316#issuecomment-373428076 ?
Hello @jypeter , I'd prefer to use the long names I've suggested in my comment on April 29th above [ https://github.com/cmip6dr/CMIP6_DataRequest_VariableDefinitions/issues/316#issuecomment-377205460 ]. The one that you have suggested in https://github.com/cmip6dr/CMIP6_DataRequest_VariableDefinitions/issues/316#issuecomment-373428076 are a bit too brief and technical for my taste.
@dmr-dj : we need some clarification on sw2h
: you have long name implying that it is the ration of 1H.2H.O molecules to 1H2.O molecules (i.e. ratio of number of molecules with a single deuterium to the number of molecules with two base state hydrogen atoms) and a description which suggests that it is the ratio of 2H atoms to 1H atoms in sea water: which of these interpretations is correct?
Hello @dmr-dj , @jypeter : we need to finalise definition of variables for CMIP6: unless I hear otherwise I'll assume that s2wh is an isotope ratio (i.e. ratio of 2H atoms to 1H atoms) rather than a molecular composition ratio (i.e. ratio of 2H.H.O to H2O).
This thread will be used to update the oxygen and hydrogen isotope ratios in the PMIP part of Emon, aka Roche variables because they were requested by Didier Roche (@dmr-dj) and the content of the description column was Roche - LSCE up to DR 01.00.22
This will address the missing units problem mentioned in #275
Note that there are 10 Roche variables in DR 01.00.22, but 2 variables are missing: we need a total of 12 variables in order to cover
{ 18O, 2H, 17O } x { precip, solid precip, water vapor, sea water }
=> 3 x 4 variablesThe list of updated variables is available in CMIP6_MIP_tables_Roche-O-H-Isotope.xlsx and I will try to find a clean way to list the required changes in the next part of this issue