Difference between revisions of "Talk:Units"
Line 32: | Line 32: | ||
=='''<font color="Red">CTextor (CT) / Martin Schultz (MS) / Sebastian Rast (RS): UDUNITS in atmospheric chemistry: time issues</font>'''== | =='''<font color="Red">CTextor (CT) / Martin Schultz (MS) / Sebastian Rast (RS): UDUNITS in atmospheric chemistry: time issues</font>'''== | ||
*'''MS:''' (translated from german by ct) The use of non-UDUNITS can be of advantage, if it concern a variable that is integrated over a certain period, e.g. a the dry deposition flux over a month would need to have mole/m2/month. This is not the same as a mean dry dep. which could be given in mole/m2/s. | *'''MS:''' (translated from german by ct) The use of non-UDUNITS can be of advantage, if it concern a variable that is integrated over a certain period, e.g. a the dry deposition flux over a month would need to have mole/m2/month. This is not the same as a mean dry dep. which could be given in mole/m2/s. | ||
− | *'''CT:''' (corrected) I think the cell method of CF should be applied here | + | *'''CT:''' (corrected) I think the cell method of CF should be applied here, question asked to Jonathan Gregory |
dimensions:<BR> | dimensions:<BR> |
Revision as of 10:28, July 3, 2006
|
UDUNITS have to be used for the standard_names according to the CF convention. This is however not always obvious for chemistry and aerosol variables, where also other units are common. This page provides a discussion on this matter. See also Unidata Supported Units || Unit Converter, UDUNITS
Important issues are marked in RED , please COMMENT!
Agreed items of former discussions on the "Units" page can be found here.
JGregory: Don't mix units with the Compound
However, kgC and kgS aren't SI units. I think the unit has to be kg. This implies that it's the standard name which must somehow indicate that it is the mass of C or mass of S which is being referred to, rather than the mass of the compound e.g. dry_deposition_flux_of_sulfur_as_sulfate_at_surface. --JonathanGregory 16:51, 22 May 2006 (EDT)
......CTextor:
- Very good idea, I will change this. --Christiane Textor (Christiane) 17:11, 2 June 2006 (EDT)
CTextor: SI units
- Try to use SI units if allowed within udunits (e.g. not hours but seconds) --Christiane Textor (Christiane) 12:11, 2 June 2006 (EDT)
RanjeetSokhi(RS) / CTextor (CT): remarks on version June 12 from RS and answers from CT
- RS: Table 1 mass_concentration is usually stated in ug/m3 ie micrograms per cubic metre - this is conventional and used in all air quality literature (scientific and policy)
- CT: --Christiane Textor (Christiane) 13 June 2006 (EDT)
CTextor (CT) / Martin Schultz (MS) / Sebastian Rast (RS): UDUNITS in atmospheric chemistry: concentration
- CT: usually the concentration of chemical compound are not given in UDUNITS, see the remark of Ranjeet above for the air quality community, where aerosol mass_concentration is usually stated in ug/m3ich, or the global chemistry community where the tropospheric column of a gas is given in [molec/cm2], and the dry deposition in [g/m2/month]. This should be changed
- cm2 -> m2
- molec -> mole
- g -> kg
- We had a discussion (in german) that this would be difficult, because all papers are in the non-udunits, but at the same time it would be good to agree on one standard within GEMS and HTAP.
CTextor (CT) / Martin Schultz (MS) / Sebastian Rast (RS): UDUNITS in atmospheric chemistry: time issues
- MS: (translated from german by ct) The use of non-UDUNITS can be of advantage, if it concern a variable that is integrated over a certain period, e.g. a the dry deposition flux over a month would need to have mole/m2/month. This is not the same as a mean dry dep. which could be given in mole/m2/s.
- CT: (corrected) I think the cell method of CF should be applied here, question asked to Jonathan Gregory
dimensions:
- lat = 18 ;
- lon = 36 ;
- pres = 15 ;
- time = UNLIMITED ;//(2 currently
variables:
- float drydep_SO2(time,pres,lat,lon) ;
- ddep_SO2:standard_name = "dry_deposition_flux_due_to_turbulence_of_sulfur_dioxide_at_surface" ;
- ddep_SO2:units = "mole/m2/s" ;
- ddep_SO2:cell_methods="time: sum (over month)"
- ddep_SO2:standard_name = "dry_deposition_flux_due_to_turbulence_of_sulfur_dioxide_at_surface" ;
- float lon(lon) ;
- lon:long_name = "longitude" ;
- lon:units = "degrees_east" ;
- lon:long_name = "longitude" ;
- float lat(lat) ;
- lat:long_name = "latitude" ;
- lat:units = "degrees_north" ;
- lat:long_name = "latitude" ;
- float pres(pres) ;
- pres:long_name = "pressure" ;
- pres:units = "hPa" ;
- pres:long_name = "pressure" ;
- double time(time) ;
- time:long_name = "time" ;
- time:units = "days since 1990-1-1 0:0:0" ;
- time:bounds = "time_bnds";
- time:long_name = "time" ;
- double time_bnds(time,nv);
data:
- time = 1., 2.;
- time_bnds = 0.,1.,1.,2.;