wmo-im
Add 'accumulated precipitation' to atmospheric variables (1-01-01)
Initial request
Accumulated precipitation was updated in OSCAR/Requirements in the summer of 2024. The initial request is to add 'accumulated precipitation' to the WIGOS atmospheric variables (1-01-01).
Requestor(s)
GCOS, OSCAR Requirements, @kpremec
Stakeholder(s)
Enter list of stakeholder(s).
Applications or Systems
- [X] OSCAR/Surface
- [X] OSCAR/requirements
- [ ] Radar/DB
- [ ] OceanOPS
- [ ] WHOS
- [ ] WDQMS
- [ ] GBON Compliance Monitor
- [ ] Other
Expected impact of change
LOW
Collaborators
David Berry provides two alternative sources essentially in support of the existing WMO code 210.
References
https://space.oscar.wmo.int/variables/view/accumulated_precipitation https://codes.wmo.int/wmdr/ObservedVariableAtmosphere/210
Comments
This is similar to Amount of precipitation which does not have a definition yet. A definition was added. OSCAR/Requirements is invited to adopt the existing code 210 (Amount of precipitation).
Publication(s)
Example: Manual on Codes (WMO-No. 306), Volume I.3, WMO Codes Registry, Code table 1-01-01
Validation
No response
Amendment details
last updated 17 Jan 2025
Instead of introducing a new term, the existing variable 210 is amended with a definition.
| Notation | Name | Description |
|---|---|---|
| 210 | Amount of precipitation | The amount, usually expressed in millimeters or inches of liquid water depth, of the water substance that has fallen at a given point over a specified period of time. (source: AMS Glossary, https://glossary.ametsoc.org/wiki/Precipitation) |
https://github.com/wmo-im/tt-wigosmd/wiki/Meeting.2024.10.24 notes: @joergklausen taking responsiblity
The proposed variable is indeed synonymous to the existing variable (210). The following description is proposed:
"The amount, usually expressed in millimeters or inches of liquid water depth, of the water substance that has fallen at a given point over a specified period of time. (source: AMS Glossary, https://glossary.ametsoc.org/wiki/Precipitation)
It is suggested for the OSCAR/Space platform to adopt the name 'Amount of precipitation'.
https://github.com/wmo-im/tt-wigosmd/wiki/Meeting.2024.11.21 notes: Joerg presented proposal as in comments above
See https://hydro.geodab.eu/hydro-ontology/concept/65 for the equivalent in the WHOS ontology.
We also have the CF convention definition, see https://vocab.nerc.ac.uk/standard_name/precipitation_amount/
hydro-ontology uses the existing term, but does not provide a definition. The NERC name is consistent with WIGOS, but does not have the notion of time period, which I consider important. Since no negative feedback was received, I have updated the proposal as presented on 20 Nov 2024.
https://github.com/wmo-im/tt-wigosmd/wiki/Meeting.2025.01.16 notes:
- Joerg recommends adding a definition to "Amount of precipitation", the definition is from AMS glossary
- @joergklausen update branch
- @amilan17 coordinate feedback to EOSDE;
It is advised to be consistent with the definition of precipitation in the cloud atlas (https://cloudatlas.wmo.int/en/glossary.html#P)
@kpremec will review WMO publications
It is advised to be consistent with the definition of precipitation in the cloud atlas (https://cloudatlas.wmo.int/en/glossary.html#P)
@kpremec will review WMO publications
The reference is not helpful for the definition of amount of precipitation. The proposed definition appears to be consistent with the definition of 'precipitation' in the cloud atlas. What change is requested?
https://github.com/wmo-im/tt-wigosmd/wiki/Meeting.2025.02.20 notes: @amilan17 will see if Kruno has feedback
@kpremec Could you please comment, so that we can advance with this? Thanks very much.
@joergklausen please see below some definitions. General comment to the proposed (AMS) definiton, we should not promote non-SI units (inches).
WMO-No. 8: Precipitation - the liquid or solid products of the condensation of water vapour falling from clouds, in the form of rain, drizzle, snow, snow grains, snow pellets, hail and ice pellets; or falling from clear air in the form of diamond dust.
WMO-No. 407 = UNTERM = WMO-No. 182 Precipitation - A hydrometeor consisting of a fall of an ensemble of particles. The forms of precipitation are: rain, drizzle, snow, snow grains, snow pellets, diamond dust, hail and ice pellets.
WMO-No. 8: Amount of precipitation - amount reaches the ground in a stated period, expressed in terms of the vertical depth of water (or water equivalent in the case of solid forms) to which it would cover a horizontal projection of the Earth’s surface.
I prefer this one, with a minor modification as follows: Accumulated precipitation = amount of precipitation reaches the surface in a stated period, expressed in terms of the vertical depth of water (or water equivalent in the case of solid forms) to which it would cover a horizontal projection of the Earth’s surface.
"Surface" is more appropriate than "ground".
I personally do not have any strong objections if this quantity is called "accumulated precipitation" or "amount of precipitation", however, the former one seems to be a bit more "elegant".
Accumulated precipitation is amount of precipitation ... Amount of precipitation is amount of precipitation ...
Based on the discussion above, the following is proposed. The name "Amount of precipitation" has been retained simply to avoid a change with potential side-effects. I have no personal strong feelings for either term.
| Notation | Name | Description |
|---|---|---|
| 210 | Amount of precipitation | Precipitation that reaches the surface in a stated period, expressed in terms of the vertical depth of water (or water equivalent in the case of solid precipitation) to which it would cover a horizontal projection of the Earth’s surface. Modified from: WMO-No. 8 |
Notation Name Description 210 Amount of precipitation Precipitation that reaches the surface in a stated period, expressed in terms of the vertical depth of water (or water equivalent in the case of solid precipitation) to which it would cover a horizontal projection of the Earth’s surface. Modified from: WMO-No. 8
This definition is different from OSCAR Requirements for 'accumulated precipitation'
Integration of solid and liquid precipitation rate reaching the ground over a time period defined in the metadata.
@kpremec do you propose to update the O/R definition to align with the proposed WIGOS definition?
https://github.com/wmo-im/tt-wigosmd/wiki/Meeting.2025.09.18 notes: Waiting for Kruno's confirmation on behalf of EOSDE of the definition above, Kruno agrees to the definition, but thinks "accumulated" and "amount" definitions are equivalent.
@meulenvd to help review
Caterina (WMO Secretariat) will try to have a response available for November meeting
For me, the proposed definition is OK. I checked the TechRegs (WMO-No. 49 Vol I) and the Manual to the WIGOS (WMO-N0. 1160) and I found no conflicts. I like in particular the addition "to which it would cover a horizontal projection of the Earth’s surface", which is not trivial. In the Man. to the WIGOS "accumulated" and "amount" is used both for the same quantity. In the obsolete Man. to the GOS (WMO-No. 544) it was only stated 3.3.8.1 The amount of precipitation shall be the sum of the amounts of liquid precipitation and the liquid equivalent of solid precipitation (not copied to the Man. to the WIGOS, but now reference is made to GIMO, WMO-No. 8). In the Man. to the WIGOS a remark is stated for Precipitation, Amount: Expressed in the liquid equivalent {Mass/area} or (Volume/area}. May be derived from continuous measurement of intensity of precipitation; if less than 0.01 mm, it should be indicated as “trace". "Volume/area" equals to "length" (=depth of water [equivalent]) in mm. When expressing as "Mass/area" in kg m-2 it is commonly converted into "Volume/area" assuming a density of 1 kg / 1 dm3 for all temperatures because the resulting error is less than the required measurement uncertainty (not stated in Man. to the WIGOS, but described in the GIMO)
