Dear Martin and Jonathan,
Just picking up on this thread again - this is the 3rd (and final) group of LS3MIP names remaining to be resolved.
We have now received clarification of how various parts of the land liquid water and ice budget are calculated, which I copy below so that we have a record in this public discussion:
> 1) If we preferentially focus on mass balance, it would be straightforward to have:
> + soil moisture : total water in soil column
> + water table depth : depth of saturation
> + groundwater recharge : water flux at water table (which should be base flow if water table depth is lower than model soil depth)
>
> 2) In terrestrial hydrology, cold processes and associated storage are treated with liquid phase processes in general.
> Therefore, it would be more useful to have them in separated variables.
>
> 3) I mostly agree with you suggestion, but because of reason 2), it would be better to be defined as (although it is same to yours
> physically) summation of:
> + liquid phase surface water (water in rivers, wetlands, lakes, vegetation, reservoirs, canopy interception)
> + snow (&canopy interception), and ice, including grounded ice sheets and ice on lakes etc, but excluding ice shelves floating in sea water
> + liquid subsurface water
> + solid subsurface water
Many thanks to Hyungjun Kim for clarifying these important questions.
I have used this explanation to finish writing definitions for these names. I think most of the terms could now be accepted if you are happy with the definitions. I have a question as to whether proposals 1.5 and 1.8 should really include floating ice shelves, which seem to be explicitly excluded in Hyungjun's text.
> 1.2 CMIP6 short name dgw. Change in Groundwater We do not currently
>have any terms specifically for groundwater, so this concept needs to be defined: the following is proposed: "Groundwater is the subsurface water in the saturated zone."
>
> + propose: change_over_time_in_groundwater_amount (kg m-2)
>From Hyungjun's description I have defined groundwater as 'Groundwater is subsurface water below the depth of the water table.' This then gives us the following definition for the proposed term:
'The phrase "change_over_time_in_X" means change in a quantity X over a time-interval, which should be defined by the bounds of the time coordinate. "Water" means water in all phases. Groundwater is subsurface water below the depth of the water table. "Amount" means mass per unit area.'
Okay?
> 1.3 CMIP6 short name drivw. Change in River Storage There is no
> existing term for the amount of water in rivers, though there are
> several for the rate of flow. Such terms as exist make no explicit reference to the definition of the what is meant by river water, so a clarification note is proposed.
>
> + Propose: change_over_time_in_river_water_amount (kg m-2) "River
> + water amount refers to the water in the fluvial system (stream and floodplain)".
For the river flow names, we decided that they include water in all phases (
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2018/020241.html, proposal 5), therefore I assume this one does too. Hence the definition would be:
'The phrase "change_over_time_in_X" means change in a quantity X over a time-interval, which should be defined by the bounds of the time coordinate. "Water" means water in all phases. "River" refers to the water in the fluvial system (stream and floodplain). "Amount" means mass per unit area.'
Okay?
> 1.5 CMIP6 short name dsn. Change in snow water equivalent (including
> snow and ice)
>
> The ice includes all the ice above ground, including glaciers, ice sheets and floating ice shelves.
>
> + Propose: change_over_time_in_surface_snow_and_ice_amount (kg m-2)
The 'ice_and_snow_on_land' definition we agreed in
http://mailman.cgd.ucar.edu/pipermail/cf-metadata/2018/020250.html for the nudging standard name and area_type seems a better fit to the proposed quantity than land_ice because it includes river and lake ice, as well as snow.
Hence I am changing my suggestion for this name to be:
change_over_time_in_amount_of_ice_and_snow_on_land (kg m-2)
'The phrase "change_over_time_in_X" means change in a quantity X over a time-interval, which should be defined by the bounds of the time coordinate. "Amount" means mass per unit area. The phrase "ice_and_snow_on_land" means ice in glaciers, ice caps, ice sheets & shelves, river and lake ice, any other ice on a land surface, such as frozen flood water, and snow lying on such ice or on the land surface.'
This name and definition agree with the original proposal, but I note that Hyungjun's text says 'excluding ice shelves floating in sea water' in the second bullet of point (3). Are we sure that this CMIP dsn variable should include ice shelves?
> 1.6 CMIP6 short name dsw. Change in Surface Water Storage Surface
> water storage is interpreted as terrestrial water storage, which has a recently discussed name land_water_amount.
>
> + Propose: change_over_time_in_land_water_amount (kg m-2)
Hyungjun's description of all land water components says:
> + liquid phase surface water (water in rivers, wetlands, lakes, vegetation, reservoirs, canopy interception)
> + snow (&canopy interception), and ice, including grounded ice sheets and ice on lakes etc, but excluding ice shelves floating in sea water
> + liquid subsurface water
> + solid subsurface water
Hence, I would write the definition of land_water_amount (proposed for PMIP) as:
' "Amount" means mass per unit area. "Water" means water in all phases. The quantity with standard name land_water_amount, often known as "Terrestrial Water Storage", includes surface liquid water (water in rivers, wetlands, lakes, reservoirs, rainfall intercepted by the canopy), surface ice and snow (glaciers, ice caps, grounded ice sheets, river and lake ice and other surface ice such as frozen flood water, snow lying on the surface and intercepted by the canopy) and subsurface water (liquid and frozen soil water, groundwater).'
(This PMIP name can now also be accepted if you are happy with the definition. N.B. It excludes floating ice shelves).
Following on from this, the proposed name would be:
change_over_time_in_land_water_amount (kg m-2)
'The phrase "change_over_time_in_X" means change in a quantity X over a time-interval, which should be defined by the bounds of the time coordinate. "Amount" means mass per unit area. "Water" means water in all phases. The quantity with standard name land_water_amount, often known as "Terrestrial Water Storage", includes surface liquid water (water in rivers, wetlands, lakes, reservoirs, rainfall intercepted by the canopy), surface ice and snow (glaciers, ice caps, grounded ice sheets, river and lake ice and other surface ice such as frozen flood water, snow lying on the surface and intercepted by the canopy) and subsurface water (liquid and frozen soil water, groundwater).'
Okay?
> 1.8 CMIP6 short name dtesn. Change in snow/ice cold content (CliC)
> "thermal_energy_content_of_surface_snow" exists, we can extend with "_and_ice".
>
> The ice includes all the ice above ground, including glaciers, ice sheets and floating ice shelves.
>
> + Propose:
> + change_over_time_in_thermal_energy_content_of_surface_snow_and_ice
> + (J m-2)
As for proposal 1.5 I am changing my suggestion to use the newly defined 'ice_and_snow_on_land':
change_over_time_in_thermal_energy_content_of_ice_and_snow_on_land (J m-2).
'The phrase "change_over_time_in_X" means change in a quantity X over a time-interval, which should be defined by the bounds of the time coordinate. The surface called "surface" means the lower boundary of the atmosphere. "Content" indicates a quantity per unit area. Thermal energy is the total vibrational energy, kinetic and potential, of all the molecules and atoms in a substance. The phrase "ice_and_snow_on_land" means ice in glaciers, ice caps, ice sheets & shelves, river and lake ice, any other ice on a land surface, such as frozen flood water, and snow lying on such ice or on the land surface.
Okay? As with 1.5, I'd like to double check that we should include floating ice shelves, because this seems to differ from Hyungjun's description.
> 2. Feature depths
>
> 2.1 CMIP6 short name dmlt. Depth to soil thaw (CliC) Depth from
> surface to the zero degree isotherm. Above this isotherm T > 0o, and below this line T < 0o.
>
> When the surface temperature is above 0K and there is frozen soil at
> some point beneath the surface, thawed_soil_depth is the distance from the surface to the first 0K isotherm. When there is no thawed soil layer, the parameter should be reported as missing.
>
> + Proposed: thawed_soil_depth
For this one I previously suggested:
depth_at_shallowest_isotherm_defined_by_soil_temperature (m)
'Depth is the vertical distance below the surface. A soil temperature profile may go through one or more local minima or maxima. The "depth at shallowest isotherm" is the depth of the occurrence closest to the soil surface of an isotherm of the temperature specified by a coordinate variable or scalar coordinate variable with standard name soil_temperature.'
We already have soil_temperature as a standard name. Following discussion (off list) with Martin, I think we also need to add a new area type of 'unfrozen_soil' because this quantity should only be reported where the soil at the surface is thawed.
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: CF-metadata <cf-metadata-bounces at cgd.ucar.edu> On Behalf Of Martin Juckes - UKRI STFC
Sent: 17 May 2018 16:50
To: cf-metadata at cgd.ucar.edu
Cc: Hyungjun Kim <hjkim at iis.u-tokyo.ac.jp>
Subject: [CF-metadata] Standard names for LS3MIP: 8 temporal changes + 1 feature depth
Dear All,
Following some discussion with Hyungjun, I'd like to propose the following new standard names to support the LS3MIP CMIP6 data request.
1. Changes over time
1.1 dcw Change in Interception Storage [kg m-2]
The standard name "canopy_water_amount" exists.
+ Propose: change_over_time_in_canopy_water_amount
1.2 dgw Change in Groundwater [kg m-2]
We do not currently have any terms specifically for groundwater, so this concept needs to be defined: the following is proposed: "Groundwater is the subsurface water in the saturated zone."
+ propose: change_over_time_in_groundwater_amount
1.3 drivw Change in River Storage [kg m-2]
There is no existing term for the amount of water in rivers, though there are several for the rate of flow. Such terms as exist make no explicit reference to the definition of the what is meant by river water, so a clarification note is proposed.
+ Propose: change_over_time_in_river_water_amount
+ "River water amount refers to the water in the fluvial system (stream and floodplain)".
1.4 dslw Change in soil moisture [kg m-2]
Relates to changes in quantity mass_content_of_water_in_soil
+ Propose: change_over_time_in_mass_content_of_water_in_soil
1.5 dsn Change in snow water equivalent (including snow and ice) [kg m-2]
The ice includes all the ice above ground, including glaciers, ice sheets and floating ice shelves.
+ Propose: change_over_time_in_surface_snow_and_ice_amount
1.6 dsw Change in Surface Water Storage [kg m-2]
Surface water storage is interpreted as terrestrial water storage, which has a recently discussed name land_water_amount.
+ Propose: change_over_time_in_land_water_amount
1.7 dtes Change in surface heat storage (excluding snow and ice) [J m-2]
Includes soil layers+canopy+any other except snow/ice.
+ Propose:
+ change_over_time_in_thermal_energy_content_of_vegetation_and_litter_an
+ d_soil
1.8 dtesn Change in snow/ice cold content [J m-2] (CliC)
"thermal_energy_content_of_surface_snow" exists, we can extend with "_and_ice".
The ice includes all the ice above ground, including glaciers, ice sheets and floating ice shelves.
+ Propose:
+ change_over_time_in_thermal_energy_content_of_surface_snow_and_ice
2. Feature depths
2.1 dmlt Depth to soil thaw [m] (CliC)
Depth from surface to the zero degree isotherm. Above this isotherm T > 0o, and below this line T < 0o.
When the surface temperature is above 0K and there is frozen soil at some point beneath the surface, thawed_soil_depth is the distance from the surface to the first 0K isotherm. When there is no thawed soil layer, the parameter should be reported as missing.
+ Proposed: thawed_soil_depth
regards,
Martin
------
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.
Received on Fri Jun 29 2018 - 03:16:51 BST
