Standard names: additional wildland fire indexes

[akessenich]

This is an addendum to names proposed in issue cf-convention/vocabularies#142. This work is related to the NA-CORDEX archive and supported by NSF Growing Convergence Research.

Proposer's name: Lee Kessenich, National Center for Atmospheric Research

Date: April 18, 2024

- Term: nfdrs_1_hour_fuel_moisture_content - Description: 1 hour fuel moisture (FM1) represents the modeled moisture content of dead fuels consisting of herbaceous plants or roundwood less than one-quarter inch in diameter. It also includes the uppermost layer of litter on the forest floor. The 1-hour timelag fuel moisture is a function of length of day (as influenced by latitude and calendar date), daily downwelling shortwave radiation, daily maximum temperature and minimum relative humidity, and daily precipitation values. It is a component in the US National Fire Danger Rating System. The US National Fire Danger Rating System comprises several numeric indexes that rate the potential over a large area for wildland fires to ignite, spread, and require action to suppress or manage. It was designed for use in the continental United States, and all its components are relative, not absolute. *adapted from Gaining a Basic Understanding of NFDRS - Units: %

- Term: nfdrs_10_hour_fuel_moisture_content - Description: 10 hour fuel moisture (FM10) represents the modeled moisture content of dead fuels consisting of roundwood in the size range of one quarter to 1 inch in diameter and very roughly, the layer of litter extending from just below the surface to three-quarters of inch below the surface. The 10-hour timelag fuel moisture is a function of length of day (as influenced by latitude and calendar date), daily downwelling shortwave radiation, daily maximum temperature and minimum relative humidity, and daily precipitation values. It is a component in the US National Fire Danger Rating System. The US National Fire Danger Rating System comprises several numeric indexes that rate the potential over a large area for wildland fires to ignite, spread, and require action to suppress or manage. It was designed for use in the continental United States, and all its components are relative, not absolute. *adapted from Gaining a Basic Understanding of NFDRS - Units: %

- Term: hot_dry_windy_index - Description: The Hot-Dry-Windy Index is the product of windspeed and vapor pressure deficit. It is a fire weather index that indicates the influence that the atmosphere has on a fire through wind, heat, and moisture. Its units are largely meant to be ignored. - Units: hPa m s-1

[github-actions[bot]]

Thank you for your proposal. These terms will be added to the cfeditor (http://cfeditor.ceda.ac.uk/proposals/1) shortly. Your proposal will then be reviewed and commented on by the community and Standard Names moderator.

[JonathanGregory]

Dear Lee @akessenich

Thanks for your proposal. For consistency with what was agreed in https://github.com/cf-convention/vocabularies/issues/142, the first two of these should be

nfdrs_1_hour_fuel_moisture nfdrs_10_hour_fuel_moisture

As for the "hot dry windy index", I feel that since it can be written in a non-jargon CF-like way, that would be preferable. According to your definition, we would call it product_of_wind_speed_and_water_vapor_saturation_deficit_in_air, since both wind_speed and water_vapor_saturation_deficit_in_air are existing standard names. The canonical unit would be Pa m s-1. Would this be acceptable, if we put in the description words to the effect that this quantity, when expressed in hPa m s-1, is called the "hot dry windy index" in the US National Fire Danger Rating System?

Best wishes

Jonathan

[akessenich]

Hi Jonathan,

Thank you for your feedback. I agree on changing nfdrs_1_hour_fuel_moisture nfdrs_10_hour_fuel_moisture to match the others-- that was an error on my end, I meant to have them match the accepted names already.

For the hot dry windy index, it should be clarified that the index is unrelated to the US National Fire Danger Rating System. To match with the conventions of standard names, I propose the following for the hot dry windy index:

• Term: product_of_wind_speed_and_water_vapor_saturation_deficit_in_air
• Description: The product of windspeed and vapor pressure deficit is referred to as the Hot-Dry-Windy Index for interpreting fire weather. It is a fire weather index that indicates the influence that the atmosphere has on a fire through wind, heat, and moisture. Its units are largely meant to be ignored in its interpretation, but for consistency, units of hPa m s-1 are used.
• Units: Pa m s-1

Thanks, Lee

[JonathanGregory]

Dear Lee

Thanks for clarifying about the US National Fire Danger Rating System. I think this description is fine, except for "Its units are largely meant to be ignored in its interpretation". That's true if you regard it as an index, but not if it's a dimensional geophysical quantity. Instead of that last sentence "Its units ...", would it be correct to say, "As a fire weather index, it should be expressed in hPa m s-1, because these units are expected and usually not stated." Is that the situation, as I guess?

Best wishes

Jonathan

[efisher008]

Dear Lee @akessenich,

I have added your proposed names to the CF editor, and you can view their current status at the links below:

• nfdrs_1_hour_fuel_moisture (originally nfdrs_1_hour_fuel_moisture_content): here
• nfdrs_10_hour_fuel_moisture (originally nfdrs_10_hour_fuel_moisture_content): here
• product_of_wind_speed_and_water_vapor_saturation_deficit_in_air (originally hot_dry_windy_index): here

I have only made agreed changes to the entries up to your last post, excluding for the moment @JonathanGregory's suggestion.

Looking forward to more discussion on this.

Best regards, Ellie

[akessenich]

Hi Jonathan,

Thanks for your suggestion, it is very close to what needs to be communicated. I've included a sentence from the paper that developed HDW that is hopefully precise:

- Term: product_of_wind_speed_and_water_vapor_saturation_deficit_in_air - Description: The product of windspeed and vapor pressure deficit is referred to as the Hot-Dry-Windy Index (HDW) for interpreting fire weather. It is a fire weather index that indicates the influence that the atmosphere has on a fire through wind, heat, and moisture. The units of HDW do not have an established physical significance for fire processes. As a fire weather index, it should be expressed in units of hPa m s-1. - Units: Pa m s-1

Also thanks to Ellie for adding the proposed names to the CF editor.

-- Lee

[JonathanGregory]

That's great. Thanks, Lee.

[efisher008]

Hello Lee @akessenich,

I have made the change to the description for product_of_wind_speed_and_water_vapor_saturation_deficit_in_air. Just to clarify, are the acronyms FM1 and FM10 for the fuel moisture names "imported" from the NFDRS term-base?

Best wishes, Ellie

[akessenich]

Hi Ellie, For FM1 and FM10, there doesn't seem to be an official acronym. FM is a very frequently used abbreviation for fuel moisture in official literature. FM1 and FM10, as well as the previously added FM100 and FM1000, are common abbreviations for those fuel moisture content classes. For example, this paper and the gridMET archive. Should the acronym be omitted for the description? Thanks, Lee

[efisher008]

Hi Lee @akessenich,

Thank you for the references, the abbreviations are also self-explanatory so I don't think these require any further clarifying in the description and they do not need to be removed. Could the paper you reference (Carlson et al. 2007) be included at the end of the description, or is there different literature you think would be more useful here?

Best, Ellie

[akessenich]

Hi Ellie,

Which literature should be included at the end depends on its purpose-- is it to show the acronym is used, or a more generic reference overall? Carlson et al. 2007 was just an example of the acronym, there are more direct documentation for FM1 and FM10 in fire index literature.

Thanks, Lee

[akessenich]

This discussion regarding this post dropped off about 3 weeks ago. Is there anything further that I can do to support these terms being added?

Thanks, Lee

[efisher008]

Hi Lee,

In answer to your earlier question, I think a more generic reference for FM1 and FM10 might be more useful in this case. The original issue cf-convention/vocabularies#142 does not contain any paper reference, but I think these new names should have one if possible. Do you have documentation in mind?

Best wishes, Ellie

[akessenich]

Thanks, Ellie. I think that this document, "Gaining a Basic Understanding of the National Fire Danger Rating System" page 27 is well suited for this purpose. --Lee

[efisher008]

Hello Lee,

Thank you for the reference. I agree that this is suitable and have added this as a link to the proposal in the CF editor. You can view the terms here:

product_of_wind_speed_and_water_vapor_saturation_deficit_in_air nfdrs_10_hour_fuel_moisture nfdrs_1_hour_fuel_moisture

As there seems to be general agreement in this issue, these names will be therefore accepted in 7 days if there are no further comments or issues. After this they will be added to the CF standard names table in the next update (v86).

Best, Ellie

[efisher008]

Hello Lee @akessenich,

Some time has passed and these names have now been accepted in the CF editor. They will be published in the next release of the standard names table (anticipated for summer 2024). Thank you again for your proposal!

Best regards, Ellie

[efisher008]

This has been published in v86 of the Standard Names Table (released 5 September 2024).