Re: [CF-metadata] CMIP5 carbon cycle standard names

Pierre Friedlingstein Wed, 29 Sep 2010 08:28:49 -0700

Fine for me.

Pierre


On 29/09/2010 13:08, alison.pamm...@stfc.ac.uk wrote:

Dear Pierre et al,

I have been checking through the definitions of the carbon cycle names
and I think the name
surface_upward_mass_flux_of_carbon_due_to_emission_from_natural_sources
should more properly be called
surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to_em
ission_from_natural_sources.  Any objections?

Best wishes,
Alison

------
Alison Pamment                          Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre    Fax: +44 1235 446314
Rutherford Appleton Laboratory          Email: alison.pamm...@stfc.ac.uk
Chilton, Didcot, OX11 0QX, U.K.

-----Original Message-----
From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-
boun...@cgd.ucar.edu] On Behalf Of alison.pamm...@stfc.ac.uk
Sent: 27 September 2010 13:13
To: cf-metadata@cgd.ucar.edu
Cc: p.friedlingst...@exeter.ac.uk; cameronsmi...@llnl.gov;
pierre.friedlingst...@lsce.ipsl.fr
Subject: Re: [CF-metadata] CMIP5 carbon cycle standard names

Dear Pierre, Philip and Robert,

I think Philip's last email pretty much sums up the position as I
understand it.  There are two standard names involved, one describing
carbon release from all anthropogenic emissions and another describing
carbon release from fossil fuels alone. The only question is whether
these two quantities should most appropriately be named as surface
fluxes or atmospheric tendencies. The other carbon cycle emissions
names
are unaffected by this discussion as they are clearly surface
quantities.

Pierre has explained that the anthropogenic/fossil fuel quantities do
both include emissions from airborne sources such as aircraft and
chimneys.  The former are certainly not surface emissions; we could
debate the latter. I think it would be misleading to label the
emissions
purely as surface fluxes and we should instead call them atmospheric
tendencies. This way we are not tying the emissions to any particular
vertical location. In fact, the definition of 'emission' in CF

standard

names is as follows: ' "Emission" means emission from a primary source
located anywhere within the atmosphere, including at the lower

boundary

(i.e. earth's surface),' so it explicitly copes with the case of
emissions aloft. Also, to answer Pierre's point regarding the meaning
of
tendency, in standard names it is defined as follows: '

"tendency_of_X"

means derivative of X with respect to time.'

I agree with Philip's point that it would be worth expanding the
definitions where appropriate to explain more fully the relationship
between surface upward fluxes and emissions into the atmosphere as a
whole. I suppose that a surface downward flux would be considered
equivalent to the contributions from various deposition processes.

I think this has been a useful discussion as it has helped to clarify
the definitions of the names as well as arriving at the most
appropriate
terminology.  I think we should stick with the names as originally
accepted:

tendency_of_atmosphere_mass_content_of_carbon_dioxide_expressed_as_carb

o
n_due_to_anthropogenic_emission; kg m-2 s-1

tendency_of_atmosphere_mass_content_of_carbon_dioxide_expressed_as_carb

o
n_due_to_emission_from_fossil_fuel_combustion; kg m-2 s-1.

Robert contacted me by email with some comments regarding the
consistency of the carbon cycle names:

Carbon_content
1. leaf_carbon_content; kg m-2
2. wood_carbon_content; kg m-2
3. root_carbon_content; kg m-2
4. carbon_content_of_miscellaneous_living_matter; kg m-2
5. wood_debris_carbon_content; kg m-2

1, 2. 3 and 5 have the structure "X_carbon_content", while 4 has the

structure "carbon_content_of_X".  Is there any particular reason for
not
giving>  4 the name:

4. miscellaneous_living_matter_carbon_content,
which would conform to the pattern?

I think it was Jonathan who suggested
carbon_content_of_miscellaneous_living_matter as an improvement on my
original proposal of miscellaneous_living_compartments_carbon_content.
However, I think that Robert is correct that we could take Jonathan's
wording and change the order without loss of clarity.  Does anyone
object to using miscellaneous_living_matter_carbon_content?

Fluxes of carbon
1.  surface_upward_flux_of_carbon_dioxide_expressed_as_carbon
         [_due_to_emission_from_fires_excluding_land_use_change]; kg

m-2 s-1 2.

         surface_upward_mass_flux_of_carbon
         [_due_to_natural_emission]; kg m-2 3.
         surface_upward_carbon_flux
         [_due_to_plant_respiration_for_biomass_growth]; kg m-2 s-1

(I

have bracketted [...] the part of the name which is not relevant to my

question.)

Is there any difference in meaning between these three syntactic

forms

for carbon flux?   It's not my field, but on the face of it they

appear

to be alternative way of expressing the same quantity.

I presume that there is a principle that, where possible, names

should
be constructed according to a consistent pattern (especially in the
light of>  Jonathan's work on rules for formulating names), so my

guess

is that there are some reasons for the above differences but I am not
sure

what they are.   As you've probably guessed, my interest in this

relates

to my own work on developing a grammar for standard names, and it is

clearly desirable to reduce the number of grammar rules to a minimum.

I agree that wherever possible we should stick to using a small set of
grammar rules.  However, there are occasions where being too rigid
about
the syntax can result in immensely long and unwieldy (and therefore
difficult to understand) names.  Often it is just a question of
readability.

I think we could call the second quantity

surface_upward_mass_flux_of_carbon[_due_to_emission_from_natural_source

s
]
to make it more consistent with the first without any loss of
readability.  Does anyone object to this change?

Looking at the third name and trying to squeeze it into the same
pattern
would give something like:

surface_upward_carbon_mass_flux_due_to_emission_from_plant_respiration_

f
or_biomass_growth
which I think is less readable, so I prefer the syntax without the
'emission'.  Do others agree?
(Incidentally, this would also affect another related name:

surface_upward_carbon_mass_flux_due_to_plant_respiration_for_biomass_ma

i
ntenance).

Robert's email has caused me to re-read the names more carefully and I
realise that I have neglected to make clear that many of the carbon
fluxes are in fact mass fluxes (as opposed to mole fluxes, for
example).
I would like to slightly revise some of the names already accepted to
include the word 'mass':

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to_e

m
ission_from_fires_excluding_land_use_change; kg m-2 s-1

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to_e

m
ission_from_grazing; kg m-2 s-1

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to_e

m
ission_from_crop_harvesting; kg m-2 s-1

surface_net_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_

t
o_emission_from_anthropogenic_land_use_change; kg m-2 s-1

surface_net_downward_mass_flux_of_carbon_dioxide_expressed_as_carbon_du

_to_photosynthesis_and_respiration_and_fires_including_land_use_change;

kg m-2 s-1
carbon_mass_flux_into_soil_from_litter; kg m-2 s-1
carbon_mass_flux_into_soil_from_vegetation_excluding_litter; kg m-2

s-1

surface_upward_carbon_mass_flux_due_to_plant_respiration_for_biomass_gr

o
wth; kg m-2 s-1

surface_upward_carbon_mass_flux_due_to_plant_respiration_for_biomass_ma

i
ntenance; kg m-2 s-1

surface_net_downward_mass_flux_of_carbon_dioxide_expressed_as_carbon_du

_to_photosynthesis_and_respiration_and_fires_excluding_land_use_change;

kg m-2 s-1.

Best wishes,
Alison

------
Alison Pamment                          Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre    Fax: +44 1235 446314
Rutherford Appleton Laboratory          Email:
alison.pamm...@stfc.ac.uk
Chilton, Didcot, OX11 0QX, U.K.

-----Original Message-----
From: Cameron-smith, Philip [mailto:cameronsmi...@llnl.gov]
Sent: 23 September 2010 19:48
To: Pierre Friedlingstein; Pamment, Alison (STFC,RAL,SSTD)
Cc: cf-metadata@cgd.ucar.edu
Subject: RE: [CF-metadata] CMIP5 carbon cycle standard names

Hi Pierre,

Sorry for causing confusion.

I understood that the question was whether to introduce the

following

two standard names (for your purpose)

tendency_of_atmosphere_mass_content_of_carbon_dioxide_expressed_as_carb

on_due_to_anthropogenic_emission; kg m-2 s-1

tendency_of_atmosphere_mass_content_of_carbon_dioxide_expressed_as_carb

on_due_to_emission_from_fossil_fuel_combustion; kg m-2 s-1

Or these two,

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to_a

nthropogenic_emission; kg m-2 s-1

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to_e

mission_from_fossil_fuel_combustion; kg m-2 s-1.

Alison had originally proposed the former (tendency_), and you

(Pierre)

argued for the latter (surface_).

What I liked was Alison's description of why these tendency_ and
surface_ quantities are physically different because the tendency_
quantity also includes non-surface emissions.

My first point was that your application included aircraft emissions

so

that the tendency_ quantity is the correct physical quantity for

your

application (even if your data may put the aircraft emissions in the
wrong box).  Hence, I recommended we add the tendency_ names to the
standard name list, rather than the surface_ names (following CF
tradition of not adding names unless needed).

My second point was that we already have both tendency_ and surface_
names in the list, and many users could easily miss the physical
distinction.  Hence, I suggested that we expand the descriptions of
these names in the list (when they occur) to highlight the

distinction

(because, as you say, many people are likely to look for the

surface_

names).

My third point was just to note that the one example of a standard

name

similar to the surface_ names proposed above actually specifies the
_downward_ direction.

I am somewhat sensitive to this issue because I am currently trying

to

use various emission estimates and it is often hard to tell what is

and

isn't included, and hence whether or not I am double counting.

Best wishes :-),

      Philip

-----------------------------------------------------------------------

Dr Philip Cameron-Smith, p...@llnl.gov, Lawrence Livermore National

Lab.

-----------------------------------------------------------------------

-----Original Message-----
From: Pierre Friedlingstein [mailto:p.friedlingst...@exeter.ac.uk]
Sent: Thursday, September 23, 2010 10:50 AM
To: Cameron-smith, Philip; alison.pamm...@stfc.ac.uk
Cc: cf-metadata@cgd.ucar.edu
Subject: Re: [CF-metadata] CMIP5 carbon cycle standard names

Hi all,
I'm getting confused now.
I understood Alison last proposal as keeping only one name :

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to_a

nthropogenic_emission; kg m-2 s-1

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to_e

mission_from_fossil_fuel_combustion; kg m-2 s-1.

   Philip's mail, seemed to imply that both names could be used as

he

liked Alison's distinction...

Could you clarify what the final decision?

For info, yes the data do include aircraft, chimneys,... emissions

as

these data are derived from country based reporting of fossil fuel
trades.
Hence the aircraft emissions from US carriers are in the US

numbers

and

hence assigned on the US territory.  This might be OK for US as

most

of

the flight are domestic, but I'm sure this is 99.9 % wrong for

Belgium

;-).
Saying emissions are a vertical integral here would imply that

planes

are only flying up and down !

Anyway, I will leave with either or definition (you'll just have

to

explain what the "tendency" one mean to non-chemists...)

Best
Pierre



On 22/09/2010 17:28, Cameron-smith, Philip wrote:

Hi All,

Even if the dataset doesn't have vertical information, if it

includes

aircraft emissions then the physical quantity it is quantifying

is

the

vertical integral rather than the surface emission.  In which

case

would favour tendency_of_atmosphere_mass_content_

If there are no aircraft in the data, then do smoke stacks

produce

'surface emissions'?  An interesting question that could be

debated.

Hence, another advantage of tendency_of_atmosphere_mass_content_

is

that it makes the question moot.

BTW, FWIW, I note that the closest related standard name already

in

the table specifies the downward direction

(surface_downward_mass_flux_of_carbon_dioxide_expressed_as_carbon).

On a different note, I like Alison's distinction between

tendency_of_atmosphere_mass_content_of_..._due_to_anthropogenic_emissi

on

and

surface_upward_mass_flux_of_..._due_to_anthropogenic_emission

Perhaps we should cross-reference such standard names in their

descriptions to help future users?

Best wishes,

       Philip

-------------------------------------------------------------------

--

-- Dr Philip Cameron-Smith,  p...@llnl.gov,  Lawrence Livermore

Nat.

Lab.

-------------------------------------------------------------------

--

--

-----Original Message-----
From: cf-metadata-boun...@cgd.ucar.edu [mailto:cf-metadata-
boun...@cgd.ucar.edu] On Behalf Of Pierre Friedlingstein
Sent: Wednesday, September 22, 2010 6:01 AM
To: alison.pamm...@stfc.ac.uk
Cc: cf-metadata@cgd.ucar.edu
Subject: Re: [CF-metadata] CMIP5 carbon cycle standard names

Alison,
I see your point.
As far as I know the anthropogenic emissions data will be

surface

fluxes. Data are based on country level consumption of fossil

fuel,

they don't have the info on where in the air it is released...
Pierre

      On 22/09/2010 13:04, alison.pamm...@stfc.ac.uk wrote:

Hi Pierre,

My thinking here was that 'anthropegenic emissions' (which
presumably include fossil fuel emissions) and 'fossil fuel'
emissions themselves do not necessarily always occur at the

earth's

surface.  For example, emissions from tall chimneys and

aircraft

may

occur at many levels in the atmosphere.  It was not clear to

me

that

these particular quantities in the CMIP5 tables are intended

only

to

account for

surface emissions.

If that is the case, then we certainly need to make it clear

and

agree with your suggestion to label them as surface fluxes. So

instead

of introducing

tendency_of_atmosphere_mass_content_of_carbon_dioxide_expressed_as_ca

bo n_due_to_anthropogenic_emission; kg m-2 s-1

tendency_of_atmosphere_mass_content_of_carbon_dioxide_expressed_as_ca

bo n_due_to_emission_from_fossil_fuel_combustion; kg m-2 s-1

I will add

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to

an
thropogenic_emission; kg m-2 s-1

surface_upward_mass_flux_of_carbon_dioxide_expressed_as_carbon_due_to

em ission_from_fossil_fuel_combustion; kg m-2 s-1.

OK?

Best wishes,
Alison

------
Alison Pamment                          Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre    Fax: +44 1235 446314
Rutherford Appleton Laboratory          Email:

alison.pamm...@stfc.ac.uk

Chilton, Didcot, OX11 0QX, U.K.

-----Original Message-----
From: Pierre Friedlingstein

[mailto:p.friedlingst...@exeter.ac.uk]

Sent: 21 September 2010 16:41
To: Pamment, Alison (STFC,RAL,SSTD)
Cc: j.m.greg...@reading.ac.uk; cf-metadata@cgd.ucar.edu
Subject: Re: [CF-metadata] CMIP5 carbon cycle standard names

Hi Alison,
Just wondering, why are the first two variables below named

as

"tendency_of_atmosphere_mass_content_of..."
while all others are named as  "surface_upward_mass_flux_of_

..."

Any reason ?
I know the "tendency..." is used for other chemical

species...

But

here

for CO2 variables, I think intra-consistency should be

favoured.

No

Best
Pierre

On 21/09/2010 13:40, alison.pamm...@stfc.ac.uk wrote:

Dear Jonathan and Pierre,

Thank you both for your comments on the CMIP5 carbon cycle

names.

Looking back through this thread I think we have resolved

all

the

outstanding issues and so the following names are now

accepted

for

inclusion in the standard name table:

tendency_of_atmosphere_mass_content_of_carbon_dioxide_expressed_as_ca

bo n_due_to_anthropogenic_emission; kg m-2 s-1

tendency_of_atmosphere_mass_content_of_carbon_dioxide_expressed_as_ca

bo n_due_to_emission_from_fossil_fuel_combustion; kg m-2 s-1
surface_upward_mass_flux_of_carbon_due_to_natural_emission;

     kg m-

s-1
atmosphere_mass_of_carbon_dioxide; kg
carbon_content_of_products_of_land_use_change; kg m-2

surface_upward_flux_of_carbon_dioxide_expressed_as_carbon_due_to_emis

io n_from_fires_excluding_land_use_change; kg m-2 s-1

surface_upward_flux_of_carbon_dioxide_expressed_as_carbon_due_to_emis

io
n_from_grazing; kg m-2 s-1

surface_upward_flux_of_carbon_dioxide_expressed_as_carbon_due_to_emis

io
n_from_crop_harvesting; kg m-2 s-1

surface_net_upward_flux_of_carbon_dioxide_expressed_as_carbon_due_to_

mi ssion_from_anthropogenic_land_use_change; kg m-2 s-1

surface_net_downward_flux_of_carbon_dioxide_expressed_as_carbon_due_t

_p

hotosynthesis_and_respiration_and_fires_including_land_use_change;

kg
m-2 s-1
carbon_flux_into_soil_from_litter; kg m-2 s-1
carbon_flux_into_soil_from_vegetation_excluding_litter; kg

m-

s-

leaf_carbon_content; kg m-2 wood_carbon_content; kg m-2
root_carbon_content; kg m-2
carbon_content_of_miscellaneous_living_matter; kg m-2 (N.B.
'miscellaneous' means carbon content of living matter apart

from

those

individually named in the preceding three items)
wood_debris_carbon_content; kg m-2

surface_litter_carbon_content;

kg

m-2 subsurface_litter_carbon_content; kg m-2
fast_soil_pool_carbon_content; kg m-2

medium_soil_pool_carbon_content;

kg m-2 slow_soil_pool_carbon_content; kg m-2

surface_upward_carbon_flux_due_to_plant_respiration_for_biomass_growt

;
kg m-2 s-1

surface_upward_carbon_flux_due_to_plant_respiration_for_biomass_maint

na
nce; kg m-2 s-1
net_primary_productivity_of_carbon_accumulated_in_leaves; kg

m-

s-

net_primary_productivity_of_carbon_accumulated_in_wood; kg

m-

s-

net_primary_productivity_of_carbon_accumulated_in_roots; kg

m-2

s-1

surface_net_downward_flux_of_carbon_dioxide_expressed_as_carbon_due_t

_p

hotosynthesis_and_respiration_and_fires_excluding_land_use_change;

kg
m-2 s-1.

To cope with the various fractional vegetation coverage

quantities

we

will use the existing standard name area_fraction and

introduce

new entries of primary_evergreen_trees,

secondary_deciduous_trees,

secondary_evergreen_trees, C3_plant_functional_types,
C4_plant_functional_types into the area_type table.

Best wishes,
Alison

------
Alison Pamment                          Tel: +44 1235 778065
NCAS/British Atmospheric Data Centre    Fax: +44 1235 446314
Rutherford Appleton Laboratory          Email:

alison.pamm...@stfc.ac.uk

Chilton, Didcot, OX11 0QX, U.K.

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