CEDS Sector Mapping: 7BC_Indirect-N2O-non-agricultural

[jkikstra]

Question is: "What harmonization sector do we place '7BC_Indirect-N2O-non-agricultural' under?"

Steve (@ssmithClimate) commented on 21 Oct 2024:

"This is tricky, for ESMs with their own N-cycle would calculate this themselves. But others would need this.

We should probably put this into agriculture - if models have their own N cycle they would do all of that themselves, if they don't then they would want this.

ask the ESM groups - but I suspect few if any are doing endogenous N2O concentrations. But maybe a few?"

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I suggest that we follow Steve's suggestion, and update the sector_mapping for 7BC_Indirect-N2O-non-agricultural to Agriculture (currently it has no sector).

Later, we may also want to ask around:

• what IAM teams do for this; does it make sense for harmonization to put it under agriculture?
• how ESM teams view this

[jkikstra]

Note; this way we have 60 categories/sectors used from under the "59_Sectors_2024".

Only "6B_Other-not-in-total" is ignored.

[znichollscr]

ask the ESM groups - but I suspect few if any are doing endogenous N2O concentrations. But maybe a few?"

As far as I'm aware no N2O group does endogenous concentrations. (Some may do nitrogen cycle stuff, but they will be doing an inversion based on concentrations, which is different),

I'm assuming this source is small so whether we include it or not doesn't matter so much. Hence I would include it (I'm more confident that groups don't have this so it's better not to miss it than that we would inadvertently double count, although it does depend exactly what it is, do you have a full description/docs somewhere?)

[ssmithClimate]

Its in EDGAR as well (which is where we pull this from), which is the main other global dataset anyone would tend to use, so modelers have seen it before.

[znichollscr]

modelers

I assume you mean IAMs not ESMs here? Is it a small sector compared to the total (both global but also for agriculture)? Do you have a link to docs?

[ssmithClimate]

I was thinking ESMs.

[jkikstra]

Okay, can we conclude:

1. We include this.
2. We categorise it under "Agriculture" (relevant for how we will create the future grids with concordia)

[znichollscr]

Can you send me some docs on what 7BC actually is please

[jkikstra]

Can you send me some docs on what 7BC actually is please

Sorry, should have done more digging myself before and added that to the top; but this is what I could find.

This is IPCC2006 category 5.A.
Meaning (IPCC2006 docs):

• Name: Indirect N2O emissions from the atmospheric deposition of nitrogen in NOx and NH3
• Definition: Excluding indirect emissions from NOx and NH3 in agriculture which are reported in 3C5 & 3C6.

I confirmed this with the EDGAR N2O download that Steve says CEDS is pulled from.

I did not find anything in EDGAR-latest-publication or EDGAR-latest-report.
The name is all I have, unless we email someone from EDGAR or if Steve can explain more?

[ssmithClimate]

Yes, this is the definition:

• Name: Indirect N2O emissions from the atmospheric deposition of nitrogen in NOx and NH3
• Definition: Excluding indirect emissions from NOx and NH3 in agriculture which are reported in 3C5 & 3C6.

Its N2O emissions that occur as a result of deposition of anthropogenic reactive nitrogen in non-crop ecosystems. So its indirect anthropogenic N2O emissions.

[znicholls]

Ah ok. I'm pretty sure that's an input for all models I can think of (MAGICC plus ESMs), so yes please let's include that.

(As a note, what I don't know is how this should/does relate to the nitrogen deposition product that Michaela Hegglin will produce. Let's worry about that another day.)

[ssmithClimate]

Ah Gridding. We will make sure for the CMIP7 historical data treatment of 7BC_Indirect-N2O-non-agricultural-N is placed in AGR in our gridding.

[jkikstra]

OK; moved into Agriculture for our processing with #26 (link to #33)