Temporal Allocation of Residential Fuel Combustion for 2019?


I have two questions about the residential and commercial/institutional fuel combustion emissions in the 2019 EQUATES platform.

(1) How are residential and commercial/institutional fuel combustion emissions temporally allocated? Is a constant fraction of the annual emissions total allocated to each hour of the year? I have found information about the spatial allocation regarding activity data, census information, etc., but nothing about the temporal allocation. I know that the final nonpt emissions have a representative weekday for each month (plus holidays) and a diurnal cycle, but I would like to know how that traces back to fuel combustion specifically.

(2) This page has a note that “The EQUATES base year emissions are from the 2017 NEI. For each sector in the 2017 NEI one of four approaches was applied to estimate emissions for the entire 2002-2019 time period: (1) Develop new methods for creating consistent emissions for all years (2) Use 2016 or 2017 model platform emissions and create scaling factors based on activity data and/or emission control information (3) Use existing modeling platform data for earlier years (2002-2015) (4) Leave emissions flat at 2017 NEI levels.” Which methods were used for the residential and commercial/institutional fuel consumption emissions in the 2019 platform?

Thank you for your help!

Cara Scalpone

Where I said “this page,” I was referring to the 2019 EQUATE platform data warehouse at this link: EQUATESv1.0: Emissions, WRF/MCIP, CMAQv5.3.2 Data -- 2002-2019 US_12km and NHEMI_108km - CMAS Data Warehouse

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Thank you for your interest in the EQUATES data. I reached out to one of the emissions experts from the EQUATES team, @james.beidler, who was able to provide this information on the temporal allocation:
The nonpt sector fuel combustion sources are temporally allocated based on the source category code (SCC) using three distinct annual-to-month profiles, two week-to-day, and a single diurnal profile. The same profiles were applied across all fuel types within the general industrial, commercial/institutional, and residential fuel combustion source classifications.

Residential and commercial fuel combustion sources had more emissions allocated to the winter and fall months than the summer. Industrial sources receive a flat monthly allocation.
Commercial and industrial emissions had a greater weekday then weekend allocation. Residential combustion source emissions are allocated evenly to each day of the week.
All fuel combustion sources in the nonpt sector get the same diurnal profile with emissions allocated mostly between 8am and 10pm, peaking around 2pm.

In terms of your second question, EQUATES 2019 residential and commercial/institutional fuel consumption emissions were based on the EPA’s 2019 Emissions Modeling Platform. The 2019 Platform Technical Support Document indicates that “The 2019 platform nonpt sector inventory is mostly unchanged from the January 2021 version of the 2017 NEI.” (Documentation for 2017 NEI.)

Another resource for the emissions processing for the EQUATES project is available in this paper, Foley et al., 2023. The methods are described for 2002-2017 (the original timeseries) but also apply for the 2019 emissions, except for some small differences in methods in a few sectors.