Mahuika‐Auckland: A spatially and temporally resolved fossil fuel CO₂ emissions data product for Auckland, New Zealand

Abstract

Accurate, high‐resolution and sector‐specific greenhouse gas emissions information is increasingly needed for the development of local, targeted mitigation policies. We describe a detailed, spatially and temporally resolved CO2 emissions data product, Mahuika‐Auckland, for Auckland, New Zealand, based on Auckland's regional greenhouse gas and air emissions inventories. Emissions are provided at 500 m spatial resolution and at a 1‐hr time step, a level of detail not previously available for any New Zealand city. We divide fossil fuel emissions into six sectors that comprise the majority of Auckland Region's CO2 emissions profile: on‐road transport, industrial non‐point buildings and point sources, commercial non‐point buildings, residential non‐point buildings, air transport and sea transport. We also include separate layers representing biogenic CO2 emissions (primarily waste and wood burning), as these are significant sources in Auckland. We distribute emissions spatially and temporally based on activity data, energy and fuel consumption patterns, and population statistics. The code to generate Mahuika‐Auckland has been designed to be flexible so that updated information and/or data from more recent years can easily be incorporated. This data product improves upon New Zealand's current inventories that are only resolved at the regional and annual scale, providing a new level of detail that can be used as a prior estimate for atmospheric inversions, to inform emissions reduction policies and to guide the development of zero carbon pathways.

Urban flask measurements of CO2ff and CO to identify emission sources at different site types in Auckland, New Zealand

“…Flow was restricted using a critical orifice to conserve sample air for subsequent analyses. To analyse 14 CO 2 in each sample, CO 2 was isolated from each sample using cryogenic extraction [46], graphitized [47] and analysed in the Extended Compact Accelerator Mass Spectrometry system in the Rafter Radiocarbon Laboratory at GNS Science [48]. Results are reported as 14 C [49].…”

“…CO 2 ff was calculated from the observed 14 C ( obs ), CO 2 mole fraction (CO 2 obs) and 14 C measured at the background site ( bg ) (equation 2.1) [21,50],…”

“…To analyse 14 CO 2 in each sample, CO 2 was isolated from each sample using cryogenic extraction [46], graphitized [47] and analysed in the Extended Compact Accelerator Mass Spectrometry system in the Rafter Radiocarbon Laboratory at GNS Science [48]. Results are reported as 14 C [49]. The 'excess' or enhancement in CO and CO 2 ff was determined for each sample, which was the added mole fraction as the air passed across Auckland City.…”

“…Recently, many cities have begun to inventory their emissions, often providing emission totals by sector [5][6][7][8][9]. The recent development of high-resolution emission maps for cities distribute CO 2 ff emissions spatially and temporally providing substantially more detailed information on urban emissions [4,[10][11][12][13][14][15][16][17]. However, it can be difficult to quantify uncertainties and recent research has demonstrated that uncertainties are larger for individual source sectors than for the totals [4,18].…”

“…Figure 2. CO, COxs,14 C and CO 2 ff observed for each of the site measurements. Sites are ordered by site name and site type (left to right on the x-axis: forest, industrial, suburban, downwind, urban and motorway).…”