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Comparison of Atmospheric Observations to High-resolution Fossil Fuel and Biogenic CO2 Flux Models for Auckland, New Zealand

T.W. Hilton1, E.D. Keller1, S. Karalliyadda1, A. Benson1, L. Domingues2, H. O'Sullivan-Moffat1,3, H. Young1,3, J. Parry-Thompson1, N. Turton1, L. Hutyra4, K. Gurney5 and J. Turnbull1,6

1GNS Science, National Isotope Centre, Lower Hutt, New Zealand; +64 04 570 4650 x8593, E-mail: t.hilton@gns.cri.nz
2Instituto de Pesquisas Energeticas e Nucleares (IPEN), São Paulo, Brazil
3Victoria University of Wellington, Wellington, New Zealand
4Boston University, Department of Earth & Environment, Boston, MA 02215
5Arizona State University, Tempe, AZ 85287
6NOAA Global Monitoring Laboratory (GML), Boulder, CO 80305

The largest city in New Zealand, Auckland is home to roughly 1.5 million people -- one third of New Zealand's population. Despite a large urban population, the city contains a significant amount of green space that can act as a carbon sink to offset anthropogenic fossil fuel emissions. Here we present a high resolution (street segments and buildings, hourly) bottom-up inventory of Auckland's fossil fuel carbon dioxide emissions from a variety of data sources. We are use these emissions estimates in combination with the UrbanVPRM land surface model to estimate the net carbon balance of the Auckland region. We compare this carbon balance estimate with atmospheric observations of CO2, CH4, CO, and 14CO2 collected from in situ sensors and flasks across the city as part of the CarbonWatch NZ project. CarbonWatch NZ uses atmospheric observations and modeling to assess New Zealand's progress toward its obligations under the Paris Agreement and New Zealand's Zero Carbon Act.

Figure 1

Figure 1. Mahuika AKL - a high resolution fossil fuel CO2 emission inventory for Auckland, New Zealand.

Figure 2

Figure 2. Flask and in situ sampling sites.