CarbonWatch-NZ: A bird's eye view of New Zealand's CO2 and CH4 exchange in forests, grasslands, and urban environments.

Abstract:

Atmospheric observations of greenhouse gases have been widely used to constrain estimates of terrestrial and oceanic fluxes through atmospheric inverse modelling. Yet, applying these methods at national scale to verify and improve the National Inventory Report and support the Paris agreement remains at the frontier of greenhouse gas research. We present an overview of the newly funded CarbonWatch-NZ research programme, which will dramatically expand New Zealand's national scale CO₂ and CH₄ measurement and modelling research programme. This five year programme will expand New Zealand's national observing network to eleven permanent and four field deployable stations, introduce urban and regional forest scale studies, leverage measurements of isotopes and carbonyl sulphide to understand source and sink processes, and integrate flux tower observations to understand the role of pastures. State of the art land modelling, focused field studies, sub-national inverse modelling and partnerships with indigenous groups will allow a deeper understanding of forest carbon uptake and the impact of planting strategies and land management practices on our forest carbon sink. Data from over more than 30 site years of eddy covariance measurements will be combined with land modelling and atmospheric observations to study carbon cycling in New Zealand's grasslands. National scale CH₄ inverse modelling will inform NZ's emissions reporting and agricultural CH₄ mitigation strategy. An urban inverse model for New Zealand's largest city, Auckland, will shed new light on both emissions and the urban biosphere in this green subtropical city.In addition to our science strategy we will discuss the process used to engage New Zealand’s carbon accounting and environmental policy communities, starting from the development phase of the project. This will include the strategies used to resolve differences between components of the carbon budget counted in national reporting and those detected by the inversion, communicate uncertainties, and plan research activities that meet policy needs.