Oral Presentation AMOS Annual Meeting and International Conference on Tropical Meteorology and Oceanography

Transported and local contributions to carbon monoxide in tropical north Australia (#12)

Rebecca R Buchholz 1 , David P Edwards 1 , Helen M Worden 1 , Louisa K Emmons 1 , Nicholas B Jones 2 , Clare Paton-Walsh 2 , Nicholas M Deutscher 2 , Voltaire A Velazco 2 , David W T Griffith 2
  1. Atmospheric Chemistry Observations & Modeling, National Center for Atmospheric Research, Boulder, CO, United States
  2. Centre for Atmospheric Chemistry, University of Wollongong, Wollongong, NSW, Australia

Darwin is ideally placed to sample atmospheric composition impacted by local episodic fires, as well as pollution transported from further afar such as from Indonesia or the Northern Hemisphere. We use complementary sensitivities from satellite and ground-based remote-sensing instruments to investigate the source influence on column carbon monoxide (CO) for more than 10 years at Darwin. Satellite-borne Measurements of Pollution in the Troposphere (MOPITT) and a ground-based solar FTIR instrument in the Total Carbon Column Observing Network (TCCON) are used to develop CO timeseries anomalies between 2005 and 2018. Anomalies are discussed in relation to pollution delivery pathways of local, regional and long-distance origin. The ground-based spectrometer data capture local-scale pollution events, and also record the long-range transported effect of biomass burning emissions, such as from Indonesia. While large-scale pollution events impact both instruments, only the satellite instrument can provide regional and global context. We contrast the impact of large Indonesian burning events of 2006 and 2015 on Darwin and the region. Contributions to CO variability are quantified using the Community Atmosphere Model with chemistry (CAM-chem) using tagged tracers to distinguish relative impact from different CO source regions and sectors. Modeling is also used to calculate the relative roles of emissions and meteorology. Finally, fire is a major driver of CO interannual variability in this region and the magnitude of fire emissions is connected to climate through water-availability driven fuel growth. We therefore investigate the links between climate and chemistry by using the climate modes: El NiƱo Southern Oscillation; the Indian Ocean Dipole; the Tropical Southern Atlantic; and the Southern Annular Mode, to describe CO variability at Darwin.