A253-10
Towards Global Emission Fluxes from Wildfires: An Error Assessment of Aerosol Optical Properties on Inert and Reactive Trace Gas Retrievals in Optically Thick Plumes
Thursday, 17 December 2020: 06:06
Virtual
Jake Rowe1, Kyle J Zarzana1, Natalie Kille2, Theodore Konstantinos Koenig1, Christopher F Lee1, Johana Romero Alvarez3, Christoph Knote4, Nicolas Theys5, Christophe Lerot5, Isabelle De Smedt5, Michel Van Roozendael5 and Rainer M Volkamer6, (1)University of Colorado Boulder, Chemistry & CIRES, Boulder, CO, United States, (2)University of Colorado Boulder, Atmospheric and Oceanic Sciences & CIRES, Boulder, CO, United States, (3)University of Colorado Boulder, Chemistry & CIRES, Boulder, United States, (4)Ludwig-Maximilians-University (LMU), Meteorological Institute, Munich, Germany, (5)Royal Belgian Institute for Space Aeronomy, Brussels, Belgium, (6)University of Colorado Boulder, Chemistry, ATOC & CIRES, Boulder, CO, United States
Abstract:
The Biomass Burning Fluxes of Trace Gases and Aerosols (BB-FLUX) field campaign was carried out during the summer of 2018 with the primary goal of quantifying emission fluxes of trace gases by mass balance of wildfires. To characterize these fluxes, the University of Colorado Airborne Solar Occultation Flux (CU AirSOF) instrument was flown below biomass burning plumes to measure vertical trace gas columns, such as CO, along the direct solar beam at mid-infrared wavelengths. These novel methods have recently been demonstrated during BB-FLUX for individual wildfires; however, the extension to satellites holds some largely unexplored promise and would enable global emission flux characterizations. The Sentinel-5 Precursor satellite, which houses the TROPOspheric Monitoring Instrument (TROPOMI), provides a unique opportunity to quantify and validate emission fluxes from space. Through daily observations of area sources such as wildfires, TROPOMI provides measurements of trace-gas maps in the UV-Vis (e.g. NO
2, HCHO, CHOCHO, and HONO) and shortwave-IR (SWIR) spectral regimes (e.g. CO, using the first overtone vibrational band).
The challenge with using TROPOMI here is in order to derive vertical trace gas columns, the radiative transfer in optically thick wildfire plumes must be characterized. Air mass factors (AMF) are a way to quantify the average photon path distribution and are widely used to convert satellite slant column measurements into vertical columns. CU AirSOF provides measurements of AMFs by observing HCHO simultaneously in scattered light and direct sun geometries below TROPOMI. In the SWIR, TROPOMI measures CO using backscattered solar photons, reducing aerosol effects for CO over the UV-vis gases. We explore this potential to further characterize radiative transfer in strong wildfire plumes using aircraft AMF measurements and radiative transfer simulations across the UV-vis and SWIR spectral range. Additionally, we use the FLEXible PARTicle Dispersion model to explore the ability to bridge different temporal and spatial sampling scales, and to differentiate background CO from biomass burning plumes upwind. Finally, the divergence flux approach is used to compare aircraft-derived mass fluxes with that extracted from stationary 2D satellite images, and the overall error budget is examined.
