| dc.description.abstract | Greenhouse gases methane (CH4), and carbon dioxide (CO2), along with carbon monoxide (CO), while produced by both anthropogenic and natural sources, all contribute to atmospheric warming. Additionally, CO poses health risks to individuals. If the atmospheric dynamics in a region are understood, it should be possible to use regional-scale sensors to evaluate emissions from upwind sources with respect to atmospheric variability.
The GeoCarb-TRACER Campaign was designed to observe these trace gases and their dynamics as a part of the TRacking Aerosol Convection interactions ExpeRiment (TRACER), organized by the U.S. Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) user facility in Houston, TX. During this campaign, portable Bruker EM27/SUN Fourier transform spectrometers were deployed at various urban and background sites in the summer of 2022. Each EM27/SUN captures high-resolution (0.5 cm-1) spectra in the near- and shortwave-infrared wavelength range. Multiple EM27/SUN spectrometers were deployed simultaneously alongside instruments gathering boundary layer, aerosol, and near-surface meteorological information. Spectra were analyzed to retrieve column-averaged concentrations of CO2, CO, and CH4, in reference to water vapor in the atmosphere. Researchers used unsupervised machine learning techniques to identify relationships between heightened EM27/SUN concentration measurements and local meteorological and anthropogenic source information. Targeting certain conditions for in-depth case studies identified by the machine learning analysis of local emission sources and co-emitted pollutants will inform further study. This cluster analysis approach highlights potential relationships between heightened EM27/SUN concentrations, surface meteorological conditions, and local industrial sources that may have been overlooked with a daily case study analysis.
Each EM27/SUN instrument was validated by intra- and inter-device comparison using a higher-resolution spectrometer from the TCCON (Total Carbon Column Observing Network) corrected to World Meteorological Organization (WMO) standards to ensure data accuracy, demonstrating minimal bias between instruments using the GGG2020 retrieval algorithm to process raw data. Empirical modifications to the retrieval algorithm were implemented to further correct the EM27/SUN data for solar zenith angle dependence and bring the retrieved concentration data up to the WMO standard, ultimately providing the most accurate representation of the data when compared to TCCON. Additionally, a series of automated data quality filters were developed to remove erroneous data during loss of tracking episodes. EM27/SUN TRACER data also validated the Orbiting Carbon Observatories, OCO-2 and OCO-3, indicating the bias between the EM27/SUN instruments and satellites were small, supporting the assertion that the OCO instruments provide an accurate representation of CO2 concentrations in the atmosphere even in proximity to urban and industrial pollutant sources. | en_US |
