An example of downwind methane plume measurement. A Google Earth representation of an example of methane mixing ratios (red bars) measured by the GSV car along its pass around the ammonia fertilizer plant located in Fort Dodge, IA. Small methane spikes, which may be caused by unground pipeline leaks and not related to emissions from the fertilizer plant, are identified as local emissions. DOI: https://doi.org/10.1525/elementa.358.f2