Introducing a Low-Cost Approach for Environmental Monitoring with the Civil Air Patrol (CAP) Aircraft: An Example Addressing Greenhouse Gas Emissions

Abstract. Research aircraft provide essential information about weather, climate forcing, and air quality (AQ). Instrumenting and deploying these aircraft, however, requires substantial investment. Single engine Cessna aircraft flown by the Civil Air Patrol (CAP) offer practical, economical, and widely available platforms for tropospheric sounding of meteorological variables, greenhouse gases (GHGs), and short-lived pollutants. A recent partnership with CAP has led to frequent surveys across the state of Maryland with a Licor 7810 to measure CO2, CH4 , and H2O concentrations for GHG analyses and a basic meteorological measurement suite to investigate transport and calculate emission rates (ERs) using the mass balance approach (MBA). The flexibility of multiple aircraft and pilots facilitates surveys at weekly to bi-weekly timescales. This paper outlines the steps required for a successful operation with the CAP, including flight planning and procedures, instrument calibration, and post-processing. Flights dedicated to GHG sampling are used to demonstrate what the platform can deliver, while the approach itself is general and extends to other areas of environmental monitoring. Examples of CAP flights presented here highlight the strategic targeting of GHG emissions from sources selected through close coordination with the Maryland Department of the Environment (MDE), including frequent visits to landfills, natural gas facilities, and other sources to quantify short-term variability of ERs. Also highlighted are synergistic measurements characterizing GHG plumes from ground to flight level from CAP aircraft and NOAA's Air Resources Car (ARC) during a planned release at the Accident natural gas compressor station (NGCS). The documentation of frequent flights from this work and the availability of CAP aircraft in all 50 states demonstrates a scalable solution for frequent spatiotemporal GHG monitoring that addresses anthropogenic impacts, complements regional measurement efforts, and serves as a viable option for validating satellite retrievals.