High Accuracy Trace Gas Measurements from a Lightweight UAV

Article/Figure Provided By: Colm Sweeney and Pieter Tans

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Recently, numerous studies have contested the global impact of fugitive emissions from oil and gas operations on the methane budget.  Consequently, precise quantification of gas leaks is needed to better constrain the total methane burden from this source.  In the past, high precision insitu analyzers mounted in a research aircraft have been used to circle the suspected leak and quantify the plume.  While this is a robust method, it is costly, and missions cannot be deployed quickly.  Quick deployment is needed because leaks can be transient, variable, and a huge safety hazard.  A lightweight UAV is uniquely suited to both fly through a plume generated by a leak, and deploy quickly at little cost. However, the UAV platform is too small to carry the 70-pound analysis system used on a plane.

NOAA GMD has developed a unique sampling system, called the Active AirCore, in which a pump compresses air into a 100-meter long, small diameter tube at a constant flow rate. This long tube acts as an “atmospheric tape recorder” by storing the sample stream in the long tube. When the sample is analyzed, the data is a “play back” of the air the UAV flew through while in flight.  The sampler can be removed from the UAV, and immediately analyzed using an ultra-high precision trace gas analyzer like those used on aircraft.  This new sampling system provides the same level of accuracy as an analyzer mounted on a larger aircraft, but is light enough to be flown on a UAV.  Because the measurements are done in a van at the flight location, data analysis and quantification of the leak is near-real time.  This near-real-time analysis allows highly flammable natural gas leaks to be quickly identified and quantified providing information that will help evaluate the safety and potential economic losses at an individual oil and gas production site.

Nighttime Fire Observations eXperiment (NightFOX)


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Biomass burning produces major impacts on local and regional air quality which potentially plays an interactive role in climate change. A capable small, fixed-wing unmanned aircraft system (sUAS) can serve as an ideal platform for measurements of biomass burning emissions, plume distribution, fire extent and perimeter, and supporting meteorological data, especially at night when manned aircraft typically do not operate. The NOAA UASPO-funded Nighttime Fire Observations eXperiment (NightFOX) project aims to develop and deploy a sUAS observation system utilizing two modular and easily exchangeable payloads. One payload will provide in situ measurements of CO2, CO and fine- and coarse-mode aerosol size distributions in biomass burning plumes for characterization of fire combustion efficiency and emissions. A filter sampler will collect bulk aerosol samples for off-line composition analysis. The second payload will be flown over the fire to make remote sensing measurements of fire perimeter and fire radiative power using visible and short-, mid-, and long-wavelength IR observations. The multi-spectral remote sensing data will be used to provide sub-pixel information for comparison with satellite fire observations, and along with measured meteorological parameters, will be used to inform, test, and improve the WRF-SFIRE fire-atmosphere model.

Prototype in-situ and remote-sensing instrument payloads have been developed and are operational. Initial test flights with the payloads have recently been conducted. The performance of the prototype payloads has proven satisfactory and new versions are currently under development that will be used for the NIghtFOX operational deployment to study western wildfires next summer during the NOAA/NASA FIREX-AQ mission. Preliminary data processing algorithms for the remote sensing observations have been developed based on test flight results. A nighttime high-altitude FAA COA was obtained and a nighttime flight to an altitude of 2000 ft (0.61 km) was conducted on November 08, 2018, as a stepping stone to the 1 km design altitude for remote sensing operations.