Evaluating a UAV-based mobile sensing system designed to quantify ecosystem-based methane
Abstract
Methane plays an important role in determining the atmosphere's climate and chemistry. Fluxes of methane from an ecosystem are often measured using eddy covariance flux towers; however, there are disadvantages with this method. Flux towers are expensive to purchase and have high demands with respect to maintenance and cost of operation, especially in remote locations, making replication across the landscape a challenge. Using sensors mounted on a small unmanned aircraft system (sUAS), also known as a drone, would allow replication of flux measurements across a landscape as well as enable scientists to measure methane at locations where towers are not practical (i.e. sites that are ephemeral in nature, immediately after a disturbance, etc.). We have been testing the ability of a sUAS equipped with a highly accurate CH4 sensor to calculate flux using the mass balance method. This method uses data collected with curtains (transects at various heights) flown both upwind and downwind of the area of interest. The concentration of methane within these curtains is then estimated using kriging techniques. The difference in calculated amounts of methane between the upwind and downwind curtains is processed to obtain an estimate of flux. Flights in wetlands that also have eddy covariance towers, providing corroborating flux values, have been flown in both California and Alaska. We will compare flux calculations using the traditional mass balance technique to two other methods. The first calculates multiple flux estimations using decimated samples (i.e., subsampling and bootstrapping estimates) within the curtain data. The second method attempts to replace kriging with a machine learning approach. We will test if these different approaches improve the accuracy of our results, as well as the uncertainty bounds for the small fluxes emitted from these ecosystems.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA115.0007H
- Keywords:
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- 0368 Troposphere: constituent transport and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 0490 Trace gases;
- BIOGEOSCIENCES