An aircraft-based data analysis method for discerning individual fluxes in a heterogeneous agricultural landscape

Kirby, Scott; Dobosy, R.; Williamson, Derek; Dumas, Edward J.

doi:10.1016/j.agrformet.2007.10.011

Cited by 26 publications

(26 citation statements)

References 35 publications

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“…Often such patches are too small for a traditional RFM (Kirby et al, 2008). The FFM, while based on the same statistical foundation as eddy covariance, uses a conditional sampling scheme whereby the flux, of methane for example, is compiled from many τ s "fragments" f i of methane fluxes along a transect, each given by…”

Section: Flux Fragment Methodsmentioning

confidence: 99%

“…The appropriate distance varies depending on boundary layer height, turbulence, and the footprint size of interest. Several groups have successfully measured carbon dioxide and heat flux from low-flying aircraft in the Arctic (Zulueta et al, 2011;Oechel et al, 2000Oechel et al, , 1998Gioli et al, 2004), Europe (Bange et al, 2007;Vellinga et al, 2010;Hutjes et al, 2010;Gioli et al, 2006), Asia (Metzger et al, 2013), and continental USA (Kirby et al, 2008;LeMone et al, 2003;Avissar et al, 2009). …”

Section: Introductionmentioning

confidence: 99%

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Arctic regional methane fluxes by ecotope as derived using eddy covariance from a low-flying aircraft

et al. 2017

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Abstract. The Arctic terrestrial and sub-sea permafrost region contains approximately 30 % of the global carbon stock, and therefore understanding Arctic methane emissions and how they might change with a changing climate is important for quantifying the global methane budget and understanding its growth in the atmosphere. Here we present measurements from a new in situ flux observation system designed for use on a small, low-flying aircraft that was deployed over the North Slope of Alaska during August 2013. The system combines a small methane instrument based on integrated cavity output spectroscopy (ICOS) with an air turbulence probe to calculate methane fluxes based on eddy covariance. We group surface fluxes by land class using a map based on LandSat Thematic Mapper (TM) data with 30 m resolution. We find that wet sedge areas dominate the methane fluxes with a mean flux of 2.1 µg m −2 s −1 during the first part of August. Methane emissions from the Sagavanirktok River have the second highest at almost 1 µg m −2 s −1 . During the second half of August, after soil temperatures had cooled by 7 • C, methane emissions fell to between 0 and 0.5 µg m −2 s −1 for all areas measured. We compare the aircraft measurements with an eddy covariance flux tower located in a wet sedge area and show that the two measurements agree quantitatively when the footprints of both overlap. However, fluxes from sedge vary at times by a factor of 2 or more even within a few kilometers of the tower demonstrating the importance of making regional measurements to map out methane emissions spatial heterogeneity. Aircraft measurements of surface flux can play an important role in bridging the gap between ground-based measurements and regional measurements from remote sensing instruments and models.

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Section: Flux Fragment Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Arctic regional methane fluxes by ecotope as derived using eddy covariance from a low-flying aircraft

et al. 2017

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“…Since the certification of the SDSU Sky Arrow, there have been numerous improvements and advancements in the electronics within the MFP (see, e.g., Hall et al 2006), including development of fast ultrasensitive temperature sensors (see, e.g., French et al 2001) not requiring the complex corrections described here, implementation of advanced integrated inertial measurement unit (IMU) and GPS (IMU-GPS) electronics (see, e.g., Garman et al 2006;Hall et al 2006;Vellinga et al 2010Vellinga et al , 2013, as well as more durable and robust BAT probes and pressure spheres (see, e.g., Eckman et al 2007;French et al 2004). New wind tunnel tests (Dobosy et al 2013;Garman et al 2006) and calibration techniques and procedures (Garman et al 2008(Garman et al , 2006Vellinga et al 2013) have improved the accuracy of wind vector calculations, while research into flux disaggregation methods Kirby et al 2008;Ogunjemiyo et al 2003) and surface flux mapping techniques (e.g., Mauder et al 2008) have improved associating surface fluxes to landscape elements in heterogeneous areas. Analysis strategies like the flightpath segmentation presented in Vellinga et al (2010) allow for regional-scale estimates of heterogeneous terrain from aircraft-based fluxes based on landscape characteristics.…”

Section: Rapidly Evolving Aircraft Technologiesmentioning

confidence: 99%

“…The flux footprint varies in size and depends on the measurement height above the surface, wind vector, surface roughness, and atmospheric stability (Leclerc and Thurtell 1990). Here, we used the footprint model of Kljun et al (2004), which is a parameterization of a Lagrangian stochastic footprint model (LPDM-B; Kljun et al 2002). The model described in Kljun et al (2004) is a crosswind integrated footprint model that allows for rapid calculations with input parameters easily derived from common turbulence measurements.…”

Section: G Flux Footprintsmentioning

confidence: 99%

“…To relate fluxes measured by tower and aircraft to their sink/source area on the ground, a footprint model was used to describe the contribution of the surface area to the measurement at a particular location (Kljun et al 2002(Kljun et al , 2004Leclerc and Thurtell 1990;Schmid 2002;Schuepp et al 1990). The flux footprint varies in size and depends on the measurement height above the surface, wind vector, surface roughness, and atmospheric stability (Leclerc and Thurtell 1990).…”

Section: G Flux Footprintsmentioning

confidence: 99%

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Aircraft Regional-Scale Flux Measurements over Complex Landscapes of Mangroves, Desert, and Marine Ecosystems of Magdalena Bay, Mexico

Zulueta

Oechel

Verfaillie

et al. 2013

Journal of Atmospheric and Oceanic Technology

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Natural ecosystems are rarely structurally simple or functionally homogeneous. This is true for the complex coastal region of Magdalena Bay, Baja California Sur, Mexico, where the spatial variability in ecosystem fluxes from the Pacific coastal ocean, eutrophic lagoon, mangroves, and desert were studied. The Sky Arrow 650TCN environmental research aircraft proved to be an effective tool in characterizing land-atmosphere fluxes of energy, CO 2 , and water vapor across a heterogeneous landscape at the scale of 1 km. The aircraft was capable of discriminating fluxes from all ecosystem types, as well as between nearshore and coastal areas a few kilometers distant. Aircraft-derived average midday CO 2 fluxes from the desert showed a slight uptake of 21.32 mmol CO 2 m 22 s 21 , the coastal ocean also showed an uptake of 23.48 mmol CO 2 m 22 s 21 , and the lagoon mangroves showed the highest uptake of 28.11 mmol CO 2 m 22 s 21. Additional simultaneous measurements of the normalized difference vegetation index (NDVI) allowed simple linear modeling of CO 2 flux as a function of NDVI for the mangroves of the Magdalena Bay region. Aircraft approaches can, therefore, be instrumental in determining regional CO 2 fluxes and can be pivotal in calculating and verifying ecosystem carbon sequestration regionally when coupled with satellite-derived products and ecosystem models.

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Application of Footprint Models to Different Measurement Techniques

Leclerc

Foken

2014

Footprints in Micrometeorology and Ecology

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An aircraft-based data analysis method for discerning individual fluxes in a heterogeneous agricultural landscape

Cited by 26 publications

References 35 publications

Arctic regional methane fluxes by ecotope as derived using eddy covariance from a low-flying aircraft

Arctic regional methane fluxes by ecotope as derived using eddy covariance from a low-flying aircraft

Aircraft Regional-Scale Flux Measurements over Complex Landscapes of Mangroves, Desert, and Marine Ecosystems of Magdalena Bay, Mexico

Application of Footprint Models to Different Measurement Techniques

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