COCAP: a carbon dioxide analyser for small unmanned aircraft systems

Kunz, Martin; Lavrič, Jošt V.; Gerbig, Christoph; Tans, Pieter P.; Neff, D. H.; Hummelgård, Christine; Martin, H.; Rödjegård, Henrik; Wrenger, Burkhard; Heimann, Martin

doi:10.5194/amt-11-1833-2018

Cited by 28 publications

(27 citation statements)

References 21 publications

(24 reference statements)

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“…For the study presented here, temperature, pressure, relative humidity and CO 2 dry-air mole fraction of ambient air were measured using COCAP, the COmpact Carbon dioxide analyser for Airborne Platforms, developed at the Max Planck Institute for Biogeochemistry in Jena (see Kunz et al, 2018, for a detailed description). COCAP was mounted below the multicopter.…”

Section: Airborne Payloadmentioning

confidence: 99%

“…Ignoring noise and calibration error, any CO 2 signal x a is reported by COCAP as the convolution of x a with the CO 2 sensor's instrument function f (see Kunz et al, 2018):…”

Section: Correction For Response Time Of Sensorsmentioning

confidence: 99%

“…UASs with payload capacities on the order of 1 kg are now available for a few thousand euros. When equipped with lightweight trace gas analysers and meteorological sensors (Kunz et al, 2018), they have the potential to probe the NBL with large flexibility at low cost. Multicopters are a particularly attractive type of UAS for this kind of study, because their vertical take-off, vertical landing and hovering capability makes them easy to operate in a range of environments.…”

Section: Introductionmentioning

confidence: 99%

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Surface flux estimates derived from UAS-based mole fraction measurements by means of a nocturnal boundary layer budget approach

et al. 2020

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Abstract. The carbon exchange between ecosystems and the atmosphere has a large influence on the Earth system and specifically on the climate. This exchange is therefore being studied intensively, often using the eddy covariance (EC) technique. EC measurements provide reliable results under turbulent atmospheric conditions, but under calm and stable conditions – as they often occur at night – these measurements are known to misrepresent exchange fluxes. Nocturnal boundary layer (NBL) budgets can provide independent flux estimates under stable conditions, but their application so far has been limited by rather high cost and practical difficulties. Unmanned aircraft systems (UASs) equipped with trace gas analysers have the potential to make this method more accessible. We present the methodology and results of a proof-of-concept study carried out during the ScaleX 2016 campaign. Successive vertical profiles of carbon dioxide dry-air mole fraction in the NBL were taken with a compact analyser carried by a UAS. We estimate an average carbon dioxide flux of 12 µmolm-2s-1, which is plausible for nocturnal respiration in this region in summer. Transport modelling suggests that the NBL budgets represent an area on the order of 100 km2.

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Section: Airborne Payloadmentioning

confidence: 99%

“…Ignoring noise and calibration error, any CO 2 signal x a is reported by COCAP as the convolution of x a with the CO 2 sensor's instrument function f (see Kunz et al, 2018):…”

Section: Correction For Response Time Of Sensorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface flux estimates derived from UAS-based mole fraction measurements by means of a nocturnal boundary layer budget approach

et al. 2020

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“…The flux footprint is calculated by integration over an array of mole fraction footprints for different measurement heights, i.e. analogous to Equation 11 term A and Equation 12: The uncertainty of COCAP's x CO2 measurements due to drift and calibration errors is about 1 µmol·mol −1 (Kunz et al, 2018).…”

Section: Footprint Calculationmentioning

confidence: 99%

Surface flux estimates derived from UAS-based mole fraction measurements by means of a nocturnal boundary layer budget approach

Kunz¹,

Lavrič²,

Gasché³

et al. 2019

Preprint

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The carbon exchange between ecosystems and the atmosphere has a large influence on the Earth system and specifically on the climate. This exchange is therefore being studied intensively, often using the eddy covariance (EC) technique.EC measurements provide reliable results under turbulent atmospheric conditions, but under stable conditions -as they often occur at night -these measurements are known to misrepresent exchange fluxes. Nocturnal boundary layer (NBL) budgets can provide independent flux estimates under stable conditions, but their application so far has been limited by rather high cost 5 and practical difficulties. Unmanned aircraft systems (UASs) equipped with trace gas analysers have the potential to make this method more accessible. We present the methodology and results of a proof of concept study carried out during the ScaleX 2016 campaign. Successive vertical profiles of carbon dioxide dry air mole fraction in the NBL were taken with a compact analyser carried by a UAS. We estimate an average carbon dioxide flux of 12 µmol · m −2 · s −1 , which is plausible for nocturnal respiration in this region in summer. Transport modelling suggests that the NBL budgets represent an area on the order of 10 100 km².

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“…Previous studies include the investigation of temporal and spatial variations of atmospheric CO 2 using a unique CO 2 measurement device attached to a small UAV (kite plane) (Watai et al, 2006); atmospheric monitoring of point source fossil fuel CO 2 and CH 4 from a gas treatment plant using a Helikite (Turnbull et al, 2014); CO 2 , CH 4 , and H 2 O measurements on board the National Aeronautics and Space Administration (NASA) Sensor Integrated Environmental Remote Research Aircraft (SIERRA) UAV (Berman et al, 2012); a small atmospheric sensor measuring CO 2 , CH 4 , and H 2 O attached to a robotic helicopter (Khan et al, 2012); the quantification of CH 4 mole fractions and isotopic compositions from heights up to 2700 m on Ascension Island using a remotely piloted octocopter (Lowry et al, 2015;Brownlow et al, 2016); and a dedicated CO 2 analyzer, COmpact Carbon dioxide analyzer for Airborne Platforms (CO-CAP), capable of being flown onboard small UAVs (Kunz et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

A UAV-based active AirCore system for measurements of greenhouse gases

et al. 2018

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Abstract.We developed and field-tested an unmanned aerial vehicle (UAV)-based active AirCore for atmospheric mole fraction measurements of CO 2 , CH 4 , and CO. The system applies an alternative way of using the AirCore technique invented by NOAA. As opposed to the conventional concept of passively sampling air using the atmospheric pressure gradient during descent, the active AirCore collects atmospheric air samples using a pump to pull the air through the tube during flight, which opens up the possibility to spatially sample atmospheric air. The active AirCore system used for this study weighs ∼ 1.1 kg. It consists of a ∼ 50 m long stainlesssteel tube, a small stainless-steel tube filled with magnesium perchlorate, a KNF micropump, and a 45 µm orifice working together to form a critical flow of dried atmospheric air through the active AirCore. A cavity ring-down spectrometer (CRDS) was used to analyze the air samples on site not more than 7 min after landing for mole fraction measurements of CO 2 , CH 4 , and CO. We flew the active AirCore system on a UAV near the atmospheric measurement station at Lutjewad, located in the northwest of the city of Groningen in the Netherlands. Five consecutive flights took place over a 5 h period on the same morning, from sunrise until noon. We validated the measurements of CO 2 and CH 4 from the active AirCore against those from the Lutjewad station at 60 m. The results show a good agreement between the measurements from the active AirCore and the atmospheric station (N = 146; R 2 CO 2 : 0.97 and R 2 CH 4 : 0.94; and mean differences: CO 2 : 0.18 ppm and CH 4 : 5.13 ppb). The vertical and horizontal resolution (for CH 4 ) at typical UAV speeds of 1.5 and 2.5 m s −1 were determined to be ±24.7 to 29.3 and ±41.2 to 48.9 m, respectively, depending on the storage time. The collapse of the nocturnal boundary layer and the buildup of the mixed layer were clearly observed with three consecutive vertical profile measurements in the early morning hours. Besides this, we furthermore detected a CH 4 hotspot in the coastal wetlands from a horizontal flight north to the dike, which demonstrates the potential of this new active AirCore method to measure at locations where other techniques have no practical access.

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COCAP: a carbon dioxide analyser for small unmanned aircraft systems

Cited by 28 publications

References 21 publications

Surface flux estimates derived from UAS-based mole fraction measurements by means of a nocturnal boundary layer budget approach

Surface flux estimates derived from UAS-based mole fraction measurements by means of a nocturnal boundary layer budget approach

Surface flux estimates derived from UAS-based mole fraction measurements by means of a nocturnal boundary layer budget approach

A UAV-based active AirCore system for measurements of greenhouse gases

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