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| Titel |
COCAP - A compact carbon dioxide analyser for airborne platforms |
| VerfasserIn |
Martin Kunz, Jošt V. Lavrič, Wieland Jeschag, Maksym Bryzgalov, Bertil Hök, Martin Heimann |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091678
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| Publikation (Nr.) |
 EGU/EGU2014-5982.pdf |
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| Zusammenfassung |
| Airborne platforms are a valuable tool for atmospheric trace gas measurements due to their
capability of movement in three dimensions, covering spatial scales from metres to thousands
of kilometres. Although crewed research aircraft are flexible in payload and range, their use is
limited by high initial and operating costs. Small unmanned aerial vehicles (UAV) have the
potential for substantial cost reduction, but require lightweight, miniaturized and
energy-efficient scientific equipment.
We are developing a COmpact Carbon dioxide analyser for Airborne Platforms
(COCAP). It contains a non-dispersive infrared CO2sensor with a nominal full scale of
3000μmol/mol. Sampled air is dried with magnesium perchlorate before it enters the sensor.
This enables measurement of the dry air mole fraction of CO2, as recommended by the World
Meteorological Organization. During post-processing, the CO2 measurement is corrected for
temperature and pressure variations in the gas line. Allan variance analysis shows that we
achieve a precision of better than 0.4 μmol/mol for 10 s averaging time. We plan to monitor
the analyser’s stability during flight by measuring reference air from a miniature gas tank in
regular intervals.
Besides CO2, COCAP measures relative humidity, temperature and pressure of ambient
air. An on-board GPS receiver delivers accurate timestamps and allows georeferencing. Data
is both stored on a microSD card and simultaneously transferred over a wireless serial
interface to a ground station for real-time review. The target weight for COCAP is less than 1
kg.
We deploy COCAP on a commercially available fixed-wing UAV (Bormatec Explorer)
with a wingspan of 2.2 metres. The UAV has high payload capacity (2.5 kg) as well as
sufficient space in the fuselage (80x80x600 mm3). It is built from a shock-resistant foam
material, which allows quick repair of minor damages in the field. In case of severe damage
spare parts are readily available. Calculations suggest that the UAV can reach a maximum
altitude of 2000 metres.
COCAP will aid in interpreting ground-based trace gas measurements by profiling the
lower troposphere. In addition, transport modelling around measurement sites can be
improved by assimilating the profiles-derived mixed layer height. Furthermore, COCAP is a
promising tool for the identification of CO2 point sources, e.g. leaking carbon storage sites. |
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