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| Titel |
Greenhouse Observations of the Stratosphere and Troposphere (GHOST): a novel shortwave infrared spectrometer developed for the Global Hawk unmanned aerial vehicle |
| VerfasserIn |
Neil Humpage, Hartmut Boesch, Paul Palmer, Phil Parr-Burman, Andy Vick, Naidu Bezawada, Martin Black, Andy Born, David Pearson, Jonathan Strachan, Martyn Wells |
| 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 |
250089972
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| Publikation (Nr.) |
 EGU/EGU2014-4185.pdf |
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| Zusammenfassung |
| The tropospheric distribution of greenhouse gases (GHGs) is dependent on surface flux
variations, atmospheric chemistry and transport processes over a wide range of spatial and
temporal scales. Errors in assumed atmospheric transport can adversely affect surface flux
estimates inferred from surface, aircraft or satellite observations of greenhouse gas
concentrations using inverse models. We present a novel, compact shortwave infrared
spectrometer (GHOST) for installation on the NASA Global Hawk unmanned aerial vehicle
to provide tropospheric column observations of CO2, CO, CH4, H2O and HDO over the
ocean to address the need for large-scale, simultaneous, finely resolved measurements of
key GHGs. These species cover a range of lifetimes and source processes, and
measurements of their tropospheric columns will reflect the vertically integrated signal of
their vertical and horizontal transport within the troposphere. The primary science
objectives of GHOST are to: 1) provide observations which can be used to test
atmospheric transport models; 2) validate satellite observations of GHG column
observations over oceans, thus filling a critical gap in current validation capabilities; and
3) complement in-situ tropopause transition layer tracer observations from other
instrumentation on board the Global Hawk to provide a link between upper and lower
troposphere concentration measurements. The GHOST spectrometer system comprises a
target acquisition module (TAM), a fibre slicer and feed system, and a multiple
order spectrograph. The TAM design utilises a gimbal behind an optical dome,
which is programmed to direct solar radiation reflected by the ocean surface into a
fibre optic bundle. The fibre slicer and feed system then splits the light into the
four spectral bands using order sorting filters. The fibres corresponding to each
band are arranged with a small sideways offset to correctly centre each spectrum
on the detector array. The spectrograph design is unique in that a single grating
and detector is used for all four spectral bands. The whole instrument is housed
within a liquid nitrogen cooled cryostat to ensure thermal stability. We summarise
the GHOST project and its objectives, and will provide a detailed overview of the
instrument concept, development, and proposed deployment on board the Global
Hawk. |
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