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dc.contributor.author
Graf, Manuel
dc.contributor.supervisor
Peter, Thomas
dc.contributor.supervisor
Tuzson, Béla
dc.contributor.supervisor
Emmenegger, Lukas
dc.contributor.supervisor
Dirksen, Ruud
dc.date.accessioned
2020-08-03T13:35:50Z
dc.date.available
2020-08-03T13:27:40Z
dc.date.available
2020-08-03T13:35:50Z
dc.date.issued
2020
dc.identifier.uri
http://hdl.handle.net/20.500.11850/429788
dc.identifier.doi
10.3929/ethz-b-000429788
dc.description.abstract
The radiative balance of the Earth is particularly affected by the abundance of water vapor, not only in the lower troposphere, but also in the upper troposphere and lower stratosphere (UTLS). Understanding the mechanisms that control UTLS water vapor, as well as its long-term variation, is important for reliable projections of the evolution of the global climate system. However, these insights are currently limited by the lack of accurate, frequent, and comparable water vapor measurements in the UTLS. In this project, an open-path direct laser absorption spectrometer is developed, sufficiently small and lightweight to be deployed aboard of meteorological balloons. Its low weight (3.9 kg) and compactness (30 x 23 x 11 cm3) inherently reduces sources of contamination and allows flexible and frequent soundings. The instrument incorporates a quantum cascade laser as a rapidly tunable narrowband light source in the mid-infrared spectral region, where H2O exhibits strong absorption lines. To achieve enhanced robustness, while satisfying the stringent mass limitation, the optical and electronic concept is completely reconsidered with respect to laboratory-based spectrometers. This comprises the elaboration of a lightweight and compact multipass cell concept, called the segmented circular multipass cell (SC-MPC), which enables the reduction of the optical setup to its basic components only, i.e., the laser, the MPC, and the detector. Furthermore, the instrument incorporates custom-developed electronics for fast and power-saving laser driving, data-acquisition hardware based on field-programmable gate arrays (FPGA), dedicated software for controlling and monitoring, and a thermal stabilization system that suppresses the external temperature variation by almost four orders of magnitude. The spectrometer is a fully integrated, standalone system, operating autonomously for the duration of a balloon flight. The H2O concentration is retrieved by calibration-free evaluation of the spectral data, i.e., only relying on SI-traceable measurements and absorption line parameters provided by spectral databases. Laboratory-based characterization experiments demonstrate an agreement within 2% to a reference. In a first balloon-borne test campaign, the instrument was successfully deployed up to the UTLS in two consecutive flights. The comparison to CFH shows a mean deviation of 3% in the troposphere. At higher altitude, accumulated humidity within the enclosure of the instrument currently leads to interference with the atmospheric absorption signal. Despite this restriction, the tests demonstrate the feasibility of spectroscopic water vapor measurements in the UTLS at an effective temporal resolution of 1 Hz during ascent and descent.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.title
Balloon-borne Atmospheric Water Vapor Measurement by Laser Absorption Spectroscopy
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
ethz.size
99 p.
en_US
ethz.code.ddc
DDC - DDC::5 - Science::550 - Earth sciences
en_US
ethz.code.ddc
DDC - DDC::5 - Science::530 - Physics
en_US
ethz.identifier.diss
26662
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02717 - Institut für Atmosphäre und Klima / Inst. Atmospheric and Climate Science::03517 - Peter, Thomas (emeritus) / Peter, Thomas (emeritus)
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02350 - Dep. Umweltsystemwissenschaften / Dep. of Environmental Systems Science::02717 - Institut für Atmosphäre und Klima / Inst. Atmospheric and Climate Science::03517 - Peter, Thomas (emeritus) / Peter, Thomas (emeritus)
en_US
ethz.date.deposited
2020-08-03T13:27:55Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2020-08-03T13:36:16Z
ethz.rosetta.lastUpdated
2023-02-06T20:15:31Z
ethz.rosetta.versionExported
true
ethz.COinS
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