Highly precise and continuous atmospheric O2 measurements

Iersel, Bram van (2021) Highly precise and continuous atmospheric O2 measurements. Bachelor's Thesis, Physics.

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Abstract

A previously built system to measure atmospheric CO2 and O2 continuously has been tested on its new performance figures after recent updates. The most important updates were made to the switching time of two flow lines. The goal of these changes was to improve the δ(O2/N2) precision. The measurements were performed during springtime at the University of Groningen at the CIO labs. The system uses a fuel cell to measure O2 and a compact infrared absorption instrument for CO2 measurements. Data from twelve consecutive days is presented and the performance figures were determined from this period. Cylinder CO2 precisions were found to be 0.08 ppm. The atmospheric CO2 precisions (during stable hours) were found to be 0.13 - 0.32 ppm, which is at the limit of atmospheric variability. The CO2 measurement results are also used to account for its diluting effect on oxygen measurements. For cylinder δ(O2/N2) measurements, precisions were found to be 8 per meg. While atmospheric δ(O2/N2) precisions (during stable hours) were found to be 4 - 8 per meg δ(O2/N2). However, there is a high uncertainty in the δ(O2/N2) precisions due to poor calibration. Only one calibration cylinder δ(O2/N2) value could be determined on a mass spectrometer and the others were instead estimated using the atmospheric potential oxygen (APO). This estimation increases the error in δ(O2/N2) massively. The measured exchange ratios for O2:CO2 events were compared with the expected ratios.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Meijer, H.A.J.
Degree programme:	Physics
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	22 Jul 2021 11:33
Last Modified:	22 Jul 2021 11:33
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/25401

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