scholarly journals High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques

2019 ◽  
Vol 12 (12) ◽  
pp. 6803-6826
Author(s):  
Tesfaye A. Berhanu ◽  
John Hoffnagle ◽  
Chris Rella ◽  
David Kimhak ◽  
Peter Nyfeler ◽  
...  
Keyword(s):  
High Precision ◽  
Atmospheric Oxygen ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Field Studies ◽  
Research Station ◽  
Mixing Ratio ◽  
Gas Combustion ◽  
Tightly Coupled ◽  
Oxidation Ratio

Abstract. Carbon dioxide and oxygen are tightly coupled in land biosphere CO2–O2 exchange processes, whereas they are not coupled in oceanic exchange. For this reason, atmospheric oxygen measurements can be used to constrain the global carbon cycle, especially oceanic uptake. However, accurately quantifying small (∼1–100 ppm) variations in O2 is analytically challenging due to the very large atmospheric background which constitutes about 20.9 % (∼209 500 ppm) of atmospheric air. Here we present a detailed description of a newly developed high-precision oxygen mixing ratio and isotopic composition analyzer (Picarro G2207) that is based on cavity ring-down spectroscopy (CRDS) as well as to its operating principles; we also demonstrate comprehensive laboratory and field studies using the abovementioned instrument. From the laboratory tests, we calculated a short-term precision (standard error of 1 min O2 mixing ratio measurements) of < 1 ppm for this analyzer based on measurements of eight standard gases analyzed for 2 h, respectively. In contrast to the currently existing techniques, the instrument has an excellent long-term stability; therefore, calibration every 12 h is sufficient to get an overall uncertainty of < 5 ppm. Measurements of ambient air were also conducted at the Jungfraujoch high-altitude research station and the Beromünster tall tower in Switzerland. At both sites, we observed opposing and diurnally varying CO2 and O2 profiles due to different processes such as combustion, photosynthesis, and respiration. Based on the combined measurements at Beromünster tower, we determined height-dependent O2:CO2 oxidation ratios varying between −0.98 and −1.60; these ratios increased with the height of the tower inlet, possibly due to different source contributions such as natural gas combustion, which has a high oxidation ratio, and biological processes, which have oxidation ratios that are relatively lower.

scholarly journals High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques

2019 ◽  
Author(s):  
Tesfaye A. Berhanu ◽  
John Hoffnagle ◽  
Chris Rella ◽  
David Kimhak ◽  
Peter Nyfeler ◽  
...  
Keyword(s):  
High Precision ◽  
Atmospheric Oxygen ◽  
Measurement Techniques ◽  
Field Studies ◽  
Exchange Processes ◽  
Tightly Coupled ◽  
Composition Analyzer ◽  
Oxygen Measurement ◽  
Oxygen Measurements ◽  
Global Carbon

Abstract. Carbon dioxide and oxygen are tightly coupled in land–biospheres CO2–O2 exchange processes, while they are not coupled in oceanic exchange. For this reason, atmospheric oxygen measurements can be used to constrain the global carbon cycle, especially oceanic uptake. However, accurately quantifying the small (~ 1–100 ppm) variations in O2 is analytically challenging due to the very large atmospheric background which constitutes about 20.9 % (~ 209 500 ppm) of atmospheric air. Here we present comprehensive laboratory and field studies for a newly developed high-precision oxygen mixing ratio and isotopic composition analyzer (Picarro G-2207) that is based on cavity ring-down spectroscopy (CRDS). From the laboratory tests, we have calculated a short-term precision (standard error of one-minute measurements) of

scholarly journals Comparison of continuous in-situ CO<sub>2</sub> observations at Jungfraujoch using two different measurement techniques

2014 ◽  
Vol 7 (7) ◽  
pp. 7053-7084
Author(s):  
M. F. Schibig ◽  
M. Steinbacher ◽  
B. Buchmann ◽  
I. T. van der Laan-Luijkx ◽  
S. van der Laan ◽  
...  
Keyword(s):  
Materials Science ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Pollution Monitoring ◽  
Smooth Transition ◽  
Research Station ◽  
Short Term ◽  
Technical Problems ◽  
Two Systems ◽  
Data Coverage

Abstract. Since 2004, atmospheric carbon dioxide (CO2) is measured at the High Altitude Research Station Jungfraujoch by the division of Climate and Environmental Physics at the University of Bern (KUP) using a nondispersive infrared gas analyzer (NDIR) in combination with a paramagnetic O2 analyzer. In January 2010, CO2 measurements based on cavity ring down spectroscopy (CRDS) as part of the Swiss National Air Pollution Monitoring Network have been added by the Swiss Federal Laboratories for Materials Science and Technology (Empa). To ensure a smooth transition – a prerequisite when merging two datasets e.g. for trend determinations – the two measurement systems run in parallel for several years. Such a long-term intercomparison also allows identifying potential offsets between the two datasets and getting information about the compatibility of the two systems on different time scales. A good agreement of the seasonality as well as for the short-term variations was observed and to a lesser extent for trend calculations mainly due to the short common period. However, the comparison revealed some issues related to the stability of the calibration gases of the KUP system and their assigned CO2 mole fraction. It was possible to adapt an improved calibration strategy based on standard gas determinations, which lead to better agreement between the two data sets. By excluding periods with technical problems and bad calibration gas cylinders, the average hourly difference (CRDS − NDIR) of the two systems is −0.03 ppm ± 0.25 ppm. Although the difference of the two datasets is in line with the compatibility goal of ±0.1 ppm of the World Meteorological Organization (WMO), the standard deviation is still too high. A significant part of this uncertainty originates from the necessity to switch the KUP system frequently (every 12 min) for 6 min from ambient air to a working gas in order to correct short-term variations of the O2 measurement system. Allowing additionally for signal stabilization after switching the sample, an effective data coverage of only 1/6 for the KUP system is achieved while the Empa system has a nearly complete data coverage. Additionally, different internal volumes and flow rates between the two systems may affect observed differences.

Development and characterization of a high precision QCLAS for selective NO2 measurement

2020 ◽  
Author(s):  
Nicolas Sobanski ◽  
Beat Schwarzenbach ◽  
Béla Tuzson ◽  
Lukas Emmenegger ◽  
Dave R. Worton ◽  
...  
Keyword(s):  
Nitrogen Dioxide ◽  
High Precision ◽  
Anthropogenic Activities ◽  
Ambient Pressure ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Low Noise ◽  
Pollution Monitoring ◽  
Urban Air ◽  
Custom Made

&lt;p&gt;&amp;#160;&amp;#160; Nitrogen dioxide (NO&lt;sub&gt;2&lt;/sub&gt;) is an atmospheric pollutant whose emissions are mostly linked to anthropogenic activities. It is, with nitric oxide (NO), the most abundant member of the nitrogen oxides family in tropospheric urban air (mixing ratios up to hundreds of ppbv), with a lifetime ranging from hours to days. NO&lt;sub&gt;2&lt;/sub&gt; is well known for its role as a boundary layer ozone and organic nitrates precursor and for affecting the oxidation capacity of the atmosphere. It has thus been subject to emissions mitigation policies and ambient air amount fraction monitoring for a few decades. The latter fully relies on the Chemiluminescence Detection technique (CLD), which is an indirect method measuring NO&lt;sub&gt;2&lt;/sub&gt; after conversion to NO.&lt;br&gt;&amp;#160;&amp;#160; Recent advances in spectroscopy led to the development of direct and more selective ways to measure NO&lt;sub&gt;2&lt;/sub&gt;. The currently running European Metrology for Nitrogen Dioxide (MetNO2) project, involving more than 15 European academic and industrial partners, promises to fill the gap in reliable and complete datasets for laboratory and field testing of those measurement techniques.&lt;br&gt;Here we present the results of a performance investigation of a high precision Quantum Cascade Laser Absorption Spectrometer (QCLAS) for the selective measurement of NO&lt;sub&gt;2&lt;/sub&gt; performed in the frame of the MetNO2 project. This instrument is based on a mid-IR QCL emitting at 6 &amp;#956;m and a custom-made, low noise astigmatic Herriott type multipass cell with an effective optical path length of 100 m to measure NO&lt;sub&gt;2&lt;/sub&gt; concentration in the low pptv range. We focus on determining precision, long-term stability and potential biases related to sampling conditions such as ambient pressure, temperature and humidity. The QCLAS device is then compared to other direct spectroscopic (CAPS, CRDS, IBBCEAS) and indirect (CLD) techniques. We also report on the results of a three weeks side-by-side field comparison at an urban air monitoring station of the Swiss National Air Pollution Monitoring Network (NABEL), involving the newly developed QCLAS, and commercial CAPS and CLD instruments.&lt;br&gt;&amp;#160;&amp;#160; We show that the QCLAS is well suited for monitoring of NO&lt;sub&gt;2&lt;/sub&gt; concentration in ambient air and its performances in term of precision and stability surpass those of the CLD device and compete well with other direct measurement techniques.&lt;/p&gt;

scholarly journals Comparison of continuous in situ CO<sub>2</sub> observations at Jungfraujoch using two different measurement techniques

2015 ◽  
Vol 8 (1) ◽  
pp. 57-68 ◽  
Author(s):  
M. F. Schibig ◽  
M. Steinbacher ◽  
B. Buchmann ◽  
I. T. van der Laan-Luijkx ◽  
S. van der Laan ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Ambient Air ◽  
Pollution Monitoring ◽  
Smooth Transition ◽  
Research Station ◽  
Data Sets ◽  
Short Term ◽  
Technical Problems ◽  
Two Systems ◽  
Data Coverage

Abstract. Since 2004, atmospheric carbon dioxide (CO2) is being measured at the High Altitude Research Station Jungfraujoch by the division of Climate and Environmental Physics at the University of Bern (KUP) using a nondispersive infrared gas analyzer (NDIR) in combination with a paramagnetic O2 analyzer. In January 2010, CO2 measurements based on cavity ring-down spectroscopy (CRDS) as part of the Swiss National Air Pollution Monitoring Network were added by the Swiss Federal Laboratories for Materials Science and Technology (Empa). To ensure a smooth transition – a prerequisite when merging two data sets, e.g., for trend determinations – the two measurement systems run in parallel for several years. Such a long-term intercomparison also allows the identification of potential offsets between the two data sets and the collection of information about the compatibility of the two systems on different time scales. A good agreement of the seasonality, short-term variations and, to a lesser extent mainly due to the short common period, trend calculations is observed. However, the comparison reveals some issues related to the stability of the calibration gases of the KUP system and their assigned CO2 mole fraction. It is possible to adapt an improved calibration strategy based on standard gas determinations, which leads to better agreement between the two data sets. By excluding periods with technical problems and bad calibration gas cylinders, the average hourly difference (CRDS – NDIR) of the two systems is −0.03 ppm ± 0.25 ppm. Although the difference of the two data sets is in line with the compatibility goal of ±0.1 ppm of the World Meteorological Organization (WMO), the standard deviation is still too high. A significant part of this uncertainty originates from the necessity to switch the KUP system frequently (every 12 min) for 6 min from ambient air to a working gas in order to correct short-term variations of the O2 measurement system. Allowing additional time for signal stabilization after switching the sample, an effective data coverage of only one-sixth for the KUP system is achieved while the Empa system has a nearly complete data coverage. Additionally, different internal volumes and flow rates may affect observed differences.

Field intercomparison of measurement techniques for total NH4+ and total NO3− in ambient air

1988 ◽  
Vol 22 (10) ◽  
pp. 2275-2281 ◽  
Author(s):  
M. Ferm ◽  
H. Areskoug ◽  
J.-E. Hanssen ◽  
G. Hilbert ◽  
H. Lättilä
Keyword(s):  
Measurement Techniques ◽  
Ambient Air ◽  
Field Intercomparison

Removing NOx Pollution by Photocatalytic Building Materials in Real-Life: Evaluation of Existing Field Studies

2021 ◽  
Vol 02 ◽  
Author(s):  
Pernille D. Pedersen ◽  
Nina Lock ◽  
Henrik Jensen
Keyword(s):  
Air Pollutants ◽  
Building Materials ◽  
Evaluation Criteria ◽  
Real Life ◽  
Ambient Air ◽  
Well Being ◽  
Good Health ◽  
Objective Evaluation ◽  
Field Studies ◽  
Hazardous Air Pollutants

: The NOx gasses (NO and NO2) are among the most important air pollutants, due to the toxicity of NO2, as well as the role of NOx in the tropospheric oxidation of Volatile Organic Carbons (VOCs), contributing to the formation of other hazardous air pollutants. Air pollution is one of the biggest health threats world-wide, hence reducing NOx levels is an important objective of the UN sustainable development goals, e.g. #3, “Good health and well-being” and #11 “Sustainable cities and communities”. Photocatalysis using TiO2 and light is a promising technique for removing NOx along with other pollutants, as demonstrated on laboratory scale. Furthermore, a long range of real-life test studies of varying scales have been conducted during the past two decades. The results of these studies have been conflicting, with some studies reporting no effect on the ambient air quality and others reporting significant reductions of NOx level. However, the studies are very difficult to compare and assess due to the very different approaches used, which consequently vary in quality. In this review, we aim to develop a set of objective evaluation criteria to assess the quality of the individual studies in order to simplify the interpretation and comparison of the existing studies. Moreover, we propose some guidelines for future test-studies. Furthermore, the approaches and main conclusions from 23 studies are independently assessed and discussed herein.

scholarly journals In-situ observations of the isotopic composition of methane at the Cabauw tall tower site

2016 ◽  
Author(s):  
Thomas Röckmann ◽  
Simon Eyer ◽  
Carina van der Veen ◽  
Maria E. Popa ◽  
Béla Tuzson ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
High Precision ◽  
Temporal Resolution ◽  
Isotope Ratio ◽  
Mesoscale Model ◽  
Ambient Air ◽  
Model Calculations ◽  
Dual Isotope ◽  
Methane Budget

Abstract. High precision analyses of the isotopic composition of methane in ambient air can potentially be used to discriminate between different source categories. Due to the complexity of isotope ratio measurements, such analyses have generally been performed in the laboratory on air samples collected in the field. This poses a limitation on the temporal resolution at which the isotopic composition can be monitored with reasonable logistical effort. Here we present the performance of a dual isotope ratio mass spectrometric system (IRMS) and a quantum cascade laser absorption spectroscopy (QCLAS) based technique for in-situ analysis of the isotopic composition of methane under field conditions. Both systems were deployed at the Cabauw experimental site for atmospheric research (CESAR) in the Netherlands and performed in-situ, high-frequency (approx. hourly) measurements for a period of more than 5 months. The IRMS and QCLAS instruments were in excellent agreement with a slight systematic offset of +(0.05 ± 0.03) ‰ for δ13C and –(3.6 ± 0.4) ‰ for δD. This was corrected for, yielding a combined dataset with more than 2500 measurements of both δ13C and δD. The high precision and temporal resolution dataset does not only reveal the overwhelming contribution of isotopically depleted agricultural CH4 emissions from ruminants at the Cabauw site, but also allows the identification of specific events with elevated contributions from more enriched sources such as natural gas and landfills. The final dataset was compared to model calculations using the global model TM5 and the mesoscale model FLEXPART-COSMO. The results of both models agree better with the measurements when the TNO-MACC emission inventory is used in the models than when the EDGAR inventory is used. This suggests that high-resolution isotope measurements have the potential to further constrain the methane budget, when they are performed at multiple sites that are representative for the entire European domain.

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