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

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.

Air of the Anthropocene

2021 ◽  
Author(s):  
Francis Pope ◽  
Robin Price
Keyword(s):  
Air Pollution ◽  
Los Angeles ◽  
Low Cost ◽  
Measurement Techniques ◽  
Transformational Change ◽  
Ambient Air ◽  
Expert Advice ◽  
Light Sources ◽  
Anthropogenic Contamination ◽  
Science Collaboration

&lt;p&gt;Anthropogenic contamination of the atmosphere is causing both climate change and air pollution, which respectively represent the greatest long term and short term environmental risks to human and planetary health. The contamination is largely invisible and hence difficult to contextualise for non-expert audiences. This can lead to the problem being ignored; or where it is acknowledged, leading to feelings of helplessness and a lack of agency.&lt;/p&gt;&lt;p&gt;This project uses digital light painting to visualise and explore responses to particulate matter (PM) air pollution, in a variety of global locations, as a method for both public engagement and campaign work. This photographic technique combines long exposure with light sources digitally controlled by sensors, it builds upon the prior work of electronic pioneer Steve Mann (e.g. Mann et al. 2019) and more recent work visualising wifi strength (Arnall et al. 2013).&lt;/p&gt;&lt;p&gt;The five year art-science collaboration between Price and Pope has been highly successful. The Air of the Anthropocene project resulted in multiple gallery shows (including Los Angeles, Belfast and Birmingham). The media publicized it heavily, including Source Magazine, New Scientist and the Guardian. The physical art works were acquired by the Arts Council of Northern Ireland&amp;#8217;s public collection.&lt;/p&gt;&lt;p&gt;In this presentation, we will highlight the scientific and aesthetic underpinnings of the use of low cost air pollution sensors for data visualisation through light painting. Locations for visualizations were guided by expert advice from environmental scientists in global locations, including those in Europe, Africa, Asia and South America. In this sense the science informed the art. Also, since the code from the project ended being used by scientists, the art informed the science (e.g. Crilley et al. 2018).&lt;/p&gt;&lt;p&gt;We will highlight the efficacy of this image making approach as an engagement and advocacy tool, through case studies of its use in field campaigns in Ethiopia (2020) and Kampala (2018), investigating both indoor and outdoor air pollution.&amp;#160; Future possibilities of the approach to air pollution visualization will be discussed. This will include expanding the approach through open sourcing the project and its adaptation beyond lens based techniques into augmented reality camera phone use.&lt;/p&gt;&lt;p&gt;The projected next phase of the collaboration will work towards empowering interested citizens of the world to make their own creative, aesthetic representations of their environment and use these images as citizen activists to affect transformational change in their own localities. Through adopting open source methodologies it is hoped that sustainability beyond the timescale and budget of the initial project with lasting legacy will be achieved.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Arnall et al, 2013. Immaterials: light painting WiFi. Significance, 10(4). https://doi.org/10.1111/j.1740-9713.2013.00683.x&amp;#160;&lt;/p&gt;&lt;p&gt;Crilley et al, 2018. Evaluation of a low-cost optical particle counter (Alphasense OPC-N2) for ambient air monitoring. Atmospheric Measurement Techniques. https://doi.org/10.5194/amt-11-709-2018&amp;#160;&lt;/p&gt;&lt;p&gt;Mann et al 2019, June. Making Sensors Tangible with Long-exposure Photography. In The 5th ACM Workshop on Wearable Systems and Applications. https://doi.org/10.1145/3325424.3329668&lt;/p&gt;

scholarly journals Quantitative evaluation of seven optical sensors for cloud microphysical measurements at the Puy-de-Dôme Observatory, France

2015 ◽  
Vol 8 (10) ◽  
pp. 4347-4367 ◽  
Author(s):  
G. Guyot ◽  
C. Gourbeyre ◽  
G. Febvre ◽  
V. Shcherbakov ◽  
F. Burnet ◽  
...  
Keyword(s):  
Optical Properties ◽  
Wind Tunnel ◽  
Optical Sensors ◽  
Wind Direction ◽  
Total Concentration ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Number Concentration ◽  
Effective Diameter ◽  
Particle Volume

Abstract. Clouds have an important role in Earth's radiative budget. Since the late 1970s, considerable instrumental developments have been made in order to quantify cloud microphysical and optical properties, for both airborne and ground-based applications. Intercomparison studies have been carried out in the past to assess the reliability of cloud microphysical properties inferred from various measurement techniques. However, observational uncertainties still exist, especially for droplet size distribution measurements and need to be reduced. In this work, we discuss results from an intercomparison campaign, performed at the Puy de Dôme in May 2013. During this campaign, a unique set of cloud instruments was operating simultaneously in ambient air conditions and in a wind tunnel. A Particle Volume Monitor (PVM-100), a Forward Scattering Spectrometer Probe (FSSP), a Fog Monitor (FM-100), and a Present Weather Detector (PWD) were sampling on the roof of the station. Within a wind tunnel located underneath the roof, two Cloud Droplet Probes (CDPs) and a modified FSSP (SPP-100) were operating. The main objectives of this paper are (1) to study the effects of wind direction and speed on ground-based cloud observations, (2) to quantify the cloud parameters discrepancies observed by the different instruments, and (3) to develop methods to improve the quantification of the measurements. The results revealed that all instruments showed a good agreement in their sizing abilities, both in terms of amplitude and variability. However, some of them, especially the FM-100, the FSSP and the SPP, displayed large discrepancies in their capability to assess the magnitude of the total number concentration of the cloud droplets. As a result, the total liquid water content can differ by up to a factor of 5 between the probes. The use of a standardization procedure, based on data of integrating probes (PVM-100 or visibilimeter) and extinction coefficient comparison substantially enhanced the instrumental agreement. During this experiment, the total concentration agreed in variations with the visibilimeter, except for the FSSP, so a corrective factor can be applied and it ranges from 0.44 to 2.2. This intercomparison study highlights the necessity to have an instrument which provides a bulk measurement of cloud microphysical or optical properties during cloud ground-based campaigns. Moreover, the FM and FSSP orientation was modified with an angle ranging from 30 to 90° angle with wind speeds from 3 to 7 m s−1. The results show that the induced number concentration loss is between 29 and 98 % for the FSSP and between 15 and 68 % for the FM-100. In particular, FSSP experiments showed strong discrepancies when the wind speed was lower than 3 m s−1 and/or when the angle between the wind direction and the orientation of the instruments is greater than 30°. An inadequate orientation of the FSSP towards the wind direction leads to an underestimation of the measured effective diameter.

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 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.

Novel stable isotopic measurements for understanding atmospheric methane

2021 ◽  
Author(s):  
Chris Rennick ◽  
Ed Chung ◽  
Tim Arnold ◽  
Emmal Safi ◽  
Alice Drinkwater ◽  
...  
Keyword(s):  
Inverse Method ◽  
Dispersion Model ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Isotope Ratios ◽  
Reaction Rates ◽  
Particle Dispersion ◽  
Added Value ◽  
Atmospheric Methane ◽  
Air Sample

&lt;p&gt;We demonstrate the possibilities for continuous high precision in situ measurements of &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C(CH&lt;sub&gt;4&lt;/sub&gt;) and &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H(CH&lt;sub&gt;4&lt;/sub&gt;) for understanding regional CH&lt;sub&gt;4&lt;/sub&gt; emissions and explain how advances in nascent measurement techniques looking at &amp;#8216;clumped&amp;#8217; CH&lt;sub&gt;4&lt;/sub&gt; might improve our understanding on the global scale.&lt;/p&gt;&lt;p&gt;&amp;#8216;Boreas&amp;#8217; is a new fully automated sample-preparation coupled dual laser spectrometer system developed at the National Physical Laboratory, able to make accurate and precise simultaneous measurements of &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C(CH&lt;sub&gt;4&lt;/sub&gt;) and &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H(CH&lt;sub&gt;4&lt;/sub&gt;) through the measurement of isotopologue ratios of CH&lt;sub&gt;4&lt;/sub&gt;. Average daily repeatabilities of &lt;0.08 &amp;#8240; for &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C (n=10, 1 SD) &amp;#160;and &lt;1&amp;#8240; &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H of a compressed &amp;#8216;background&amp;#8217; air sample (1.9 ppm dry air amount fraction CH&lt;sub&gt;4&lt;/sub&gt;) are achieved, making the measurements comparable to bulk isotope ratio mass spectrometry. These measurements are interspersed with air sample measurements from the roof of our building in west London, and we show the possibility to differentiate potential sources of CH&lt;sub&gt;4&lt;/sub&gt; under different meteorological conditions.&lt;/p&gt;&lt;p&gt;We use a particle dispersion model (the Met Office&amp;#8217;s NAME) and inverse method to predict the possible impact of the new continuous isotope ratios measurements on quantification of emissions from individual source sectors, should the technique be deployed to a tall tower network of monitoring sites in the UK.&lt;/p&gt;&lt;p&gt;Finally, our theoretical analysis is extended beyond the most abundant isotopologues of CH&lt;sub&gt;4&lt;/sub&gt; to look at how analysis of the clumped isotopes might be able to impact our understanding of interannual variability in the global CH&lt;sub&gt;4&lt;/sub&gt; burden. We incorporate measurements from emission sources and information on reaction rates into a global box model (with an inverse method) to show the added value of strategic &amp;#8710;CH&lt;sub&gt;2&lt;/sub&gt;D&lt;sub&gt;2&lt;/sub&gt; and &amp;#8710;&lt;sup&gt;13&lt;/sup&gt;CH&lt;sub&gt;3&lt;/sub&gt;D ambient air measurements relative to bulk isotope ratios alone.&lt;/p&gt;

Near-Field and Far-Field Sampling of Aerosol Plumes to Evaluate Particulate Emission Rates From a Falling Particle Receiver During On-Sun Testing

2021 ◽  
Author(s):  
Andrew Glen ◽  
Darielle Dexheimer ◽  
Andres L. Sanchez ◽  
Clifford K. Ho ◽  
Swarup China ◽  
...  
Keyword(s):  
Size Distribution ◽  
Near Field ◽  
Measurement Techniques ◽  
Ambient Air ◽  
Industrial Applications ◽  
Aerosol Size Distribution ◽  
Far Field ◽  
Emission Rates ◽  
Particulate Emission ◽  
Field Instrumentation

Abstract High-temperature falling particle receivers are being investigated for next-generation concentrating solar power applications. Small sand-like particles are released into an open-cavity receiver and are irradiated by concentrated sunlight from a field of heliostats. The particles are heated to temperatures over 700 °C and can be stored to produce heat for electricity generation or industrial applications when needed. As the particles fall through the receiver, particles and particulate fragments in the form of aerosolized dust can be emitted from the aperture, which can lower thermal efficiency, increase costs of particle replacement, and pose a particulate matter (PM) inhalation risk. This paper describes sampling methods that were deployed during on-sun tests to record near-field (several meters) and far-field (tens to hundreds of meters) concentrations of aerosol particles within emitted plumes. The objective was to quantify the particulate emission rates and loss from the falling particle receiver in relation to OSHA and EPA National Ambient Air Quality Standards (NAAQS). Near-field instrumentation placed on the platform in proximity to the receiver aperture included several real-time aerosol size distribution and concentration measurement techniques, including a TSI Aerodynamic Particle Sizers (APS), TSI DustTraks, Handix Portable Optical Particle Spectrometers (POPS), Alphasense Optical Particle Counters (OPC), TSI Condensation Particle Counters (CPC), Cascade Particle Impactors, 3D-printed prototype tipping buckets, and meteorological instrumentation. Far-field particle sampling techniques utilized multiple tethered balloons located upwind and downwind of the particle receiver to measure the advected plume concentrations using a suite of airborne aerosol and meteorological instruments including POPS, CPCs, OPCs and cascade impactors. The combined aerosol size distribution for all these instruments spanned particle sizes from 0.02 μm – 500 μm. Results showed a strong influence of wind direction on particle emissions and concentration, with preliminary results showing representative concentrations below both the OSHA and NAAQS standards.

Comparison of the measurement techniques employed for evaluation of ambient air odor quality

2016 ◽  
Author(s):  
Wojciech Wojnowski ◽  
Tomasz Majchrzak ◽  
Jacek Gębicki ◽  
Tomasz Dymerski ◽  
Jacek Namieśnik
Keyword(s):  
Measurement Techniques ◽  
Ambient Air ◽  
Odor Quality

Comparison of Formaldehyde Measurements by HANTZSCH, CRDS and DOAS instruments in the SAPHIR Chamber

2020 ◽  
Author(s):  
Marvin Glowania ◽  
Hendrik Fuchs ◽  
Franz Rohrer ◽  
Hans-Peter Dorn ◽  
Frank Holland ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Chemical Conversion ◽  
Ambient Air ◽  
Optical Absorption Spectroscopy ◽  
Base Line ◽  
Fluorescence Measurement ◽  
Gas Stripping ◽  
Gas Source ◽  
Acid Titration ◽  
Good Agreement

&lt;p&gt;Three instruments using different measurement techniques were used to measure formaldehyde (HCHO) concentrations during experiments in the atmopshere simulation chamber SAPHIR at the Forschungszentrum Juelich. An AL4021 instrument by Aero Laser GmbH uses the wet-chemical Hantzsch reaction for efficient gas stripping, chemical conversion and fluorescence measurement. An internal permeation gas source provides daily calibrations characterized by sulfuric acid titration. A G2307 analyzer by PICARRO INC. uses Cavity Ring-Down Spectroscopy (CRDS) technique to determine concentrations of HCHO, water and methane. A high-resolution laser differential optical absorption spectroscopy (DOAS) instrument provided HCHO measurements along the central chamber axis using an optical multiple reflection cell. The measurements were conducted from June to December 2019 in experiments when ambient air was flowed through the chamber and also in photochemical experiments in synthetic air with mixtures of different reactants, water vapour, nitrogen oxides, and ozone concentrations. Results demonstrate the importance for a linear base line interpolation between zero measurements for the Hantzsch instrument. In addition, a strong water dependence of the baseline of CRDS measurements was found. After correction for the baselines, the correlation analysis of measurements demonstrate good agreement (R &gt; 0.98) between the instruments.&lt;/p&gt;

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