scholarly journals Measurements of OH and HO<sub>2</sub> concentrations during the MCMA-2006 field campaign – Part 1: Deployment of the Indiana University laser-induced fluorescence instrument

2008 ◽  
Vol 8 (4) ◽  
pp. 13689-13739 ◽  
Author(s):  
S. Dusanter ◽  
D. Vimal ◽  
P. S. Stevens ◽  
R. Volkamer ◽  
L. T. Molina
Keyword(s):  
Mexico City ◽  
Signal To Noise Ratio ◽  
Field Measurements ◽  
Laser Induced Fluorescence ◽  
Urban Site ◽  
Indiana University ◽  
Field Campaign ◽  
Direct Excitation ◽  
Stage Of Development ◽  
New Instrument

Abstract. Measurements of tropospheric hydroxyl (OH) and hydroperoxy (HO2) radicals were made during the MCMA (Mexico City Metropolitan Area) field campaign as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) project during March 2006. These radicals were measured using a laser-induced fluorescence instrument developed at Indiana University. This new instrument takes advantage of the Fluorescence Assay by Gas Expansion technique (FAGE) together with direct excitation and detection of OH at 308 nm. HO2 is indirectly measured as OH by titration with NO inside the fluorescence cell. At this stage of development, IU-FAGE is capable of detecting 3.9×105molec cm−3 of both OH and HO2, with a signal to noise ratio of 1, an averaged laser power of 10 mW and an averaging time of 5 min. The calibration accuracies (1σ) are ±17% for OH and ±18% for HO2 using the water-vapor photolysis/O2 actinometry calibration technique. OH and HO2 concentrations were successfully measured at an urban site in Mexico City, with observed concentrations comparable to those measured in other polluted environments. Enhanced levels of OH and HO2 radicals were observed on several days between 09:30–11 a.m. and suggest an intense photochemistry during morning hours that may be due to elevated sources of HOx (OH+HO2) and a fast cycling between the radicals under the high NOx conditions of the MCMA. A comparison with other urban and sub-urban field measurements suggests that OH concentrations are highly buffered under these conditions. In contrast, HO2 concentrations are highly variable between different urban sites.

scholarly journals Measurements of OH and HO<sub>2</sub> concentrations during the MCMA-2006 field campaign – Part 1: Deployment of the Indiana University laser-induced fluorescence instrument

2009 ◽  
Vol 9 (5) ◽  
pp. 1665-1685 ◽  
Author(s):  
S. Dusanter ◽  
D. Vimal ◽  
P. S. Stevens ◽  
R. Volkamer ◽  
L. T. Molina
Keyword(s):  
Mexico City ◽  
Signal To Noise Ratio ◽  
Laser Induced Fluorescence ◽  
Urban Site ◽  
Indiana University ◽  
Field Campaign ◽  
Direct Excitation ◽  
Stage Of Development ◽  
New Instrument ◽  
Averaging Time

Abstract. Measurements of tropospheric hydroxyl (OH) and hydroperoxy (HO2) radicals were made during the MCMA (Mexico City Metropolitan Area) field campaign as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) project during March 2006. These radicals were measured using a laser-induced fluorescence instrument developed at Indiana University. This new instrument takes advantage of the Fluorescence Assay by Gas Expansion technique (FAGE) together with direct excitation and detection of OH at 308 nm. HO2 is indirectly measured as OH by titration with NO inside the fluorescence cell. At this stage of development, IU-FAGE is capable of detecting 3.9×105 molecule/cm3 of both OH and HO2, with a signal to noise ratio of 1, an averaged laser power of 10-mW and an averaging time of 5-min. The calibration accuracies (1σ) are ±17% for OH and ±18% for HO2 using the water-vapor photolysis/O2 actinometry calibration technique. OH and HO2 concentrations were successfully measured at an urban site in Mexico City, with observed concentrations comparable to those measured in other polluted environments. Enhanced levels of OH and HO2 radicals were observed on several days between 09:30–11:00 a.m. and suggest an intense photochemistry during morning hours that may be due to elevated sources of HOx (OH+HO2) and a fast cycling between the radicals under the high NOx (NO+NO2) conditions of the MCMA.

scholarly journals Laser-induced fluorescence-based detection of atmospheric nitrogen dioxide and comparison of different techniques during the PARADE 2011 field campaign

2019 ◽  
Vol 12 (3) ◽  
pp. 1461-1481 ◽  
Author(s):  
Umar Javed ◽  
Dagmar Kubistin ◽  
Monica Martinez ◽  
Jan Pollmann ◽  
Markus Rudolf ◽  
...  
Keyword(s):  
Nitrogen Dioxide ◽  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Laser Induced Fluorescence ◽  
Field Campaign ◽  
Accuracy And Precision ◽  
New Instrument ◽  
Laser Pulse Repetition Rate ◽  
Set Up

Abstract. GANDALF (Gas Analyzer for Nitrogen Dioxide Applying Laser-induced Fluorescence), a new instrument for the detection of nitrogen dioxide based on the laser-induced fluorescence (LIF) technique, is presented in this paper. GANDALF is designed for ground-based and airborne deployment with a robust calibration system. In the current set-up, it uses a multi-mode diode laser (447–450 nm) and performs in situ, continuous, and autonomous measurements with a laser pulse repetition rate of 5 MHz. The performance of GANDALF was tested during the summer of year 2011 (15 August–10 September) in a field experiment at Kleiner Feldberg, Germany. The location is within a forested region with an urban influence, where NOx levels were between 0.12 and 22 parts per billion by volume (ppb). Based on the field results, the limit of detection is estimated at 5–10 parts per trillion by volume (ppt) in 60 s at a signal-to-noise ratio (SNR) of 2. The overall accuracy and precision of the instrument are better than 5 % (1σ) and 0.5 %+3 ppt (1σ min−1), respectively. A comparison of nitrogen dioxide measurements based on several techniques during the field campaign PARADE 2011 is presented to explore methodic differences.

scholarly journals Laser induced fluorescence based detection of atmospheric nitrogen dioxide and comparison of different techniques during the PARADE 2011 field campaign

2018 ◽  
Author(s):  
Umar Javed ◽  
Dagmar Kubistin ◽  
Monica Martinez ◽  
Jan Pollmann ◽  
Markus Rudolf ◽  
...  
Keyword(s):  
Nitrogen Dioxide ◽  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Laser Induced Fluorescence ◽  
Field Campaign ◽  
Accuracy And Precision ◽  
New Instrument ◽  
Laser Pulse Repetition Rate ◽  
Multi Mode

Abstract. GANDALF (Gas Analyzer for Nitrogen Dioxide Applying Laser-induced Fluorescence), a new instrument for the detection of nitrogen dioxide based on the laser-induced fluorescence (LIF) technique, is presented in this paper. GANDALF is designed for ground based and air-borne deployment with a robust calibration system. In the current setup, it uses a multi-mode diode laser (447–450 nm) and performs in situ, continuous, and autonomous measurements with a laser pulse repetition rate of 5 MHz. The performance of GANDALF was tested during the field experiment at a forested location with urban influence where NOx levels were between 0.12 and 22 parts per billion by volume (ppbv). Based on the field results, the limit of detection is estimated at 5–10 parts per trillion by volume (pptv) in 60 s at a signal to noise ratio (SNR) of 2. The overall accuracy and precision of the instrument are better than 5 % (1 σ) and 0.5 % + 3 pptv (1 σ min−1), respectively. A comparison of nitrogen dioxide measurements based on several techniques during the field campaign is presented to explore methodic differences.

scholarly journals The Portable Ice Nucleation Experiment (PINE): a new online instrument for laboratory studies and automated long-term field observations of ice-nucleating particles

2021 ◽  
Vol 14 (2) ◽  
pp. 1143-1166
Author(s):  
Ottmar Möhler ◽  
Michael Adams ◽  
Larissa Lacher ◽  
Franziska Vogel ◽  
Jens Nadolny ◽  
...  
Keyword(s):  
Pure Water ◽  
Full Range ◽  
Field Measurements ◽  
Ice Nucleation ◽  
Spatial And Temporal Variation ◽  
Expansion Chamber ◽  
Predictive Capacity ◽  
Field Campaign ◽  
New Instrument ◽  
Term Field

Abstract. Atmospheric ice-nucleating particles (INPs) play an important role in determining the phase of clouds, which affects their albedo and lifetime. A lack of data on the spatial and temporal variation of INPs around the globe limits our predictive capacity and understanding of clouds containing ice. Automated instrumentation that can robustly measure INP concentrations across the full range of tropospheric temperatures is needed in order to address this knowledge gap. In this study, we demonstrate the functionality and capacity of the new Portable Ice Nucleation Experiment (PINE) to study ice nucleation processes and to measure INP concentrations under conditions pertinent for mixed-phase clouds, with temperatures from about −10 to about −40 ∘C. PINE is a cloud expansion chamber which avoids frost formation on the cold walls and thereby omits frost fragmentation and related background ice signals during the operation. The development, working principle and treatment of data for the PINE instrument is discussed in detail. We present laboratory-based tests where PINE measurements were compared with those from the established AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber. Within experimental uncertainties, PINE agreed with AIDA for homogeneous freezing of pure water droplets and the immersion freezing activity of mineral aerosols. Results from a first field campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) observatory in Oklahoma, USA, from 1 October to 14 November 2019 with the latest PINE design (a commercially available PINE chamber) are also shown, demonstrating PINE's ability to make automated field measurements of INP concentrations at a time resolution of about 8 min with continuous temperature scans for INP measurements between −10 and −30 ∘C. During this field campaign, PINE was continuously operated for 45 d in a fully automated and semi-autonomous way, demonstrating the capability of this new instrument to also be used for longer-term field measurements and INP monitoring activities in observatories.

scholarly journals The portable ice nucleation experiment PINE: a new online instrument for laboratory studies and automated long-term field observations of ice-nucleating particles

2020 ◽  
Author(s):  
Ottmar Möhler ◽  
Michael Adams ◽  
Larissa Lacher ◽  
Franziska Vogel ◽  
Jens Nadolny ◽  
...  
Keyword(s):  
Pure Water ◽  
Full Range ◽  
Field Measurements ◽  
Ice Nucleation ◽  
Spatial And Temporal Variation ◽  
High Time Resolution ◽  
Expansion Chamber ◽  
Field Campaign ◽  
New Instrument ◽  
Term Field

Abstract. Atmospheric ice-nucleating particles (INP) play an important role in determining the phase of clouds, which affects their albedo and lifetime. A lack of data on the spatial and temporal variation of INPs around the globe limits our predictive capacity and understanding of clouds containing ice. Automated instrumentation that can robustly measure INP concentrations across the full range of tropospheric temperatures is needed in order to address this knowledge gap. In this study, we demonstrate the functionality and capacity of the new Portable Ice Nucleation Experiment (PINE) to study ice nucleation processes and to measure INP concentrations under conditions pertinent for mixed-phase clouds, with temperatures from about −10 °C to about −38 °C. PINE is a cloud expansion chamber which avoids frost formation on the cold walls, and thereby omits frost fragmentation and related background ice signals during the operation. The development, working principle, and treatment of data for the PINE instrument is discussed in detail. We present extensive laboratory based tests where PINE measurements were compared with those from the established AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber. The results show good agreement of PINE with AIDA for homogeneous freezing of pure water droplets and the immersion freezing activity of mineral aerosols. Results from a first field campaign conducted at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) observatory in Oklahoma, USA, from October 1 to November 14, 2019 with the latest PINE design (a commercially available PINE chamber) are also shown, demonstrating PINE’s ability to make automated field measurements of INP concentrations at high time resolution of about 8 minutes with continuous wall temperature scans between −5 and −35 °C. During this field campaign, PINE was continuously operated for 45 days in a fully automated and semi-autonomous way, demonstrating the capability of this new instrument to be also used for longer term field measurements and INP monitoring activities in observatories.

scholarly journals Distance scaling method for accurate prediction of slowly varying magnetic fields in satellite missions

2016 ◽  
Vol 5 (2) ◽  
pp. 281-288 ◽  
Author(s):  
Panagiotis P. Zacharias ◽  
Elpida G. Chatzineofytou ◽  
Sotirios T. Spantideas ◽  
Christos N. Capsalis
Keyword(s):  
Signal To Noise Ratio ◽  
Near Field ◽  
Magnetic Behavior ◽  
Field Measurements ◽  
High Signal ◽  
Signal To Noise ◽  
Scaling Method ◽  
Magnetic Signature ◽  
The Magnetic Field

Abstract. In the present work, the determination of the magnetic behavior of localized magnetic sources from near-field measurements is examined. The distance power law of the magnetic field fall-off is used in various cases to accurately predict the magnetic signature of an equipment under test (EUT) consisting of multiple alternating current (AC) magnetic sources. Therefore, parameters concerning the location of the observation points (magnetometers) are studied towards this scope. The results clearly show that these parameters are independent of the EUT's size and layout. Additionally, the techniques developed in the present study enable the placing of the magnetometers close to the EUT, thus achieving high signal-to-noise ratio (SNR). Finally, the proposed method is verified by real measurements, using a mobile phone as an EUT.

scholarly journals Sources and transformations of particle-bound polycyclic aromatic hydrocarbons in Mexico City

2005 ◽  
Vol 5 (6) ◽  
pp. 12741-12773 ◽  
Author(s):  
L. C. Marr ◽  
K. Dzepina ◽  
J. L. Jimenez ◽  
F. Reisen ◽  
H. L. Bethel ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Mexico City ◽  
Aromatic Hydrocarbons ◽  
Heterogeneous Reactions ◽  
Field Campaign ◽  
Aerosol Mass ◽  
Aerosol Mass Spectrometry ◽  
Polycyclic Aromatic ◽  
First Time

Abstract. Understanding sources, concentrations, and transformation of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere is important because of their potent mutagenicity and carcinogenicity. The measurement of particle-bound PAHs by three different methods during the Mexico City Metropolitan Area field campaign in April 2003 presents a unique opportunity for characterization of these compounds and assessment of the methods. The three methods are (1) collection and analysis of bulk samples for time-integrated gas- and particle-phase speciation by gas chromatography/mass spectrometry; (2) aerosol photoionization for fast detection of PAHs on particles' surfaces; and (3) aerosol mass spectrometry for fast analysis of size and chemical composition. This research represents the first time aerosol mass spectrometry has been used to measure ambient PAH concentrations and the first time that fast, real-time methods have been used to quantify PAHs alongside traditional filter-based measurements in an extended field campaign. Speciated PAH measurements suggest that motor vehicles and garbage and wood burning are important sources in Mexico City. The diurnal concentration patterns captured by aerosol photoionization and aerosol mass spectrometry are generally consistent. Ambient concentrations typically peak at ~110 ng m−3 during the morning rush hour and rapidly decay due to changes in source activity patterns and dilution as the boundary layer rises, although surface-bound PAH concentrations decay faster. The more rapid decrease in surface versus bulk PAH concentrations during the late morning suggests that freshly emitted combustion-related particles are quickly coated by secondary aerosol material in Mexico City's atmosphere and may also be transformed by heterogeneous reactions.

scholarly journals In situ measurements of speciated atmospheric mercury and the identification of source regions in the Mexico City Metropolitan Area

2009 ◽  
Vol 9 (1) ◽  
pp. 207-220 ◽  
Author(s):  
A. P. Rutter ◽  
D. C. Snyder ◽  
E. A. Stone ◽  
J. J. Schauer ◽  
R. Gonzalez-Abraham ◽  
...  
Keyword(s):  
Point Source ◽  
Mexico City ◽  
Metropolitan Area ◽  
Atmospheric Mercury ◽  
Point Sources ◽  
Rural Site ◽  
Urban Site ◽  
Trajectory Data ◽  
Source Regions ◽  
Rural Sites

Abstract. In order to expand the currently limited understanding of atmospheric mercury source-receptor relationships in the Mexico City Metropolitan Area, real time measurements of atmospheric mercury were made at a downtown urban site, and a rural site on the outskirts of Mexico City, during March 2006. Numerous short-lived increases in particulate mercury (PHg) and reactive gaseous mercury (RGM) concentrations were observed at the urban site during the 17 day study, and less frequent increases in gaseous elemental mercury (GEM) concentrations were measured at both the urban and rural sites. The episodic increases observed were attributed to plume impacts from industrial point source emissions in and around Mexico City. Average concentrations and standard deviations measured during the study were as follows: i) urban site; PHg=187±300 pg m−3, RGM=62±64 pg m−3, GEM=7.2±4.8 ng m−3, and; ii) rural site; GEM=5.0±2.8 ng m−3. Several source regions of atmospheric mercury to the urban and rural sites were determined using Concentration Field Analysis, in which atmospheric mercury measurements were combined with back trajectory data to determine source regions. Only some source regions correlated to mercury emission sources listed in the Federal Pollutant Release and Transfer Register, leaving the rest unaccounted for. Contributions of anthropogenic mercury point sources in and around Mexico City to concentration averages measured at the urban site during the study were estimated to be: 93±3% of reactive mercury (PHg and RGM), and; 81±0.4% of GEM. Point source contributions to GEM measured at the rural site were 72±1%. GEM and reactive mercury (PHg+RGM) were not found to correlate with biomass burning at either of the measurement sites.

scholarly journals An automated online instrument to quantify aerosol-bound reactive oxygen species (ROS) for ambient measurement and health-relevant aerosol studies

2016 ◽  
Vol 9 (10) ◽  
pp. 4891-4900 ◽  
Author(s):  
Francis P. H. Wragg ◽  
Stephen J. Fuller ◽  
Ray Freshwater ◽  
David C. Green ◽  
Frank J. Kelly ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Dynamic Range ◽  
Measurement Techniques ◽  
Reactive Oxygen ◽  
Fast Response ◽  
Urban Site ◽  
Aerosol Sampling ◽  
Oxygen Species ◽  
Toxicological Studies ◽  
New Instrument

Abstract. The adverse health effects associated with ambient aerosol particles have been well documented, but it is still unclear which aerosol properties are most important for their negative health impact. Some studies suggest the oxidative effects of particle-bound reactive oxygen species (ROS) are potential major contributors to the toxicity of particles. Traditional ROS measurement techniques are labour-intensive, give poor temporal resolution and generally have significant delays between aerosol sampling and ROS analysis. However, many oxidising particle components are reactive and thus potentially short-lived. Thus, a technique to quantify particle-bound ROS online would be beneficial to quantify also the short-lived ROS components. We introduce a new portable instrument to allow online, continuous measurement of particle-bound ROS using a chemical assay of 2′7′-dichlorofluorescein (DCFH) with horseradish peroxidase (HRP), via fluorescence spectroscopy. All components of the new instrument are attached to a containing shell, resulting in a compact system capable of automated continuous field deployment over many hours or days. From laboratory measurements, the instrument was found to have a detection limit of ∼  4 nmol [H2O2] equivalents per cubic metre (m3) air, a dynamic range up to at least ∼  2000 nmol [H2O2] equivalents per m3 air and a time resolution of ≤  12 min. The instrument allows for ∼  16 h automated measurement if unattended and shows a fast response to changes in concentrations of laboratory-generated oxidised organic aerosol. The instrument was deployed at an urban site in London, and particulate ROS levels of up to 24 nmol [H2O2] equivalents per m3 air were detected with PM2.5 concentrations up to 28 µg m−3. The new and portable Online Particle-bound ROS Instrument (OPROSI) allows fast-response quantification; this is important due to the potentially short-lived nature of particle-bound ROS as well as fast-changing atmospheric conditions, especially in urban environments. The instrument design allows for automated operation and extended field operation with twice-daily presence of an operator. As well as having sensitivity suitable for ambient level measurement, the instrument is also suitable at concentrations such as those required for laboratory and chamber toxicological studies.

Sign in / Sign up

Export Citation Format

Share Document