scholarly journals Hydroxyl radicals in the tropical troposphere over the Suriname rainforest: airborne measurements

2010 ◽  
Vol 10 (8) ◽  
pp. 3759-3773 ◽  
Author(s):  
M. Martinez ◽  
H. Harder ◽  
D. Kubistin ◽  
M. Rudolf ◽  
H. Bozem ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Tropical Rainforest ◽  
Measurement Unit ◽  
Hydrocarbon Emissions ◽  
Sources And Sinks ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Photolysis Frequencies ◽  
Calibration Methods ◽  
Measurement Results

Abstract. Direct measurements of OH and HO2 over a tropical rainforest were made for the first time during the GABRIEL campaign in October 2005, deploying the custom-built HORUS instrument (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy), adapted to fly in a Learjet wingpod. Biogenic hydrocarbon emissions were expected to strongly reduce the OH and HO2 mixing ratios as the air is transported from the ocean over the forest. However, surprisingly high mixing ratios of both OH and HO2 were encountered in the boundary layer over the rainforest. The HORUS instrumentation and calibration methods are described in detail and the measurement results obtained are discussed. The extensive dataset collected during GABRIEL, including measurements of many other trace gases and photolysis frequencies, has been used to quantify the main sources and sinks of OH. Comparison of these measurement-derived formation and loss rates of OH indicates strong previously overlooked recycling of OH in the boundary layer over the tropical rainforest, occurring in chorus with isoprene emission.

scholarly journals Hydroxyl radicals in the tropical troposphere over the Suriname rainforest: airborne measurements

2008 ◽  
Vol 8 (4) ◽  
pp. 15491-15536 ◽  
Author(s):  
M. Martinez ◽  
H. Harder ◽  
D. Kubistin ◽  
M. Rudolf ◽  
H. Bozem ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Tropical Rainforest ◽  
Measurement Unit ◽  
Hydrocarbon Emissions ◽  
Sources And Sinks ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Photolysis Frequencies ◽  
Calibration Methods ◽  
Measurement Results

Abstract. Direct measurements of OH and HO2 over a tropical rainforest were made for the first time during the GABRIEL campaign in October 2005, deploying the custom-built HORUS instrument (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy), adapted to fly in a Learjet wingpod. Biogenic hydrocarbon emissions were expected to strongly reduce the OH and HO2 mixing ratios as the air is transported from the ocean over the forest. However, surprisingly high mixing ratios of both OH and HO2 were encountered in the boundary layer over the rainforest. The HORUS instrumentation and calibration methods are described in detail and the measurement results obtained are discussed. The extensive dataset collected during GABRIEL, including measurements of many other trace gases and photolysis frequencies, has been used to quantify the main sources and sinks of OH. Comparison of these measurement-derived formation and loss rates of OH indicates strong previously overlooked recycling of OH in the boundary layer over the tropical rainforest, occurring in chorus with isoprene emission.

scholarly journals HO<sub>x</sub> measurements in the summertime upper troposphere over Europe: a comparison of observations to a box model and a 3-D model

2012 ◽  
Vol 12 (11) ◽  
pp. 30619-30660 ◽  
Author(s):  
E. Regelin ◽  
H. Harder ◽  
M. Martinez ◽  
D. Kubistin ◽  
C. Tatum Ernest ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Circulation Model ◽  
Box Model ◽  
Measurement Unit ◽  
Data Set ◽  
Upper Troposphere ◽  
Sources And Sinks ◽  
Airborne Measurements ◽  
Mixing Ratios

Abstract. In-situ airborne measurements of OH and HO2 with the HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy) instrument were performed in the summertime upper troposphere across Europe during the HOOVER 2 (HOx OVer EuRope) campaign in July 2007. Complementary measurements of trace gas species and photolysis frequencies were conducted to obtain a broad data set, which has been used to quantify the significant HOx sources and sinks. In this study we compare the in-situ measurement of OH and HO2 with simulated mixing ratios from the constrained box model CAABA/MECCA (Chemistry As A Box Model Application/Module Efficiently Calculating the Chemistry of the Atmosphere), and the global circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry Model). The constrained box model reproduces the observed OH and HO2 mixing ratios with better agreement (obs/mod median 98% OH, 96% HO2) than the global model (median 76% OH, 59% HO2). The observations and the computed HOx sources and sinks are used to identify deviations between the models and their impacts on the calculated HOx budget.

scholarly journals HOx measurements in the summertime upper troposphere over Europe: a comparison of observations to a box model and a 3-D model

2013 ◽  
Vol 13 (21) ◽  
pp. 10703-10720 ◽  
Author(s):  
E. Regelin ◽  
H. Harder ◽  
M. Martinez ◽  
D. Kubistin ◽  
C. Tatum Ernest ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Circulation Model ◽  
Box Model ◽  
Measurement Unit ◽  
Data Set ◽  
Upper Troposphere ◽  
Sources And Sinks ◽  
Airborne Measurements ◽  
Mixing Ratios

Abstract. In situ airborne measurements of OH and HO2 with the HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy) instrument were performed in the summertime upper troposphere across Europe during the HOOVER 2 (HOx OVer EuRope) campaign in July 2007. Complementary measurements of trace gas species and photolysis frequencies were conducted to obtain a broad data set, which has been used to quantify the significant HOx sources and sinks. In this study we compare the in situ measurement of OH and HO2 with simulated mixing ratios from the constrained box model CAABA/MECCA (Chemistry As A Box Model Application/Module Efficiently Calculating the Chemistry of the Atmosphere), and the global circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry Model). The constrained box model reproduces the observed OH and HO2 mixing ratios with better agreement (obs/mod median 98% OH, 96% HO2) than the global model (median 76% OH, 59% HO2). The observations and the computed HOx sources and sinks are used to identify deviations between the models and their impacts on the calculated HOx budget.

Aircraft measurements of nitrous acid in excess of model predictions in the boundary layer and free troposphere

2020 ◽  
Author(s):  
Benjamin Schreiner ◽  
Klaus Pfeilsticker ◽  
Flora Kluge ◽  
Meike Rotermund ◽  
Andreas Zahn ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Optical Absorption Spectroscopy ◽  
Free Troposphere ◽  
Aerosol Composition ◽  
Transport And Transformation ◽  
Air Masses ◽  
Airborne Measurements ◽  
Photolysis Frequencies ◽  
Model Predictions

&lt;p&gt;Middle and long-term &amp;#160;photo-chemical effects of local and regional pollution are not well quantified and are an area of active study. NO&lt;sub&gt;x&lt;/sub&gt; (here defined as NO, NO&lt;sub&gt;2&lt;/sub&gt;, and HONO) is a regional pollutant, which influences atmospheric oxidation capacity and ozone formation. Airborne measurements of atmospheric trace gases from the HALO (High Altitude Long Range) aircraft, particularly of NO, NO&lt;sub&gt;2&lt;/sub&gt;, and HONO were performed as part of the EMeRGe (Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global Scales) campaign over continental Europe and southeast Asia in July 2017 and April 2018, respectively. NO (and NO&lt;sub&gt;Y&lt;/sub&gt;), O&lt;sub&gt;3&lt;/sub&gt;, and the photolysis frequencies of NO&lt;sub&gt;2&lt;/sub&gt; and HONO were measured in-situ. NO&lt;sub&gt;2&lt;/sub&gt; and HONO were inferred from Limb measurements of the mini-DOAS (Differential Optical Absorption Spectroscopy) instrument, using the novel scaling method (H&amp;#252;neke et al., 2017). These measurements were compared with simulations of the MECO/EMAC models. In relatively polluted air-masses in the boundary layer and free troposphere, HONO measured in excess of model predictions (and previous measurements) suggests an in-situ formation and a significant source of OH as well as a pathway for re-noxification. Aerosol composition simultaneously measured &amp;#160;by the C-Tof-AMS instrument may reveal potential reaction mechanisms to explain the discrepancy.&amp;#160;&lt;/p&gt;

scholarly journals Lightning-produced NO<sub>x</sub> over Brazil during TROCCINOX: airborne measurements in tropical and subtropical thunderstorms and the importance of mesoscale convective systems

2007 ◽  
Vol 7 (11) ◽  
pp. 2987-3013 ◽  
Author(s):  
H. Huntrieser ◽  
H. Schlager ◽  
A. Roiger ◽  
M. Lichtenstern ◽  
U. Schumann ◽  
...  
Keyword(s):  
Boundary Layer ◽  
South Atlantic ◽  
Convective System ◽  
The South ◽  
Air Masses ◽  
Upper Troposphere ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Mesoscale Convective ◽  
Upward Transport

Abstract. During the TROCCINOX field experiments in February–March 2004 and February 2005, airborne in situ measurements of NO, NOy, CO, and O3 mixing ratios and the J(NO2) photolysis rate were carried out in the anvil outflow of thunderstorms over southern Brazil. Both tropical and subtropical thunderstorms were investigated, depending on the location of the South Atlantic convergence zone. Tropical air masses were discriminated from subtropical ones according to the higher equivalent potential temperature (Θe) in the lower and mid troposphere, the higher CO mixing ratio in the mid troposphere, and the lower wind velocity in the upper troposphere within the Bolivian High (north of the subtropical jet stream). During thunderstorm anvil penetrations, typically at 20–40 km horizontal scales, NOx mixing ratios were distinctly enhanced and the absolute mixing ratios varied between 0.2–1.6 nmol mol−1 on average. This enhancement was mainly attributed to NOx production by lightning and partly due to upward transport from the NOx-richer boundary layer. In addition, CO mixing ratios were occasionally enhanced, indicating upward transport from the boundary layer. For the first time, the composition of the anvil outflow from a large, long-lived mesoscale convective system (MCS) advected from northern Argentina and Uruguay was investigated in more detail. Over a horizontal scale of about 400 km, NOx, CO and O3 absolute mixing ratios were significantly enhanced in these air masses in the range of 0.6–1.1, 110–140 and 60–70 nmol mol−1, respectively. Analyses from trace gas correlations and a Lagrangian particle dispersion model indicate that polluted air masses, probably from the Buenos Aires urban area and from biomass burning regions, were uplifted by the MCS. Ozone was distinctly enhanced in the aged MCS outflow, due to photochemical production and entrainment of O3-rich air masses from the upper troposphere – lower stratosphere region. The aged MCS outflow was transported to the north, ascended and circulated, driven by the Bolivian High over the Amazon basin. In the observed case, the O3-rich MCS outflow remained over the continent and did not contribute to the South Atlantic ozone maximum.

scholarly journals Lightning-produced NO<sub>x</sub> over Brazil during TROCCINOX: Airborne measurements in tropical and subtropical thunderstorms and the importance of mesoscale convective systems

2007 ◽  
Vol 7 (1) ◽  
pp. 2561-2621 ◽  
Author(s):  
H. Huntrieser ◽  
H. Schlager ◽  
A. Roiger ◽  
M. Lichtenstern ◽  
U. Schumann ◽  
...  
Keyword(s):  
Boundary Layer ◽  
South Atlantic ◽  
Convective System ◽  
The South ◽  
Air Masses ◽  
Upper Troposphere ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Mesoscale Convective ◽  
Upward Transport

Abstract. During the TROCCINOX field experiments in February–March 2004 and February 2005, airborne in situ measurements of NO, NOy, CO, and O3 mixing ratios and the J(NO2) photolysis rate were carried out in the anvil outflow of thunderstorms over southern Brazil. Both tropical and subtropical thunderstorms were investigated, depending on the location of the South Atlantic convergence zone. Tropical air masses were discriminated from subtropical ones according to the higher equivalent potential temperature (Θe) in the lower and mid troposphere, the higher CO mixing ratio in the mid troposphere, and the lower wind velocity and proper wind direction in the upper troposphere. During thunderstorm anvil penetrations, typically at 20–40 km horizontal scales, NOx mixing ratios were on average enhanced by 0.2–1.6 nmol mol−1. This enhancement was mainly attributed to NOx production by lightning and partly due to upward transport from the NOx-richer boundary layer. In addition, CO mixing ratios were occasionally enhanced, indicating upward transport from the boundary layer. For the first time, the composition of the anvil outflow from a large, long-lived mesoscale convective system (MCS) advected from northern Argentina and Uruguay was investigated in more detail. Over a horizontal scale of about 400 km, NOx, CO and O3 mixing ratios were significantly enhanced in these air masses in the range of 0.6–1.1, 110–140 and 60–70 nmol mol−1, respectively. Analyses from trace gas correlations and a Lagrangian particle dispersion model indicate that polluted air masses, probably from the Buenos Aires urban area and from biomass burning regions, were uplifted by the MCS. Ozone was distinctly enhanced in the aged MCS outflow, due to photochemical production and entrainment of O3-rich air masses from the upper troposphere – lower stratosphere region. The aged MCS outflow was transported to the north, ascended and circulated, driven by the Bolivian High over the Amazon basin. In the observed case, the O3-rich MCS outflow remained over the continent and did not contribute to the South Atlantic ozone maximum.

scholarly journals Atmospheric bromoform at Mace Head, Ireland: seasonality and evidence for a peatland source

2005 ◽  
Vol 5 (11) ◽  
pp. 2927-2934 ◽  
Author(s):  
L. J. Carpenter ◽  
D. J. Wevill ◽  
S. O'Doherty ◽  
G. Spain ◽  
P. G. Simmonds
Keyword(s):  
Boundary Layer ◽  
Wind Direction ◽  
Marine Boundary Layer ◽  
Land Breeze ◽  
Peat Bogs ◽  
Mixing Ratios ◽  
The North ◽  
Prevailing Wind Direction ◽  
Atmospheric Observations ◽  
Summer Minimum

Abstract. In situ atmospheric observations of bromoform (CHBr3) made over a 2.5 year period at Mace Head, Ireland from May 2001- Dec 2003, including during the NAMBLEX (North Atlantic Marine Boundary Layer Experiment) campaign, show broad maxima from spring until autumn and winter minima, with mixing ratios of 5.3+1.0 pptv (mid March - mid October) and 1.8+0.8 pptv (December-February). This indicates that, unlike CHCl3, which has a summer minimum and winter maximum at Mace Head, local biological sources of CHBr3 have a greater influence on the atmospheric data than photochemical decay during long-range transport. The emission sources are predominantly macroalgal, but we find evidence for a small terrestrial flux from peatland ecosystems, which so far has not been accounted for in the CHBr3 budget. Sharp increases in CHCl3 and CHBr3 concentrations and decreases in O3 concentrations occurred at night when the wind direction switched from an ocean- to a land-based sector (land breeze) and the wind speed dropped to below 5 ms-1. These observations infer a shallow atmospheric boundary layer with increased O3 deposition and concentration of local emissions of both CHCl3 and CHBr3. The ratio of ΔCHCl3/ΔCHBr3 varied strongly according to the prevailing wind direction; from 0.60+0.15 in south-easterly (100-170° and northerly (340-20°) air to 2.5+0.4 in north-easterly (40-70°) air. Of these land-sectors, the south-easterly air masses are likely to be strongly influenced by macroalgal beds along the coast and the emission ratios probably reflect those from seaweeds in addition to land sources. The north-easterly airmasses however had an immediate fetch inland, which locally is comprised of coastal peatland ecosystems (peat bogs and coastal conifer plantations), previously identified as being strong sources of atmospheric CHCl3 under these conditions. Although we cannot entirely rule out other local land or coastal sources, our observations also suggest peatland ecosystem emissions of CHBr3. We use correlations between CHCl3 and CHBr3 during the north-easterly land breeze events in conjunction with previous estimates of local wetland CHCl3 release to tentatively deduce a global wetland CHBr3 source of 20.4(0.4-948) Gg yr-1, which is approximately 7% of the total global source.

scholarly journals Airborne determination of the temporo-spatial distribution of benzene, toluene, nitrogen oxides and ozone in the boundary layer across Greater London, UK

2015 ◽  
Vol 15 (9) ◽  
pp. 5083-5097 ◽  
Author(s):  
M. D. Shaw ◽  
J. D. Lee ◽  
B. Davison ◽  
A. Vaughan ◽  
R. M. Purvis ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Nitrogen Oxides ◽  
Linear Regression Analysis ◽  
Proton Transfer Reaction ◽  
Mixing Ratios ◽  
Spatially Resolved ◽  
Dual Channel ◽  
Benzene Toluene

Abstract. Highly spatially resolved mixing ratios of benzene and toluene, nitrogen oxides (NOx) and ozone (O3) were measured in the atmospheric boundary layer above Greater London during the period 24 June to 9 July 2013 using a Dornier 228 aircraft. Toluene and benzene were determined in situ using a proton transfer reaction mass spectrometer (PTR-MS), NOx by dual-channel NOx chemiluminescence and O3 mixing ratios by UV absorption. Average mixing ratios observed over inner London at 360 ± 10 m a.g.l. were 0.20 ± 0.05, 0.28 ± 0.07, 13.2 ± 8.6, 21.0 ± 7.3 and 34.3 ± 15.2 ppbv for benzene, toluene, NO, NO2 and NOx respectively. Linear regression analysis between NO2, benzene and toluene mixing ratios yields a strong covariance, indicating that these compounds predominantly share the same or co-located sources within the city. Average mixing ratios measured at 360 ± 10 m a.g.l. over outer London were always lower than over inner London. Where traffic densities were highest, the toluene / benzene (T / B) concentration ratios were highest (average of 1.8 ± 0.5 ppbv ppbv-1), indicative of strong local sources. Daytime maxima in NOx, benzene and toluene mixing ratios were observed in the morning (~ 40 ppbv NOx, ~ 350 pptv toluene and ~ 200 pptv benzene) and in the mid-afternoon for ozone (~ 40 ppbv O3), all at 360 ± 10 m a.g.l.

An Impedance Sensor of Water Cut with Three Electrodes and Relative Analysis on Experiment Results

2021 ◽  
Author(s):  
Chuan Yu ◽  
Qinghai Yang ◽  
Songbo Wei ◽  
Ming Li ◽  
Tao Fu
Keyword(s):  
Single Layer ◽  
High Water ◽  
Sensor Calibration ◽  
Mixing Ratios ◽  
Margin Of Error ◽  
Measurement Results ◽  
Oil Water ◽  
High Water Cut ◽  
Water Cut ◽  
Impedance Sensor

Abstract Single-layer water cut measurement is of great significance for identifying and shutting off the unwanted water, analyzing oil remained and optimizing production. Currently, however, only the water cut of multilayer mixture can be measured by testing samples taken from wellhead, a way which is widely used in oilfields. That of single-layer fluid cannot be determined yet To address the problem, this paper puts forward a new impedance sensor that offers long-term online monitoring of single-layer water cut. This sensor is based on the different electrical conductivity of oil and water. It has two layers. The inner one contains three electrodes - two at both sides sending sinusoidal excitation signals and one at the middle receiving signals that have been attenuated by the water-oil medium. With the Maxwell's model of oil-water mixed fluid, the receiver then can measure the water cut online. The outer layer of the sensor is made of PEEK, an insulative protection. In front of the electrodes lies a static mixer which makes the measurement more accurate by fully blending the two media when they flow through the electrodes. Laboratory tests are carried out with the prototype of the sensor at various oil-water mixing ratios, fluid flow rates, and temperatures. Results show that the average margin of error is within ± 3%. Higher accuracy is seen when high water cut and flow rate enable oil globules to disperse more evenly and the space in between to get wider and the RMS error is less than 2%. If the water cut drops below 80%, the aggregation of the droplets will cause wild fluctuation and more errors in the measurement. In addition, the mineralization of the mixture directly changes its conductivity, which largely impacts the result. Meanwhile, temperature can influence the ionic movement intensity and then alter the conductivity of the medium. Therefore, in practice, the sensor calibration needs to be performed according to the range of medium salinity, and the temperature of the medium is collected in real time for temperature compensation. It is shown that after the adjustment, the water cut measurement results have higher accuracy and consistency. The impedance sensor can realize online water cut monitoring for a single-layer, indicated by tests. It is more suitable for the increasing high water cut oilfields in that it is more accurate as the water cut grows.

scholarly journals An aircraft gas chromatograph–mass spectrometer System for Organic Fast Identification Analysis (SOFIA): design, performance and a case study of Asian monsoon pollution outflow

2017 ◽  
Vol 10 (12) ◽  
pp. 5089-5105 ◽  
Author(s):  
Efstratios Bourtsoukidis ◽  
Frank Helleis ◽  
Laura Tomsche ◽  
Horst Fischer ◽  
Rolf Hofmann ◽  
...  
Keyword(s):  
Time Resolution ◽  
Asian Monsoon ◽  
Electrical Safety ◽  
Back Trajectory ◽  
Airborne Measurements ◽  
Mixing Ratios ◽  
Fast Identification ◽  
Chemistry Research ◽  
Identification Analysis

Abstract. Volatile organic compounds (VOCs) are important for global air quality and oxidation processes in the troposphere. In addition to ground-based measurements, the chemical evolution of such species during transport can be studied by performing in situ airborne measurements. Generally, aircraft instrumentation needs to be sensitive, robust and sample at higher frequency than ground-based systems while their construction must comply with rigorous mechanical and electrical safety standards. Here, we present a new System for Organic Fast Identification Analysis (SOFIA), which is a custom-built fast gas chromatography–mass spectrometry (GC-MS) system with a time resolution of 2–3 min and the ability to quantify atmospheric mixing ratios of halocarbons (e.g. chloromethanes), hydrocarbons (e.g isoprene), oxygenated VOCs (acetone, propanal, butanone) and aromatics (e.g. benzene, toluene) from sub-ppt to ppb levels. The relatively high time resolution is the result of a novel cryogenic pre-concentration unit which rapidly cools (∼ 6 °C s−1) the sample enrichment traps to −140 °C, and a new chromatographic oven designed for rapid cooling rates (∼ 30 °C s−1) and subsequent thermal stabilization. SOFIA was installed in the High Altitude and Long Range Research Aircraft (HALO) for the Oxidation Mechanism Observations (OMO) campaign in August 2015, aimed at investigating the Asian monsoon pollution outflow in the tropical upper troposphere. In addition to a comprehensive instrument characterization we present an example monsoon plume crossing flight as a case study to demonstrate the instrument capability. Hydrocarbon, halocarbon and oxygenated VOC data from SOFIA are compared with mixing ratios of carbon monoxide (CO) and methane (CH4), used to define the pollution plume. By using excess (ExMR) and normalized excess mixing ratios (NEMRs) the pollution could be attributed to two air masses of distinctly different origin, identified by back-trajectory analysis. This work endorses the use of SOFIA for aircraft operation and demonstrates the value of relatively high-frequency, multicomponent measurements in atmospheric chemistry research.

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