scholarly journals A Relaxed Eddy Accumulation (REA) LOPAP-System for Flux Measurements of Nitrous Acid (HONO)

2021 ◽  
Author(s):  
Lisa von der Heyden ◽  
Walter Wißdorf ◽  
Ralf Kurtenbach ◽  
Jörg Kleffmann
Keyword(s):  
Nitrous Acid ◽  
Formation Mechanisms ◽  
Minor Importance ◽  
Night Time ◽  
Field Campaign ◽  
Air Masses ◽  
Relaxed Eddy Accumulation ◽  
Photolysis Frequency ◽  
Ultrasonic Anemometer ◽  
Flux Measurements

Abstract. In the present study a Relaxed Eddy Accumulation (REA) system for the quantification of vertical fluxes of nitrous acid (HONO) was developed and tested. The system is based on a three-channel-LOPAP instrument, for which two channels are used for the updrafts and downdrafts, respectively, and a third one for the correction of chemical interferences. The instrument is coupled to a REA gas inlet, for which an ultrasonic anemometer controls two fast magnetic valves to probe the two channels of the LOPAP instrument depending on the vertical wind direction. A software (PyREA) was developed, which controls the valves and measurement cycles, which regularly alternates between REA-, zero- and parallel ambient measurements. In addition, the assignment of the updrafts and downdrafts to the physical LOPAP channels is periodically alternated, to correct for differences in the interferences of the different air masses. During the study, only small differences of the interferences were identified for the updrafts and downdrafts excluding significant errors when using only one interference channel. In laboratory experiments, high precision of the two channels and the independence of the dilution corrected HONO concentrations on the length of the valve switching periods were demonstrated. A field campaign was performed in order to test the new REA-LOPAP system at the TROPOS monitoring station in Melpitz, Germany. HONO fluxes in the range of −4·1013 molecules m−2 s−1 (deposition) to +1.0·1014 molecules m−2 s−1 (emission) were obtained. A typical diurnal variation of the HONO fluxes was observed with low, partly negative fluxes during night-time and higher positive fluxes around noon. After an intensive rain period the positive HONO emissions during daytime were continuously increasing, which was explained by the drying of the upper most ground surfaces. Similar to other campaigns, the highest correlation of the HONO flux was observed with the product of the NO2 photolysis frequency and the NO2 concentration (J(NO2)·[NO2]), which implies a HONO formation by photosensitized conversion of NO2 on organic surfaces, like e.g. humic acids. Other postulated HONO formation mechanisms are also discussed, but are ranked being of minor importance for the present field campaign.

scholarly journals ClOOCl photolysis at high solar zenith angles: analysis of the RECONCILE self-match flight

2011 ◽  
Vol 11 (7) ◽  
pp. 18901-18926 ◽  
Author(s):  
O. Sumińska-Ebersoldt ◽  
R. Lehmann ◽  
T. Wegner ◽  
J.-U. Grooß{} ◽  
E. Hösen ◽  
...  
Keyword(s):  
Cross Sections ◽  
Thermal Equilibrium ◽  
Wavelength Region ◽  
Recombination Reaction ◽  
Night Time ◽  
Air Masses ◽  
Photolysis Frequency ◽  
Atmospheric Observations ◽  
The One ◽  
Catalytic Cycles

Abstract. The photolysis frequency of dichlorine peroxide (ClOOCl) JClOOCl is a critical parameter in catalytic cycles destroying ozone in the polar stratosphere. In the atmospherically relevant wavelength region, published laboratory measurements of ClOOCl absorption cross sections and spectra are not in good agreement, resulting in significant discrepancies in JClOOCl. Previous investigations of the consistency with atmospheric observations of ClO and ClOOCl have focused on the photochemical equilibrium between ClOOCl formation and photolysis, and thus could only constrain the ratio of JClOOCl over the rate constant of the ClO recombination reaction krec. Here, we constrain the atmospherically effective JClOOCl independent of krec using ClO data sampled in the same air masses before and directly after sunrise. Over sunrise, when the ClO/ClOOCl system comes out of thermal equilibrium and the influence of the ClO recombination reaction is negligible, the rise in ClO concentration is significantly faster than expected from JClOOCl based on the absorption spectrum proposed by Pope et al. (2007), but does not warrant cross sections larger than recently published values by Papanastasiou et al. (2009). In particular, the existence of a significant ClOOCl absorption band longwards of 420 nm, is effectively ruled out by our observations. Additionally, the night-time ClO observations show that the ClO/ClOOCl thermal equilibrium constant can not be significantly higher than the one proposed by Plenge et al. (2005).

scholarly journals Tropospheric HONO Distribution and Chemistry in the Southeast U.S.

2018 ◽  
Author(s):  
Chunxiang Ye ◽  
Xianliang Zhou ◽  
Dennis Pu ◽  
Jochen Stutz ◽  
James Festa ◽  
...  
Keyword(s):  
Field Study ◽  
Ground Surface ◽  
Residual Layer ◽  
Formation Mechanisms ◽  
Oxides Of Nitrogen ◽  
Night Time ◽  
Air Masses ◽  
Measurement Results ◽  
Research Aircraft ◽  
Important Intermediate

Abstract. Here we report the measurement results of nitrous acid (HONO) and a suite of relevant parameters on the NCAR C-130 research aircraft in the Southeast U.S. during NOMADSS 2013 summer field study. Daytime HONO concentrations ranged from low parts per trillion by volume (pptv) in the free troposphere (FT) to mostly within 5–15 pptv in the background terrestrial air masses, and to up to 40 pptv in the industrial and urban plumes in the planetary boundary layer (PBL). There was no discernable vertical HONO distribution trend in the PBL above the lowest flight altitude of 300 m, indicating that the ground surface HONO source was not a significant contributor to the HONO budget in the measurement altitude between 300 m and 4.7 km. While there was a strong correlation between the concentrations of HONO and oxides of nitrogen (NOx = NO + NO2) (R2 = 0.52), the sum of all known NOx-related HONO formation mechanisms was found to account for less 20 % of the daytime HONO source in the background terrestrial air masses, due to the low level of NOx and surface area density of aerosol particles. Photolysis of particulate nitrate (pNO3) appeared to be the major daytime HONO source in the background terrestrial air masses, based on the measured pNO3 concentration and the median value of 2.0 × 10−4 s−1 for pNO3 photolysis rate constant determined in the laboratory using ambient aerosol samples collected during the field study. Within the power plant and industrial plumes encountered, daytime HONO was predominantly produced by secondary formation processes involving both NOx and pNO3 as precursors. While HONO was not a significant OH precursor compared to O3 under low NOx conditions in the air column, it was an important intermediate product of a photochemical renoxification process recycling nitric acid and nitrate back to NOx. Finally, the HONO / NOx ratio stayed relatively constant for several hours after sunset in the nocturnal residual layer, suggesting no significant night-time volume HONO source existed in the nocturnal residual layer and the nocturnal FT under background conditions.

scholarly journals Exploring the atmospheric chemistry of nitrous acid (HONO) at a rural site in Southern China

2012 ◽  
Vol 12 (3) ◽  
pp. 1497-1513 ◽  
Author(s):  
X. Li ◽  
T. Brauers ◽  
R. Häseler ◽  
B. Bohn ◽  
H. Fuchs ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Nitrous Acid ◽  
Southern China ◽  
Rural Site ◽  
Pearl River Delta Region ◽  
Additional Source ◽  
Mixing Ratios ◽  
Photolysis Frequency ◽  
The Pearl River

Abstract. We performed measurements of nitrous acid (HONO) during the PRIDE-PRD2006 campaign in the Pearl River Delta region 60 km north of Guangzhou, China, for 4 weeks in June 2006. HONO was measured by a LOPAP in-situ instrument which was setup in one of the campaign supersites along with a variety of instruments measuring hydroxyl radicals, trace gases, aerosols, and meteorological parameters. Maximum diurnal HONO mixing ratios of 1–5 ppb were observed during the nights. We found that the nighttime build-up of HONO can be attributed to the heterogeneous NO2 to HONO conversion on ground surfaces and the OH + NO reaction. In addition to elevated nighttime mixing ratios, measured noontime values of ≈200 ppt indicate the existence of a daytime source higher than the OH + NO→HONO reaction. Using the simultaneously recorded OH, NO, and HONO photolysis frequency, a daytime additional source strength of HONO (PM) was calculated to be 0.77 ppb h−1 on average. This value compares well to previous measurements in other environments. Our analysis of PM provides evidence that the photolysis of HNO3 adsorbed on ground surfaces contributes to the HONO formation.

Ammonia flux measurements above a corn canopy using relaxed eddy accumulation and a flux gradient system

2019 ◽  
Vol 264 ◽  
pp. 104-113 ◽  
Author(s):  
Andrew J. Nelson ◽  
Nebila Lichiheb ◽  
Sotiria Koloutsou-Vakakis ◽  
Mark J. Rood ◽  
Mark Heuer ◽  
...  
Keyword(s):  
Gradient System ◽  
Flux Gradient ◽  
Relaxed Eddy Accumulation ◽  
Flux Measurements ◽  
Ammonia Flux ◽  
Corn Canopy

scholarly journals Stable carbon and nitrogen isotope ratio in PM1 and size segregated aerosol particles over the Baltic Sea

2019 ◽  
Vol 59 (3) ◽  
Author(s):  
Inga Garbarienė ◽  
Vidmantas Remeikis ◽  
Agnë Mašalaitė ◽  
Andrius Garbaras ◽  
Tpmasz Petelski ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Size Range ◽  
Road Traffic ◽  
Aerosol Particles ◽  
Nitrogen Isotope ◽  
Total Carbon ◽  
Formation Mechanisms ◽  
The Baltic Sea ◽  
Air Masses ◽  
The Baltic

We analysed δ13C of total carbon (TC) and δ15N of total nitrogen (TN) in submicron (PM1) and size segregated aerosol particles (PM0.056–2.5) collected during a cruise in the Baltic Sea from 9 to 17 November 2012. PM1 were characterized by the highest δ13C (–26.4‰) and lowest δ15N (–0.2 and 0.8‰) values when air masses arrived from the southwest direction (Poland). The obtained δ13C values indicated that combined emissions of coal and diesel/gasoline combustion were the most likely sources of TC. The depleted δ15N values indicated that TN originated mainly from liquid fuel combustion (road traffic, shipping) during this period. The lowest δ13C and highest δ15N values were determined in PM1 samples during the western airflow when the air masses had no recent contact with land. The highest δ15N values were probably associated with chemical aging of nitrogenous species during long-range transport, the lowest δ13C values could be related to emissions from diesel/gasoline combustion, potentially from ship traffic. The δ13C analysis of size-segregated aerosol particles PM0.056–2.5 revealed that the lowest δ13C values were observed in the size range from 0.056 to 0.18 µm and gradual 13C enrichment occurred in the size range from 0.18 to 2.5 µm due to different sources or formation mechanisms of the aerosols.

scholarly journals Processing of biomass burning aerosol in the Eastern Mediterranean during summertime

2013 ◽  
Vol 13 (10) ◽  
pp. 25969-25999 ◽  
Author(s):  
A. Bougiatioti ◽  
I. Stavroulas ◽  
E. Kostenidou ◽  
P. Zarmpas ◽  
C. Theodosi ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Biomass Burning ◽  
Eastern Mediterranean ◽  
Late Summer ◽  
Organic Aerosol ◽  
High Temporal Resolution ◽  
Night Time ◽  
Air Masses ◽  
Aerosol Mass ◽  
Atmospheric Processing

Abstract. The aerosol chemical composition in air masses affected by wildfires from the Greek islands of Chios, Euboea and Andros, the Dalmatian Coast and Sicily, during late summer of 2012 was characterized at the remote background site of Finokalia, Crete. Air masses were transported several hundreds of kilometers, arriving at the measurement station after approximately half a day of transport, mostly during night-time. The chemical composition of the particulate matter was studied by different high temporal resolution instruments, including an Aerosol Chemical Speciation Monitor (ACSM) and a seven-wavelength aethalometer. Despite the large distance from emission and long atmospheric processing, a clear biomass burning organic aerosol (BBOA) profile containing characteristic markers is derived from BC measurements and Positive Matrix Factorization (PMF) analysis of the ACSM mass spectra. The ratio of fresh to aged BBOA decreases with increasing atmospheric processing time and BBOA components appear to be converted to oxygenated organic aerosol (OOA). Given that the smoke was mainly transported overnight, it appears that the processing can take place in the dark. These results show that a significant fraction of the BBOA loses its characteristic AMS signature and is transformed to OOA in less than a day. This implies that biomass burning can contribute almost half of the organic aerosol mass in the area during summertime.

scholarly journals Insights from mercury stable isotopes on terrestrial–atmosphere exchange of Hg(0) in the Arctic tundra

2019 ◽  
Vol 16 (20) ◽  
pp. 4051-4064 ◽  
Author(s):  
Martin Jiskra ◽  
Jeroen E. Sonke ◽  
Yannick Agnan ◽  
Detlev Helmig ◽  
Daniel Obrist
Keyword(s):  
Stable Isotope ◽  
Dominant Role ◽  
Arctic Tundra ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Night Time ◽  
Field Station ◽  
Terrestrial Atmosphere ◽  
Tundra Ecosystem ◽  
Flux Measurements

Abstract. The tundra plays a pivotal role in the Arctic mercury (Hg) cycle by storing atmospheric Hg deposition and shuttling it to the Arctic Ocean. A recent study revealed that 70 % of the atmospheric Hg deposition to the tundra occurs through gaseous elemental mercury (GEM or Hg(0)) uptake by vegetation and soils. Processes controlling land–atmosphere exchange of Hg(0) in the Arctic tundra are central, but remain understudied. Here, we combine Hg stable isotope analysis of Hg(0) in the atmosphere, interstitial snow air, and soil pore air, with Hg(0) flux measurements in a tundra ecosystem at Toolik Field Station in northern Alaska (USA). In the dark winter months, planetary boundary layer (PBL) conditions and Hg(0) concentrations were generally stable throughout the day and small Hg(0) net deposition occurred. In spring, halogen-induced atmospheric mercury depletion events (AMDEs) occurred, with the fast re-emission of Hg(0) after AMDEs resulting in net emission fluxes of Hg(0). During the short snow-free growing season in summer, vegetation uptake of atmospheric Hg(0) enhanced atmospheric Hg(0) net deposition to the Arctic tundra. At night, when PBL conditions were stable, ecosystem uptake of atmospheric Hg(0) led to a depletion of atmospheric Hg(0). The night-time decline of atmospheric Hg(0) was concomitant with a depletion of lighter Hg(0) isotopes in the atmospheric Hg pool. The enrichment factor, ε202Hgvegetationuptake=-4.2 ‰ (±1.0 ‰) was consistent with the preferential uptake of light Hg(0) isotopes by vegetation. Hg(0) flux measurements indicated a partial re-emission of Hg(0) during daytime, when solar radiation was strongest. Hg(0) concentrations in soil pore air were depleted relative to atmospheric Hg(0) concentrations, concomitant with an enrichment of lighter Hg(0) isotopes in the soil pore air, ε202Hgsoilair-atmosphere=-1.00 ‰ (±0.25 ‰) and E199Hgsoilair-atmosphere=0.07 ‰ (±0.04 ‰). These first Hg stable isotope measurements of Hg(0) in soil pore air are consistent with the fractionation previously observed during Hg(0) oxidation by natural humic acids, suggesting abiotic oxidation as a cause for observed soil Hg(0) uptake. The combination of Hg stable isotope fingerprints with Hg(0) flux measurements and PBL stability assessment confirmed a dominant role of Hg(0) uptake by vegetation in the terrestrial–atmosphere exchange of Hg(0) in the Arctic tundra.

Accuracy of the relaxed eddy-accumulation technique, evaluated using CO2 flux measurements

1993 ◽  
Vol 66 (4) ◽  
pp. 341-355 ◽  
Author(s):  
E. Pattey ◽  
R. L. Desjardins ◽  
P. Rochette
Keyword(s):  
Co2 Flux ◽  
Relaxed Eddy Accumulation ◽  
Flux Measurements

scholarly journals Characteristics of the NO-NO<sub>2</sub>-O<sub>3</sub> system in different chemical regimes during the MIRAGE-Mex field campaign

2008 ◽  
Vol 8 (1) ◽  
pp. 2275-2309 ◽  
Author(s):  
Z.-H. Shon ◽  
S. Madronich ◽  
S.-K. Song ◽  
F. M. Flocke ◽  
D. J. Knapp ◽  
...  
Keyword(s):  
Production Efficiency ◽  
Tropospheric Chemistry ◽  
Ozone Production ◽  
Industrial Complex ◽  
Peroxy Radicals ◽  
Air Mass ◽  
Field Campaign ◽  
Air Masses ◽  
Photostationary State ◽  
Mass Dependent

Abstract. The NO-NO2 system was analyzed in different chemical regimes/air masses based on observations of reactive nitrogen species and peroxy radicals made during the intensive field campaign MIRAGE-Mex (4 to 29 March 2006). In general, NO2/NO ratios, which can be used as an indicator to test current understanding of tropospheric chemistry mechanism, are near photostationary state. The air masses were categorized into 5 groups: boundary layer (labeled as "BL"), free troposphere (continental, "FTCO" and marine, "FTMA"), biomass burning ("BB"), and Tula industrial complex ("TIC"). The time- and air mass-dependent NO2/NO ratios ranged from 2.35 (TIC) to 5.18 (BB), while the NOx/NOy ratios varied from 0.17 (FTCO) to 0.54 (BL). The ozone production efficiency for the 5 air mass categories ranged from 5.0 (TIC) to 10.2 (BL), indicating photochemically young and reactive air masses.

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