scholarly journals Chemical and meteorological influences on the lifetime of NO<sub>3</sub> at a semi-rural mountain site during PARADE

2016 ◽  
Vol 16 (8) ◽  
pp. 4867-4883 ◽  
Author(s):  
N. Sobanski ◽  
M. J. Tang ◽  
J. Thieser ◽  
G. Schuster ◽  
D. Pöhler ◽  
...  
Keyword(s):  
Loss Rate ◽  
Trace Gases ◽  
Meteorological Conditions ◽  
Biogenic Emissions ◽  
Anthropogenic Emissions ◽  
Air Masses ◽  
Mixing Ratios ◽  
Criegee Intermediates ◽  
Mountain Site ◽  
Meteorological Influences

Abstract. Through measurements of NO2, O3 and NO3 during the PARADE campaign (PArticles and RAdicals, Diel observations of mEchanisms of oxidation) in the German Taunus mountains we derive nighttime steady-state lifetimes (τss) of NO3 and N2O5. During some nights, high NO3 (∼ 200 pptv) and N2O5 (∼ 1 ppbv) mixing ratios were associated with values of τss that exceeded 1 h for NO3 and 3 h for N2O5 near the ground. Such long boundary-layer lifetimes for NO3 and N2O5 are usually only encountered in very clean/unreactive air masses, whereas the PARADE measurement site is impacted by both biogenic emissions from the surrounding forest and anthropogenic emissions from the nearby urbanised/industrialised centres. Measurement of several trace gases which are reactive towards NO3 indicates that the inferred lifetimes are significantly longer than those calculated from the summed loss rate. Several potential causes for the apparently extended NO3 and N2O5 lifetimes are examined, including additional routes to formation of NO3 and the presence of a low-lying residual layer. Overall, the most likely cause of the anomalous lifetimes are related to the meteorological conditions, though additional NO3 formation due to reactions of Criegee intermediates may contribute.

scholarly journals Chemical and meteorological influences on the lifetime of NO<sub>3</sub> at a semirural mountain site during "PARADE"

2016 ◽  
Author(s):  
N. Sobanski ◽  
M. J. Tang ◽  
J. Thieser ◽  
G. Schuster ◽  
D. Pöhler ◽  
...  
Keyword(s):  
Loss Rate ◽  
Trace Gases ◽  
Meteorological Conditions ◽  
Biogenic Emissions ◽  
Anthropogenic Emissions ◽  
Air Masses ◽  
Mixing Ratios ◽  
Criegee Intermediates ◽  
Mountain Site ◽  
Meteorological Influences

Abstract. Through measurements of NO2, O3, and NO3 during the PARADE campaign (PArticles and RAdicals, Diel observations of mEchanisms of oxidation) in the German Taunus mountains we derive nighttime, steady state lifetimes (τss) of NO3 and N2O5. During some nights, high NO3 (~ 200 pptv) and N2O5 (~ 1 ppbv) mixing ratios are associated with values of τss that exceeded one hour for NO3 and three hours for N2O5 near the ground. Such long boundary layer lifetimes for NO3 and N2O5 are usually only encountered in very clean/unreactive air masses whereas the PARADE measurement site is impacted by both biogenic emissions from the surrounding forest and anthropogenic emissions from the nearby urbanized/industrialised centres. Measurement of several trace gases which are reactive towards NO3 indicate that the inferred lifetimes are significantly longer than those calculated from the summed loss rate. Several potential causes for the apparently extended NO3 and N2O5 lifetimes are examined, including additional routes to formation of NO3 and the presence of a low-lying residual layer. Overall, the most likely cause of the anomalous lifetimes are related to the meteorological conditions, though additional NO3 formation due to reactions of Criegee intermediates may contribute.

Trace gases and organic aerosol at a rural site in Vietnam during large scale biomass burning

2021 ◽  
Author(s):  
Simone M. Pieber ◽  
Dac-Loc Nguyen ◽  
Hendryk Czech ◽  
Stephan Henne ◽  
Nicolas Bukowiecki ◽  
...  
Keyword(s):  
Air Quality ◽  
Chemical Composition ◽  
Biomass Burning ◽  
Large Scale ◽  
Trace Gases ◽  
Organic Aerosol ◽  
Trace Gas ◽  
Rural Site ◽  
Air Masses ◽  
Mixing Ratios

&lt;p&gt;Open biomass burning (BB) is a globally widespread phenomenon. The fires release pollutants, which are harmful for human and ecosystem health and alter the Earth's radiative balance. Yet, the impact of various types of BB on the global radiative forcing remains poorly constrained concerning greenhouse gas emissions, BB organic aerosol (OA) chemical composition and related light absorbing properties. Fire emissions composition is influenced by multiple factors (e.g., fuel and thereby vegetation-type, fuel moisture, fire temperature, available oxygen). Due to regional variations in these parameters, studies in different world regions are needed. Here we investigate the influence of seasonally recurring BB on trace gas concentration and air quality at the regional Global Atmosphere Watch (GAW) station Pha Din (PDI) in rural Northwestern Vietnam. PDI is located in a sparsely populated area on the top of a hill (1466 m a.s.l.) and is well suited to study the large-scale fires on the Indochinese Peninsula, whose pollution plumes are frequently transported towards the site [1]. We present continuous trace gas observations of CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt;, CO, and O&lt;sub&gt;3&lt;/sub&gt; conducted at PDI since 2014 and interpret the data with atmospheric transport simulations. Annually recurrent large scale BB leads to hourly time-scale peaks CO mixing ratios at PDI of 1000 to 1500 ppb around every April since the start of data collection in 2014. We complement this analysis with carbonaceous PM&lt;sub&gt;2.5 &lt;/sub&gt;chemical composition analyzed during an intensive campaign in March-April 2015. This includes measurements of elemental and organic carbon (EC/OC) and more than 50 organic markers, such as sugars, PAHs, fatty acids and nitro-aromatics [2]. For the intensive campaign, we linked CO, CO&lt;sub&gt;2&lt;/sub&gt;, CH&lt;sub&gt;4&lt;/sub&gt; and O&lt;sub&gt;3&lt;/sub&gt; mixing ratios to a statistical classification of BB events, which is based on OA composition. We found increased CO and O&lt;sub&gt;3&lt;/sub&gt; levels during medium and high BB influence during the intensive campaign. A backward trajectory analysis confirmed different source regions for the identified periods based on the OA cluster. Typically, cleaner air masses arrived from northeast, i.e., mainland China and Yellow sea during the intensive campaign. The more polluted periods were characterized by trajectories from southwest, with more continental recirculation of the medium cluster, and more westerly advection for the high cluster. These findings highlight that BB activities in Northern Southeast Asia significantly enhances the regional OA loading, chemical PM&lt;sub&gt;2.5 &lt;/sub&gt;composition and the trace gases in northwestern Vietnam. The presented analysis adds valuable data on air quality in a region of scarce data availability.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;REFERENCES&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;[1] Bukowiecki, N. et al. Effect of Large-scale Biomass Burning on Aerosol Optical Properties at the GAW Regional Station Pha Din, Vietnam. AAQR. 19, 1172&amp;#8211;1187 (2019).&lt;/p&gt;&lt;p&gt;[2] Nguyen, D. L, et al. Carbonaceous aerosol composition in air masses influenced by large-scale biomass burning: a case-study in Northwestern Vietnam. ACPD., https://doi.org/10.5194/acp-2020-1027, in review, 2020.&lt;/p&gt;

scholarly journals Total OH reactivity measurements in Paris during the 2010 MEGAPOLI winter campaign

2012 ◽  
Vol 12 (4) ◽  
pp. 10937-10994 ◽  
Author(s):  
C. Dolgorouky ◽  
V. Gros ◽  
R. Sarda-Esteve ◽  
V. Sinha ◽  
J. Williams ◽  
...  
Keyword(s):  
Hydroxyl Radicals ◽  
Loss Rate ◽  
Trace Gases ◽  
Air Masses ◽  
Anthropogenic Origin ◽  
Inorganic Species ◽  
Surrounding Areas ◽  
Marine Air ◽  
First Time ◽  
Comparative Reactivity

Abstract. Hydroxyl radicals play a central role in the troposphere as they control the lifetime of many trace gases. Measurement of OH reactivity (OH loss rate) is important to better constrain the OH budget and also to evaluate the completeness of measured VOC budget. Total atmospheric OH reactivity was measured for the first time in an European Megacity: Paris and its surrounding areas with 12 million inhabitants, during the MEGAPOLI winter campaign 2010. The method deployed was the Comparative Reactivity Method (CRM). The measured dataset contains both measured and calculated OH reactivity from CO, NOx and VOCs measured via PTR-MS, GC-FID and GC-MS instruments. The reactivities observed in Paris covered a range from 10 s−1 to 130 s−1, indicating a large loading of chemical reactants. The present study showed that, when clean marine air masses influenced Paris, the purely local OH reactivity (20 s−1) is well explained by the measured species. Nevertheless, when there is a continental import of air masses, high levels of OH reactivity were obtained (120–130 s−1) and the missing OH reactivity measured in this case jumped to 75%. Using covariations of the missing OH reactivity to secondary inorganic species in fine aerosols, we suggest that the missing OH reactants were most likely highly oxidized compounds issued from photochemically processed air masses of anthropogenic origin.

scholarly journals Physical and chemical properties of the regional mixed layer of Mexico's Megapolis Part II: evaluation of measured and modeled trace gases and particle size distributions

2012 ◽  
Vol 12 (21) ◽  
pp. 10161-10179 ◽  
Author(s):  
C. Ochoa ◽  
D. Baumgardner ◽  
M. Grutter ◽  
J. Allan ◽  
J. Fast ◽  
...  
Keyword(s):  
Particle Size ◽  
Standard Deviation ◽  
Transport Model ◽  
Trace Gases ◽  
Research Station ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Air Masses ◽  
Accumulation Mode ◽  
Mountain Site

Abstract. This study extends the work of Baumgardner et al. (2009) in which measurements of trace gases and particles, at a remote, high altitude mountain site, 60 km from Mexico City were analyzed with respect to the origin of the air masses. In the current evaluation, the temperature, water vapor mixing ratio (WMR), ozone (O3), carbon monoxide (CO), sulfur dioxide (SO2) and acyl peroxy nitrate (APN) are simulated with the WRF-Chem chemical transport model and compared with the measurements at the mountain site. Comparisons between the model and measurements are also evaluated for particle size distributions (PSDs) of the mass concentrations of sulfate, nitrate, ammonium and organic mass (OM). The model predictions of the diurnal trends in temperature, WMR and trace gases were generally well correlated; 13 of the 18 correlations were significant at a confidence level of <0.01. Less satisfactory were the average hourly differences between model and measurements that showed predicted values within expected, natural variation for only 10 of the 18 comparisons. The model performed best when comparing with the measurements during periods when the air originated from the east. In that case all six of the parameters being compared had average differences between the model and measurements less than the expected standard deviation. For the cases when the air masses are from the southwest or west northwest, only two of the comparisons from each case showed differences less than the expected standard deviation. The differences appear to be a result of an overly rapid growth of the boundary layer predicted by the model and too much dilution. There also is more O3 being produced, most likely by photochemical production, downwind of the emission sources than is predicted by the model. The measured and modeled PSD compare very well with respect to their general shape and the diameter of the peak concentrations. The spectra are log normally distributed with most of the mass in the accumulation mode centered at 200 ± 20 nm and little observed or predicted changes with respect to the time when the RML is above the Altzomoni research station. Only the total mass changes with time and air mass origin. The invariability of average diameter of the accumulation mode suggests that there is very little growth of the particles by condensation or coagulation after six hours of aging downwind of the major sources of anthropogenic emissions in Mexico's Megapolis. This could greatly simplify parameterization in climate models although it is not known at this time if this invariance can be extended to other megacity regions.

scholarly journals Worsening urban ozone pollution in China from 2013 to 2017 – Part 1: The complex and varying roles of meteorology

2020 ◽  
Author(s):  
Yiming Liu ◽  
Tao Wang
Keyword(s):  
Wind Field ◽  
Urban Areas ◽  
Emission Control ◽  
Meteorological Conditions ◽  
Specific Humidity ◽  
Biogenic Emissions ◽  
Anthropogenic Emissions ◽  
Ozone Pollution ◽  
The Impact ◽  
Ozone Levels

Abstract. China has suffered from increasing levels of ozone pollution in urban areas despite the implementation of various stringent emission reduction measures since 2013. In this study, we conducted numerical experiments with an up-to-date regional chemical transport model to assess the contribution of the changes in meteorological conditions and anthropogenic emissions to the summer ozone level from 2013 to 2017 in various regions of China. The model can faithfully reproduce the observed meteorological parameters and air pollutant concentrations and capture the increasing trend in the surface maximum daily 8-hour average (MDA8) ozone (O3) from 2013 to 2017. The emission control measures implemented by the government induced a decrease in MDA8 O3 levels in rural areas but an increase in urban areas. The meteorological influence on the ozone trend varied by region and by year and could be comparable to or even more significant than the impact of changes in anthropogenic emissions. Meteorological conditions can modulate the ozone concentration via direct (e.g., increasing reaction rates at higher temperatures) and indirect (e.g., increasing biogenic emissions at higher temperatures) effects. As an essential source of volatile organic compounds that contributes to ozone formation, the variation in biogenic emissions during summer varied across regions and was mainly affected by temperature. China’s midlatitude areas (25° N to 40° N) experienced a significant decrease in MDA8 O3 due to a decline in biogenic emissions, especially for the Yangtze River Delta and Sichuan Basin regions in 2014 and 2015. In contrast, in northern (north of 40° N) and southern (south of 25° N) China, higher temperatures after 2013 led to an increase in MDA8 O3 concentrations via an increase in biogenic emissions. We also assessed the individual effects of changes in temperature, specific humidity, wind field, planetary boundary layer height, clouds, and precipitation on ozone levels from 2013 to 2017. The results show that the wind field change made a significant contribution to the increase in surface ozone over China by transporting the ozone downward from the upper troposphere and the lower stratosphere. The long-range transport of ozone and its precursors outside the modeling domain also contributed to the increase in MDA8 O3 in China, especially on the Tibetan Plateau (an increase of 1 to 4 ppbv). Our study represents the most comprehensive and up-to-date analysis of the impact of changes in meteorology on ozone across China and highlights the importance of considering meteorological variations when assessing the effectiveness of emission control on changes in the ozone levels in recent years.

scholarly journals Total OH reactivity measurements in Paris during the 2010 MEGAPOLI winter campaign

2012 ◽  
Vol 12 (20) ◽  
pp. 9593-9612 ◽  
Author(s):  
C. Dolgorouky ◽  
V. Gros ◽  
R. Sarda-Esteve ◽  
V. Sinha ◽  
J. Williams ◽  
...  
Keyword(s):  
Hydroxyl Radicals ◽  
Loss Rate ◽  
Trace Gases ◽  
Air Masses ◽  
Anthropogenic Origin ◽  
Inorganic Species ◽  
Surrounding Areas ◽  
Marine Air ◽  
First Time ◽  
Comparative Reactivity

Abstract. Hydroxyl radicals play a central role in the troposphere as they control the lifetime of many trace gases. Measurement of OH reactivity (OH loss rate) is important to better constrain the OH budget and also to evaluate the completeness of measured VOC budget. Total atmospheric OH reactivity was measured for the first time in an European Megacity: Paris and its surrounding areas with 12 million inhabitants, during the MEGAPOLI winter campaign 2010. The method deployed was the Comparative Reactivity Method (CRM). The measured dataset contains both measured and calculated OH reactivity from CO, NOx and VOCs measured via PTR-MS, GC-FID and GC-MS instruments. The reactivities observed in Paris covered a range from 10 s−1 to 130 s−1, indicating a large loading of chemical reactants. The present study showed that, when clean marine air masses influenced Paris, the purely local OH reactivity (20 s−1) is well explained by the measured species. Nevertheless, when there is a continental import of air masses, high levels of OH reactivity were obtained (120–130 s−1) and the missing OH reactivity measured in this case jumped to 75%. Using covariations of the missing OH reactivity to secondary inorganic species in fine aerosols, we suggest that the missing OH reactants were most likely highly oxidized compounds issued from photochemically processed air masses of anthropogenic origin.

scholarly journals Characterization of submicron particles influenced by mixed biogenic and anthropogenic emissions using high-resolution aerosol mass spectrometry: results from CARES

2012 ◽  
Vol 12 (17) ◽  
pp. 8131-8156 ◽  
Author(s):  
A. Setyan ◽  
Q. Zhang ◽  
M. Merkel ◽  
W. B. Knighton ◽  
Y. Sun ◽  
...  
Keyword(s):  
High Resolution ◽  
Sierra Nevada ◽  
Oxidation Products ◽  
Biogenic Emissions ◽  
Anthropogenic Emissions ◽  
Mass Loading ◽  
Large Variability ◽  
Air Masses ◽  
Aerosol Mass ◽  
Urban Plumes

Abstract. An Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed during the Carbonaceous Aerosols and Radiative Effects Study (CARES) that took place in northern California in June 2010. We present results obtained at Cool (denoted as the T1 site of the project) in the foothills of the Sierra Nevada Mountains, where intense biogenic emissions are periodically mixed with urban outflow transported by daytime southwesterly winds from the Sacramento metropolitan area. During this study, the average mass loading of submicrometer particles (PM1) was 3.0 μg m−3, dominated by organics (80%) and sulfate (9.9%). The organic aerosol (OA) had a nominal formula of C1H1.38N0.004OM0.44, thus an average organic mass-to-carbon (OM/OC) ratio of 1.70. Two distinct oxygenated OA factors were identified via Positive matrix factorization (PMF) of the high-resolution mass spectra of organics. The more oxidized MO-OOA (O/C = 0.54) was interpreted as a surrogate for secondary OA (SOA) influenced by biogenic emissions whereas the less oxidized LO-OOA (O/C = 0.42) was found to represent SOA formed in photochemically processed urban emissions. LO-OOA correlated strongly with ozone and MO-OOA correlated well with two 1st generation isoprene oxidation products (methacrolein and methyl vinyl ketone), indicating that both SOAs were relatively fresh. A hydrocarbon like OA (HOA) factor was also identified, representing primary emissions mainly due to local traffic. On average, SOA (= MO-OOA + LO-OOA) accounted for 91% of the total OA mass and 72% of the PM1 mass observed at Cool. Twenty three periods of urban plumes from T0 (Sacramento) to T1 (Cool) were identified using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). The average PM1 mass loading was considerably higher in urban plumes than in air masses dominated by biogenic SOA. The change in OA mass relative to CO (ΔOA/ΔCO) varied in the range of 5-196 μg m−3 ppm−1, reflecting large variability in SOA production. The highest ΔOA/ΔCO was reached when air masses were dominated by anthropogenic emissions in the presence of a high concentration of biogenic volatile organic compounds (BVOCs). This ratio, which was 97 μg m−3 ppm−1 on average, was much higher than when urban plumes arrived in a low BVOC environment (~36 μg m−3 ppm−1) or during other periods dominated by biogenic SOA (35 μg m−3 ppm−1). These results demonstrate that SOA formation is enhanced when anthropogenic emissions interact with biogenic precursors.

scholarly journals Worsening urban ozone pollution in China from 2013 to 2017 – Part 1: The complex and varying roles of meteorology

2020 ◽  
Vol 20 (11) ◽  
pp. 6305-6321 ◽  
Author(s):  
Yiming Liu ◽  
Tao Wang
Keyword(s):  
Wind Field ◽  
Urban Areas ◽  
Emission Control ◽  
Meteorological Conditions ◽  
Specific Humidity ◽  
Biogenic Emissions ◽  
Anthropogenic Emissions ◽  
Ozone Pollution ◽  
The Impact ◽  
Ozone Levels

Abstract. China has suffered from increasing levels of ozone pollution in urban areas despite the implementation of various stringent emission reduction measures since 2013. In this study, we conducted numerical experiments with an up-to-date regional chemical transport model to assess the contribution of the changes in meteorological conditions and anthropogenic emissions to the summer ozone level from 2013 to 2017 in various regions of China. The model can faithfully reproduce the observed meteorological parameters and air pollutant concentrations and capture the increasing trend in the surface maximum daily 8 h average (MDA8) ozone (O3) from 2013 to 2017. The emission-control measures implemented by the government induced a decrease in MDA8 O3 levels in rural areas but an increase in urban areas. The meteorological influence on the ozone trend varied by region and by year and could be comparable to or even more significant than the impact of changes in anthropogenic emissions. Meteorological conditions can modulate the ozone concentration via direct (e.g., increasing reaction rates at higher temperatures) and indirect (e.g., increasing biogenic emissions at higher temperatures) effects. As an essential source of volatile organic compounds that contributes to ozone formation, the variation in biogenic emissions during summer varied across regions and was mainly affected by temperature. China's midlatitude areas (25 to 40∘ N) experienced a significant decrease in MDA8 O3 due to a decline in biogenic emissions, especially for the Yangtze River Delta and Sichuan Basin regions in 2014 and 2015. In contrast, in northern (north of 40∘ N) and southern (south of 25∘ N) China, higher temperatures after 2013 led to an increase in MDA8 O3 via an increase in biogenic emissions. We also assessed the individual effects of changes in temperature, specific humidity, wind field, planetary boundary layer height, clouds, and precipitation on ozone levels from 2013 to 2017. The results show that the wind field change made a significant contribution to the increase in surface ozone over many parts of China. The long-range transport of ozone and its precursors from outside the modeling domain also contributed to the increase in MDA8 O3 in China, especially on the Qinghai–Tibetan Plateau (an increase of 1 to 4 ppbv). Our study represents the most comprehensive and up-to-date analysis of the impact of changes in meteorology on ozone across China and highlights the importance of considering meteorological variations when assessing the effectiveness of emission control on changes in the ozone levels in recent years.

scholarly journals Measurements of reactive chlorocarbons over the Surinam tropical rain forest: indications for strong biogenic emissions

2003 ◽  
Vol 3 (5) ◽  
pp. 5469-5512 ◽  
Author(s):  
H. A. Scheeren ◽  
J. Lelieveld ◽  
J. Williams ◽  
H. Fischer ◽  
C. Warneke
Keyword(s):  
Biomass Burning ◽  
Methyl Chloride ◽  
Global Scale ◽  
Anthropogenic Sources ◽  
Biogenic Emissions ◽  
Gas Chromatograph ◽  
Air Masses ◽  
Mixing Ratios ◽  
Potential Source ◽  
The Tropics

Abstract. Contrary to the understanding of the emissions and chemical behavior of halocarbons from anthropogenic sources (e.g. CFCs and HCFCs), the biogeochemistry of naturally emitted halocarbons is still poorly understood. We present measurements of chloromethane (methyl chloride, CH3Cl), trichloromethane (chloroform, CHCl3), dichloromethane (CH2Cl2), and tetrachloroethylene (C2Cl4) from air samples taken over the Surinam rainforest during the 1998 LBA/CLAIRE campaign. The samples were collected in stainless steel canisters on-board a Cessna Citation jet aircraft and analyzed in the laboratory using a gas chromatograph equipped with FID and ECD. The chlorocarbons we studied have atmospheric lifetimes of ~1 year or less, and appear to have significant emissions from natural sources including oceans, soils and vegetations, as well as biomass burning. These sources are primarily concentrated in the tropics (30º N-30º S). We detected an increase as a function of latitude of methyl chloride, chloroform, and tetrachloroethylene mixing ratios, in pristine air masses advected from the Atlantic Ocean toward the central Amazon. In the absence of significant biomass burning sources, we attribute this increase to biogenic emissions from the Surinam rainforest. From our measurements, we deduce fluxes from the Surinam rainforest of 7.6±1.8 μg CH3Cl m−2 h−1, 1.11±0.08g CHCl3 μm−2 h−1, and 0.36±0.07 μg C2Cl4 m−2 h−1. Extrapolated to a global scale, our emission estimates suggest a large potential source of 2 Tg CH3Cl yr−1 from tropical forests, which could account for the net budget discrepancy (underestimation of sources), as indicated previously. In addition, our estimates suggest a potential emission of 57±17 Gg C2C4 yr−1 from tropical forest soils, equal to half of the currently missing C2Cl4 sources. We hypothesize that the extensive deforestation over the last two decades relates to the observed global downward trend of atmospheric methyl chloride.

scholarly journals A stratospheric intrusion at the subtropical jet over the Mediterranean Sea: air-borne remote sensing observations and model results

2012 ◽  
Vol 12 (18) ◽  
pp. 8423-8438 ◽  
Author(s):  
K. Weigel ◽  
L. Hoffmann ◽  
G. Günther ◽  
F. Khosrawi ◽  
F. Olschewski ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Mediterranean Sea ◽  
Trace Gases ◽  
Analysis Data ◽  
Lagrangian Model ◽  
Air Masses ◽  
Mixing Ratios ◽  
Stratospheric Intrusion ◽  
Subtropical Jet ◽  
The Mediterranean

Abstract. Remote sensing measurements from the Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers (CRISTA-NF) during a flight on 29 July 2006 are presented. This flight is part of the AMMA-SCOUT-O3 measurement campaign, where CRISTA-NF was deployed on the high-flying research aircraft M55-Geophysica. The flight path was located over Italy and the Mediterranean Sea and crossed over the subtropical jet twice. Measurements of temperature, and the volume mixing ratios of water vapor (H2O), ozone (O3), nitric acid (HNO3) and peroxyacetyl nitrate (PAN) are available with a vertical resolution of up to 500 m between about 6 to 21 km altitude. CRISTA-NF observes these trace gases simultaneously and provides a quasi-2-D view of the transition region between the troposphere and the stratosphere. The observation of these different trace gases allows to determine tropospheric and stratospheric air masses. As expected, higher abundances are found where the main source of the trace gases is located: in the stratosphere for O3 and in the troposphere for H2O and PAN. Tracer-tracer correlations between O3 and PAN are used to identify the mixed tropospheric and lowermost stratospheric air at the subtropical jet and around the thermal tropopause north of the jet. An intrusion of stratospheric air into the troposphere associated with the subtropical jet is found in the CRISTA-NF observations. The observations indicate that the intrusion is connected to a tropopause fold which is not resolved in the ECMWF analysis data. The intrusion was reproduced in a simulation with the Chemical Lagrangian Model of the Stratosphere (CLaMS). The CLaMS simulation shows, that the lowermost stratospheric air masses in the intrusion where transported along the the subtropical jet. The tropospheric air masses around the intrusion originate from the vicinity of the Asian monsoon anticyclone. This work discusses the nature of the observed processes at the subtropical jet based on the CRISTA-NF observations and the CLaMS simulation.

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