Natural and anthropogenic sources of bromoform and dibromomethane in the oceanographic and biogeochemical regime of the subtropical North East Atlantic

Abstract. The Global Atmospheric Watch research station at Mace Head (Ireland) offers the possibility to sample some of the cleanest air masses being imported into Europe as well as some of the most polluted being exported out of Europe. We present a statistical Cluster~analysis of the physical characteristics of aerosol size distributions in air ranging from the cleanest to the most polluted for the year 2008. Data coverage achieved was 75 % throughout the year. By applying the Hartigan-Wong k-Means method, 12 Clusters were identified as systematically occurring and these 12 Clusters could be further combined into 4 categories with similar characteristics, namely: coastal nucleation category (occurring 21.3 % of the time), open ocean nucleation category (occurring 32.6 % of the time), background clean marine category (occurring 26.1 % of the time) and anthropogenic category (occurring 20 % of the time) aerosol size distributions. The coastal nucleation category is characterised by a clear and dominant nucleation mode at sizes less that 10 nm while the open ocean nucleation category is characterised by a dominant Aitken mode between 15 nm and 50 nm. The background clean marine characteristic is a clear bimodality in the size distribution, although it should be noted that either the Aitken mode or the Accumulation mode may dominate the number concentration. By contrast, the continentally-influenced size distributions are generally more mono-modal, albeit with traces of bi-modality. The open ocean category occurs more often during May, June and July, corresponding with the N. E. Atlantic high biological period. Combined with the relatively high percentage frequency of occurrence (32.6 %), this suggests that the marine biota is an important source of new aerosol particles in N. E. Atlantic Air.

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Vertical distribution of sub-micron aerosol chemical composition from North-Western Europe and the North-East Atlantic

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-9117-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 9117-9150

Author(s):

W. T. Morgan ◽

J. D. Allan ◽

K. N. Bower ◽

G. Capes ◽

J. Crosier ◽

...

Keyword(s):

Organic Matter ◽

Chemical Composition ◽

Vertical Distribution ◽

Western Europe ◽

Vertical Profiles ◽

East Atlantic ◽

Air Masses ◽

North East ◽

The North ◽

The Vertical Distribution

Abstract. A synthesis of UK based airborne in-situ measurements of aerosol properties representing air masses from North-West Europe and the North-East Atlantic is presented. The major focus of the study is the vertical distribution of sub-micron aerosol chemical composition. Vertical profiles are derived from a Quadrupole Aerosol Mass Spectrometer (Q-AMS). Background sub-micron aerosol vertical profiles are identified and are primarily composed of organic matter and sulphate aerosol. Such background conditions occurred predominantly during periods associated with long-range air mass transport across the Atlantic. These instances may serve as useful model input of aerosol to Western Europe. Increased mass concentration episodes are coincident with European outflow and periods of stagnant/recirculating air masses. Such periods are characterised by significantly enhanced concentrations of nitrate aerosol relative to those of organic matter and sulphate. Periods of enhanced ground level PM2.5 loadings are coincident with instances of high nitrate mass fractions measured on-board the aircraft, indicating that nitrate is a significant contributor to regional pollution episodes. The vertical structure of the sulphate and organic aerosol profiles were shown to be primarily driven by large-scale dynamical processes. The vertical distribution of nitrate is likely determined by both dynamic and thermodynamic processes, with chemical partitioning of gas phase precursors to the particle phase occurring at lower temperatures at the top of the boundary layer. Such effects have profound implications for the aerosol's lifetime and subsequent impacts, highlighting the requirement for accurate representation of the aerosol vertical distribution.

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Corrigendum to "Aerosol properties associated with air masses arriving into the North East Atlantic during the 2008 Mace Head EUCAARI intensive observing period: an overview" published in Atmos. Chem. Phys., 10, 8413-8435, 2010

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-8549-2010 ◽

2010 ◽

Vol 10 (17) ◽

pp. 8549-8549 ◽

Cited By ~ 2

Author(s):

M. Dall'Osto ◽

D. Ceburnis ◽

G. Martucci ◽

J. Bialek ◽

R. Dupuy ◽

...

Keyword(s):

Chem Phys ◽

East Atlantic ◽

Air Masses ◽

North East ◽

The North ◽

Aerosol Properties

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Vertical distribution of sub-micron aerosol chemical composition from North-Western Europe and the North-East Atlantic

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-5389-2009 ◽

2009 ◽

Vol 9 (15) ◽

pp. 5389-5401 ◽

Cited By ~ 76

Author(s):

W. T. Morgan ◽

J. D. Allan ◽

K. N. Bower ◽

G. Capes ◽

J. Crosier ◽

...

Keyword(s):

Organic Matter ◽

Chemical Composition ◽

Vertical Distribution ◽

Western Europe ◽

Vertical Profiles ◽

East Atlantic ◽

Air Masses ◽

North East ◽

The North ◽

The Vertical Distribution

Abstract. A synthesis of UK based airborne in-situ measurements of aerosol properties representing air masses from North-West Europe and the North-East Atlantic is presented. The major focus of the study is the vertical distribution of sub-micron aerosol chemical composition. Vertical profiles are derived from a Quadrupole Aerosol Mass Spectrometer (Q-AMS). Background sub-micron aerosol vertical profiles are identified and are primarily composed of organic matter and sulphate aerosol. Such background conditions occurred predominantly during periods associated with long-range air mass transport across the Atlantic. These instances may serve as useful model input of aerosol to Western Europe. Increased mass concentration episodes are coincident with European outflow and periods of stagnant/recirculating air masses. Such periods are characterised by significantly enhanced concentrations of nitrate aerosol relative to those of organic matter and sulphate. Periods of enhanced ground level PM2.5 loadings are coincident with instances of high nitrate mass fractions measured on-board the aircraft, indicating that nitrate is a significant contributor to regional pollution episodes. The vertical structure of the sulphate and organic aerosol profiles were shown to be primarily driven by large-scale dynamical processes. The vertical distribution of nitrate is likely determined by both dynamic and thermodynamic processes, with chemical partitioning of gas phase precursors to the particle phase occurring at lower temperatures at the top of the boundary layer. Such effects have profound implications for the aerosol's lifetime and subsequent impacts, highlighting the requirement for accurate representation of the aerosol vertical distribution.

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Deep convective influence on the UTLS composition in the Asian Monsoon Anticyclone region: 2017 StratoClim campaign results

10.5194/egusphere-egu2020-10709 ◽

2020 ◽

Author(s):

Silvia Bucci ◽

Bernard Legras ◽

Pasquale Sellitto ◽

Francesco D'Amato ◽

Silvia Viciani ◽

...

Keyword(s):

Asian Monsoon ◽

Deep Convection ◽

Direct Injection ◽

Trace Gases ◽

Convective Cloud ◽

Air Masses ◽

The North ◽

Transport Condition ◽

Trajectory System

The StratoClim stratospheric aircraft campaign, taking place in summer over the Nepalese region, provided a wide dataset of observations of air composition inside the Asian Monsoon Anticyclone (AMA). To improve the understanding of the role of penetrating overshoot in the AMA region, we exploit the TRACZILLA Lagrangian simulations, computed on meteorological fields from ECMWF (ERA-Interim and ERA5) at 3h and 1h resolution and using both kinematic and diabatic vertical velocity approaches. The synergy with high-resolution observations of convective cloud top from the MSG1 and Himawari geostationary satellites is used to individuate the convective sources.To evaluate the capability of the trajectory system to reproduce the transport in the UTLS we compare the simulations with the observed trace gases concentration. The ERA5 simulations appear to provide a higher consistency with observed data than ERA-Interim and show a better agreement between the diabatic and kinematic results. The best performance is given by the ERA5 with diabatic transport and, adopting this setting, we analyze the transport condition during the 8 flights of the campaign.The aircraft sampled different convective plumes, often carrying pollutant compounds up to the UTLS level. The highest observed concentration of trace gases had been linked to fresh convective air (younger than a few days) coming from China, Pakistan and the North Indian region.A vertical stratification is observed in the age of air: up to 15 km, the age of air is less than 3 days and these fresh air masses make up nearly the entire totality of the air composition. Above, a transition layer is identified between 15 km and 17 km (close to the tropopause), where the convective influence is still dominant and the ages range from one week to two. Finally, above this layer, the convective influence rapidly decreases toward zero and the mean air age increase to 20 days and more.This study quantifies the contribution of direct injection of deep convection on the UTLS composition based on the aircraft measurements. Preliminary results of the upscale analysis based on the trajectories-satellites system will also be presented.

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