Dynamical and thermodynamical coupling between the North Atlantic subtropical high and the marine boundary layer clouds in boreal summer

Abstract. The North Atlantic Marine Boundary Layer Experiment (NAMBLEX), involving over 50 scientists from 12 institutions, took place at Mace Head, Ireland (53.32° N, 9.90° W), between 23 July and 4 September 2002. A wide range of state-of-the-art instrumentation enabled detailed measurements of the boundary layer structure and atmospheric composition in the gas and aerosol phase to be made, providing one of the most comprehensive in situ studies of the marine boundary layer to date. This overview paper describes the aims of the NAMBLEX project in the context of previous field campaigns in the Marine Boundary Layer (MBL), the overall layout of the site, a summary of the instrumentation deployed, the temporal coverage of the measurement data, and the numerical models used to interpret the field data. Measurements of some trace species were made for the first time during the campaign, which was characterised by predominantly clean air of marine origin, but more polluted air with higher levels of NOx originating from continental regions was also experienced. This paper provides a summary of the meteorological measurements and Planetary Boundary Layer (PBL) structure measurements, presents time series of some of the longer-lived trace species (O3, CO, H2, DMS, CH4, NMHC, NOx, NOy, PAN) and summarises measurements of other species that are described in more detail in other papers within this special issue, namely oxygenated VOCs, HCHO, peroxides, organo-halogenated species, a range of shorter lived halogen species (I2, OIO, IO, BrO), NO3 radicals, photolysis frequencies, the free radicals OH, HO2 and (HO2+Σ RO2), as well as a summary of the aerosol measurements. NAMBLEX was supported by measurements made in the vicinity of Mace Head using the NERC Dornier-228 aircraft. Using ECMWF wind-fields, calculations were made of the air-mass trajectories arriving at Mace Head during NAMBLEX, and were analysed together with both meteorological and trace-gas measurements. In this paper a chemical climatology for the duration of the campaign is presented to interpret the distribution of air-mass origins and emission sources, and to provide a convenient framework of air-mass classification that is used by other papers in this issue for the interpretation of observed variability in levels of trace gases and aerosols.

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Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-10223-2010 ◽

2010 ◽

Vol 10 (21) ◽

pp. 10223-10236 ◽

Cited By ~ 92

Author(s):

J. B. Gilman ◽

J. F. Burkhart ◽

B. M. Lerner ◽

E. J. Williams ◽

W. C. Kuster ◽

...

Keyword(s):

Boundary Layer ◽

North Atlantic ◽

Marine Boundary Layer ◽

Transport Model ◽

Arctic Basin ◽

The Arctic ◽

Arctic Boundary Layer ◽

Air Masses ◽

The North ◽

The North Atlantic

Abstract. The influence of halogen oxidation on the variabilities of ozone (O3) and volatile organic compounds (VOCs) within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68° N) was observed between the acetylene to benzene ratio, used as a marker for chlorine and bromine oxidation, and O3 signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O3 variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O3-poor air masses from the Arctic Basin to latitudes as far south as 52° N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI), multi-year ice (MYI), and total ICE (FYI+MYI). O3 anti-correlated with the modeled total ICE tracer (r = −0.86) indicating that up to 73% of the O3 variability measured in the Arctic marine boundary layer could be related to sea ice exposure.

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Nitrogen oxides and ozone production in the North Atlantic marine boundary layer

Journal of Geophysical Research Atmospheres ◽

10.1029/96jd03511 ◽

1997 ◽

Vol 102 (D9) ◽

pp. 10653-10665 ◽

Cited By ~ 18

Author(s):

Thomas P. Carsey ◽

Dean D. Churchill ◽

Michael L. Farmer ◽

Charles J. Fischer ◽

Alexander A. Pszenny ◽

...

Keyword(s):

Boundary Layer ◽

Nitrogen Oxides ◽

North Atlantic ◽

Marine Boundary Layer ◽

Ozone Production ◽

The North ◽

The North Atlantic

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Episodic removal of NOyspecies from the marine boundary layer over the North Atlantic

Journal of Geophysical Research Atmospheres ◽

10.1029/96jd02632 ◽

1996 ◽

Vol 101 (D22) ◽

pp. 28947-28960 ◽

Cited By ~ 46

Author(s):

James M. Roberts ◽

David D. Parrish ◽

Richard B. Norton ◽

Steven B. Bertman ◽

John S. Holloway ◽

...

Keyword(s):

Boundary Layer ◽

North Atlantic ◽

Marine Boundary Layer ◽

The North ◽

The North Atlantic

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Influence of the North Atlantic Subtropical High on wet and dry sea-breeze events in North Carolina, United States

Investigaciones Geográficas ◽

10.14198/ingeo2017.68.01 ◽

2017 ◽

pp. 9 ◽

Cited By ~ 3

Author(s):

Nicholas T. Luchetti ◽

Rosana Nieto Ferreira ◽

Thomas M. Rickenbach ◽

Mark R. Nissenbaum ◽

Joel D. McAuliffe

Keyword(s):

United States ◽

North Carolina ◽

North Atlantic ◽

Convective Available Potential Energy ◽

Sea Breeze ◽

The United States ◽

Subtropical High ◽

North Atlantic Subtropical High ◽

The North ◽

The North Atlantic

The sea-breeze (SB) is an important source of summertime precipitation in North Carolina (NC, southeast United States). However, not all SB events produce precipitation. A climatology of wet and dry SB events in NC is used to investigate the conditions that are conducive to precipitation associated with the sea breeze. Radar imagery was used to detect 88 SB events that occurred along the NC coast between May-September of 2009-2012. The majority (85%) of SB events occurred during offshore flow (53%) or during flow that was parallel to the coast (22%). SB events were separated into dry (53%) and wet (47%) events and differences in the dynamic and thermodynamic parameters of the environment in which they formed were analyzed. Significant differences in dynamic and thermodynamic conditions were found. SB dry events occurred under stronger winds (6.00 ± 2.36 ms-1) than SB wet events (4.02 ± 2.16 ms-1). Moreover, during SB wet events larger values of convective available potential energy and lower values of convective inhibition were present, conditions that favor precipitation. Overall, the SB wet events accounted for 20-30% of the May-September precipitation along the NC coastal region. The position of the North Atlantic Subtropical High (NASH) controls both moisture availability and winds along the NC coast, thus providing a synoptic-scale control mechanism for SB precipitation. In particular, it was shown that when the NASH western ridge is located along the southeast coast of the United States, it causes a moist southwesterly flow along the NC coast that may favor the occurrence of SB wet events.

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Reply to “Comments on ‘Changes to the North Atlantic Subtropical High and Its Role in the Intensification of Summer Rainfall Variability in the Southeastern United States’”

Journal of Climate ◽

10.1175/jcli-d-11-00674.1 ◽

2013 ◽

Vol 26 (2) ◽

pp. 683-688 ◽

Cited By ~ 9

Author(s):

Wenhong Li ◽

Laifang Li ◽

Rong Fu ◽

Yi Deng ◽

Hui Wang

Keyword(s):

North Atlantic ◽

Rainfall Variability ◽

Southeastern United States ◽

Summer Rainfall ◽

Subtropical High ◽

North Atlantic Subtropical High ◽

The North ◽

Westward Movement ◽

The North Atlantic ◽

Potential Impact

Abstract Recently Diem questioned the western ridge movement of the North Atlantic subtropical high (NASH) reported in a 2011 paper of Li et al. This reply shows more analysis that further strengthens the conclusions originally put forth by Li et al. Diem’s analysis of the trend in the western ridge of the NASH was based on the data over a 30-yr period (1978–2007), whereas the main conclusions in Li et al. were drawn according to the data over a 60-yr period (1948–2007). Over the last 60 years, the NASH has shown a significant trend of westward movement, the meridional movement of the western ridge of the NASH has enhanced in the recent three decades, and the potential impact of global warming cannot be ruled out in an attempt to explain these changes of the NASH.

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Peroxyacetyl nitrate in the North Atlantic marine boundary layer

Global Biogeochemical Cycles ◽

10.1029/gb004i003p00297 ◽

1990 ◽

Vol 4 (3) ◽

pp. 297-308 ◽

Cited By ~ 15

Author(s):

Michael S. Gallagher ◽

Thomas P. Carsey ◽

Michael L. Farmer

Keyword(s):

Boundary Layer ◽

North Atlantic ◽

Marine Boundary Layer ◽

Peroxyacetyl Nitrate ◽

The North ◽

The North Atlantic

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Black carbon in the marine boundary layer over the North Atlantic and seas of the Russian arctic in june-september 2017

Океанология ◽

10.31857/s0030-1574595771-776 ◽

2019 ◽

Vol 59 (5) ◽

pp. 771-776

Author(s):

V. P. Shevchenko ◽

V. M. Kopeikin ◽

A. N. Novigatsky ◽

G. V. Malafeev

Keyword(s):

Boundary Layer ◽

Black Carbon ◽

North Atlantic ◽

Marine Boundary Layer ◽

The Arctic ◽

Air Masses ◽

South Eastern ◽

The North ◽

The North Atlantic ◽

Eastern Baltic

The paper presents the results of a study of the concentrations of black carbon in the marine boundary layer over the Baltic and North Seas, the North Atlantic, the Norwegian, the Barents, the Kara and the Laptev seas from June 30 to September 29, 2017 in the 68th and 69th voyages of research vessel "Akademik Mstislav Keldysh". Black carbon has a significant impact on climate change and the degree of pollution of the Arctic. Black carbon is formed as a result of incomplete combustion of fossil fuels (primarily coal, oil) and biomass or biofuel. It consists of submicron particles and their aggregates and can be transported a great distance from the source. Samples were taken by pumping air for 46 hours through quartz filters Hahnemule at an altitude of 10 m above sea level in a headwind to prevent smoke of the vessel from entering the filters. Subsequently, the black carbon content was determined in the laboratory by the aetalometric method. The backward trajectories of the air mass transfer and the black carbon particles transported by them to the sampling points were calculated using the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model at http://www.arl.noaa.gov/ready.html. The conducted studies show low values of black carbon concentrations (50 ng/m3) along the expedition route when air masses came from the background areas of the North Atlantic and the Arctic. High concentrations of black carbon (100200 ng/m3 and higher) are characteristic for areas with active navigation (the South-Eastern Baltic, the North Sea) and near ports (eg Reykjavik), as well as for incoming air masses from the industrialized regions of Europe to South-Eastern Baltic and from areas of oil and gas fields where associated gas is flared (the North, the Norwegian and the Kara seas).

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