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G. Vaughan
,
C. Schiller
,
A. R. MacKenzie
,
K. Bower
,
T. Peter
,
H. Schlager
,
N. R. P. Harris
, and
P. T. May

During November and December 2005, two consortia of mainly European groups conducted an aircraft campaign in Darwin, Australia, to measure the composition of the tropical upper-troposphere and tropopause regions, between 12 and 20 km, in order to investigate the transport and transformation in deep convection of water vapor, aerosols, and trace chemicals. The campaign used two high-altitude aircraft—the Russian M55 Geophysica and the Australian Grob 520 Egrett, which can reach 20 and 15 km, respectively—complemented by upward-pointing lidar measurements from the DLR Falcon and low-level aerosol and chemical measurements from the U.K. Dornier-228. The meteorology during the campaign was characterized mainly by premonsoon conditions—isolated afternoon thunderstorms with more organized convective systems in the evening and overnight. At the beginning of November pronounced pollution resulting from widespread biomass burning was measured by the Dornier, giving way gradually to cleaner conditions by December, thus affording the opportunity to study the influence of aerosols on convection. The Egrett was used mainly to sample in and around the outflow from isolated thunderstorms, with a couple of survey missions near the end. The Geophysica–Falcon pair spent about 40% of their flight hours on survey legs, prioritizing remote sensing of water vapor, cirrus, and trace gases, and the remainder on close encounters with storm systems, prioritizing in situ measurements. Two joint missions with all four aircraft were conducted: on 16 November, during the polluted period, sampling a detached anvil from a single-cell storm, and on 30 November, around a much larger multicellular storm.

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A. Roiger
,
J.-L. Thomas
,
H. Schlager
,
K. S. Law
,
J. Kim
,
A. Schäfler
,
B. Weinzierl
,
F. Dahlkötter
,
I. Krisch
,
L. Marelle
,
A. Minikin
,
J.-C. Raut
,
A. Reiter
,
M. Rose
,
M. Scheibe
,
P. Stock
,
R. Baumann
,
I. Bouarar
,
C. Clerbaux
,
M. George
,
T. Onishi
, and
J. Flemming

Abstract

Arctic sea ice has decreased dramatically in the past few decades and the Arctic is increasingly open to transit shipping and natural resource extraction. However, large knowledge gaps exist regarding composition and impacts of emissions associated with these activities. Arctic hydrocarbon extraction is currently under development owing to the large oil and gas reserves in the region. Transit shipping through the Arctic as an alternative to the traditional shipping routes is currently underway. These activities are expected to increase emissions of air pollutants and climate forcers (e.g., aerosols, ozone) in the Arctic troposphere significantly in the future. The authors present the first measurements of these activities off the coast of Norway taken in summer 2012 as part of the European Arctic Climate Change, Economy, and Society (ACCESS) project. The objectives include quantifying the impact that anthropogenic activities will have on regional air pollution and understanding the connections to Arctic climate. Trace gas and aerosol concentrations in pollution plumes were measured, including emissions from different ship types and several offshore extraction facilities. Emissions originating from industrial activities (smelting) on the Kola Peninsula were also sampled. In addition, pollution plumes originating from Siberian biomass burning were probed in order to put the emerging local pollution within a broader context. In the near future these measurements will be combined with model simulations to quantify the influence of local anthropogenic activities on Arctic composition. Here the authors present the scientific objectives of the ACCESS aircraft experiment and the the meteorological conditions during the campaign, and they highlight first scientific results from the experiment.

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C. Flamant
,
P. Knippertz
,
A. H. Fink
,
A. Akpo
,
B. Brooks
,
C. J. Chiu
,
H. Coe
,
S. Danuor
,
M. Evans
,
O. Jegede
,
N. Kalthoff
,
A. Konaré
,
C. Liousse
,
F. Lohou
,
C. Mari
,
H. Schlager
,
A. Schwarzenboeck
,
B. Adler
,
L. Amekudzi
,
J. Aryee
,
M. Ayoola
,
A. M. Batenburg
,
G. Bessardon
,
S. Borrmann
,
J. Brito
,
K. Bower
,
F. Burnet
,
V. Catoire
,
A. Colomb
,
C. Denjean
,
K. Fosu-Amankwah
,
P. G. Hill
,
J. Lee
,
M. Lothon
,
M. Maranan
,
J. Marsham
,
R. Meynadier
,
J.-B. Ngamini
,
P. Rosenberg
,
D. Sauer
,
V. Smith
,
G. Stratmann
,
J. W. Taylor
,
C. Voigt
, and
V. Yoboué

Abstract

The European Union (EU)-funded project Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa (DACCIWA) investigates the relationship between weather, climate, and air pollution in southern West Africa—an area with rapid population growth, urbanization, and an increase in anthropogenic aerosol emissions. The air over this region contains a unique mixture of natural and anthropogenic gases, liquid droplets, and particles, emitted in an environment in which multilayer clouds frequently form. These exert a large influence on the local weather and climate, mainly owing to their impact on radiation, the surface energy balance, and thus the diurnal cycle of the atmospheric boundary layer.

In June and July 2016, DACCIWA organized a major international field campaign in Ivory Coast, Ghana, Togo, Benin, and Nigeria. Three supersites in Kumasi, Savè, and Ile-Ife conducted permanent measurements and 15 intensive observation periods. Three European aircraft together flew 50 research flights between 27 June and 16 July 2016, for a total of 155 h. DACCIWA scientists launched weather balloons several times a day across the region (772 in total), measured urban emissions, and evaluated health data. The main objective was to build robust statistics of atmospheric composition, dynamics, and low-level cloud properties in various chemical landscapes to investigate their mutual interactions.

This article presents an overview of the DACCIWA field campaign activities as well as some first research highlights. The rich data obtained during the campaign will be made available to the scientific community and help to advance scientific understanding, modeling, and monitoring of the atmosphere over southern West Africa.

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Mary C. Barth
,
Christopher A. Cantrell
,
William H. Brune
,
Steven A. Rutledge
,
James H. Crawford
,
Heidi Huntrieser
,
Lawrence D. Carey
,
Donald MacGorman
,
Morris Weisman
,
Kenneth E. Pickering
,
Eric Bruning
,
Bruce Anderson
,
Eric Apel
,
Michael Biggerstaff
,
Teresa Campos
,
Pedro Campuzano-Jost
,
Ronald Cohen
,
John Crounse
,
Douglas A. Day
,
Glenn Diskin
,
Frank Flocke
,
Alan Fried
,
Charity Garland
,
Brian Heikes
,
Shawn Honomichl
,
Rebecca Hornbrook
,
L. Gregory Huey
,
Jose L. Jimenez
,
Timothy Lang
,
Michael Lichtenstern
,
Tomas Mikoviny
,
Benjamin Nault
,
Daniel O’Sullivan
,
Laura L. Pan
,
Jeff Peischl
,
Ilana Pollack
,
Dirk Richter
,
Daniel Riemer
,
Thomas Ryerson
,
Hans Schlager
,
Jason St. Clair
,
James Walega
,
Petter Weibring
,
Andrew Weinheimer
,
Paul Wennberg
,
Armin Wisthaler
,
Paul J. Wooldridge
, and
Conrad Ziegler

Abstract

The Deep Convective Clouds and Chemistry (DC3) field experiment produced an exceptional dataset on thunderstorms, including their dynamical, physical, and electrical structures and their impact on the chemical composition of the troposphere. The field experiment gathered detailed information on the chemical composition of the inflow and outflow regions of midlatitude thunderstorms in northeast Colorado, west Texas to central Oklahoma, and northern Alabama. A unique aspect of the DC3 strategy was to locate and sample the convective outflow a day after active convection in order to measure the chemical transformations within the upper-tropospheric convective plume. These data are being analyzed to investigate transport and dynamics of the storms, scavenging of soluble trace gases and aerosols, production of nitrogen oxides by lightning, relationships between lightning flash rates and storm parameters, chemistry in the upper troposphere that is affected by the convection, and related source characterization of the three sampling regions. DC3 also documented biomass-burning plumes and the interactions of these plumes with deep convection.

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