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Ch Werner
and
H. Herrmann

Abstract

A description is given of a ruby lidar, differential absorption system developed for the measurement of absolute humidity profiles in the atmospheric boundary layer. Two independent temperature controlled ruby lasers are used as transmitters and the backscattered signal from each is digitized and stored separately. Prior to use, the system was calibrated over a horizontal path. Profiles of the absolute humidity have been obtained with a vertical range resolution of 100 m and these are discussed in comparison with radiosonde and airborne measurements.

Full access
Christian Stolle
,
Mariana Ribas-Ribas
,
Thomas H. Badewien
,
Jonathan Barnes
,
Lucy J. Carpenter
,
Rosie Chance
,
Lars Riis Damgaard
,
Ana María Durán Quesada
,
Anja Engel
,
Sanja Frka
,
Luisa Galgani
,
Blaženka Gašparović
,
Michaela Gerriets
,
Nur Ili Hamizah Mustaffa
,
Hartmut Herrmann
,
Liisa Kallajoki
,
Ryan Pereira
,
Franziska Radach
,
Niels Peter Revsbech
,
Philippa Rickard
,
Adam Saint
,
Matthew Salter
,
Maren Striebel
,
Nadja Triesch
,
Guenther Uher
,
Robert C. Upstill-Goddard
,
Manuela van Pinxteren
,
Birthe Zäncker
,
Paul Zieger
, and
Oliver Wurl
Full access
Christian Stolle
,
Mariana Ribas-Ribas
,
Thomas H. Badewien
,
Jonathan Barnes
,
Lucy J. Carpenter
,
Rosie Chance
,
Lars Riis Damgaard
,
Ana María Durán Quesada
,
Anja Engel
,
Sanja Frka
,
Luisa Galgani
,
Blaženka Gašparović
,
Michaela Gerriets
,
Nur Ili Hamizah Mustaffa
,
Hartmut Herrmann
,
Liisa Kallajoki
,
Ryan Pereira
,
Franziska Radach
,
Niels Peter Revsbech
,
Philippa Rickard
,
Adam Saint
,
Matthew Salter
,
Maren Striebel
,
Nadja Triesch
,
Guenther Uher
,
Robert C. Upstill-Goddard
,
Manuela van Pinxteren
,
Birthe Zäncker
,
Paul Zieger
, and
Oliver Wurl

Abstract

The sea surface microlayer (SML) at the air–sea interface is <1 mm thick, but it is physically, chemically, and biologically distinct from the underlying water and the atmosphere above. Wind-driven turbulence and solar radiation are important drivers of SML physical and biogeochemical properties. Given that the SML is involved in all air–sea exchanges of mass and energy, its response to solar radiation, especially in relation to how it regulates the air–sea exchange of climate-relevant gases and aerosols, is surprisingly poorly characterized. MILAN (Sea Surface Microlayer at Night) was an international, multidisciplinary campaign designed to specifically address this issue. In spring 2017, we deployed diverse sampling platforms (research vessels, radio-controlled catamaran, free-drifting buoy) to study full diel cycles in the coastal North Sea SML and in underlying water, and installed a land-based aerosol sampler. We also carried out concurrent ex situ experiments using several microsensors, a laboratory gas exchange tank, a solar simulator, and a sea spray simulation chamber. In this paper we outline the diversity of approaches employed and some initial results obtained during MILAN. Our observations of diel SML variability show, for example, an influence of (i) changing solar radiation on the quantity and quality of organic material and (ii) diel changes in wind intensity primarily forcing air–sea CO2 exchange. Thus, MILAN underlines the value and the need of multidiciplinary campaigns for integrating SML complexity into the context of air–sea interaction.

Free access
M. Wendisch
,
M. Brückner
,
S. Crewell
,
A. Ehrlich
,
J. Notholt
,
C. Lüpkes
,
A. Macke
,
J. P. Burrows
,
A. Rinke
,
J. Quaas
,
M. Maturilli
,
V. Schemann
,
M. D. Shupe
,
E. F. Akansu
,
C. Barrientos-Velasco
,
K. Bärfuss
,
A.-M. Blechschmidt
,
K. Block
,
I. Bougoudis
,
H. Bozem
,
C. Böckmann
,
A. Bracher
,
H. Bresson
,
L. Bretschneider
,
M. Buschmann
,
D. G. Chechin
,
J. Chylik
,
S. Dahlke
,
H. Deneke
,
K. Dethloff
,
T. Donth
,
W. Dorn
,
R. Dupuy
,
K. Ebell
,
U. Egerer
,
R. Engelmann
,
O. Eppers
,
R. Gerdes
,
R. Gierens
,
I. V. Gorodetskaya
,
M. Gottschalk
,
H. Griesche
,
V. M. Gryanik
,
D. Handorf
,
B. Harm-Altstädter
,
J. Hartmann
,
M. Hartmann
,
B. Heinold
,
A. Herber
,
H. Herrmann
,
G. Heygster
,
I. Höschel
,
Z. Hofmann
,
J. Hölemann
,
A. Hünerbein
,
S. Jafariserajehlou
,
E. Jäkel
,
C. Jacobi
,
M. Janout
,
F. Jansen
,
O. Jourdan
,
Z. Jurányi
,
H. Kalesse-Los
,
T. Kanzow
,
R. Käthner
,
L. L. Kliesch
,
M. Klingebiel
,
E. M. Knudsen
,
T. Kovács
,
W. Körtke
,
D. Krampe
,
J. Kretzschmar
,
D. Kreyling
,
B. Kulla
,
D. Kunkel
,
A. Lampert
,
M. Lauer
,
L. Lelli
,
A. von Lerber
,
O. Linke
,
U. Löhnert
,
M. Lonardi
,
S. N. Losa
,
M. Losch
,
M. Maahn
,
M. Mech
,
L. Mei
,
S. Mertes
,
E. Metzner
,
D. Mewes
,
J. Michaelis
,
G. Mioche
,
M. Moser
,
K. Nakoudi
,
R. Neggers
,
R. Neuber
,
T. Nomokonova
,
J. Oelker
,
I. Papakonstantinou-Presvelou
,
F. Pätzold
,
V. Pefanis
,
C. Pohl
,
M. van Pinxteren
,
A. Radovan
,
M. Rhein
,
M. Rex
,
A. Richter
,
N. Risse
,
C. Ritter
,
P. Rostosky
,
V. V. Rozanov
,
E. Ruiz Donoso
,
P. Saavedra Garfias
,
M. Salzmann
,
J. Schacht
,
M. Schäfer
,
J. Schneider
,
N. Schnierstein
,
P. Seifert
,
S. Seo
,
H. Siebert
,
M. A. Soppa
,
G. Spreen
,
I. S. Stachlewska
,
J. Stapf
,
F. Stratmann
,
I. Tegen
,
C. Viceto
,
C. Voigt
,
M. Vountas
,
A. Walbröl
,
M. Walter
,
B. Wehner
,
H. Wex
,
S. Willmes
,
M. Zanatta
, and
S. Zeppenfeld

Abstract

Mechanisms behind the phenomenon of Arctic amplification are widely discussed. To contribute to this debate, the (AC)3 project was established in 2016 (www.ac3-tr.de/). It comprises modeling and data analysis efforts as well as observational elements. The project has assembled a wealth of ground-based, airborne, shipborne, and satellite data of physical, chemical, and meteorological properties of the Arctic atmosphere, cryosphere, and upper ocean that are available for the Arctic climate research community. Short-term changes and indications of long-term trends in Arctic climate parameters have been detected using existing and new data. For example, a distinct atmospheric moistening, an increase of regional storm activities, an amplified winter warming in the Svalbard and North Pole regions, and a decrease of sea ice thickness in the Fram Strait and of snow depth on sea ice have been identified. A positive trend of tropospheric bromine monoxide (BrO) column densities during polar spring was verified. Local marine/biogenic sources for cloud condensation nuclei and ice nucleating particles were found. Atmospheric–ocean and radiative transfer models were advanced by applying new parameterizations of surface albedo, cloud droplet activation, convective plumes and related processes over leads, and turbulent transfer coefficients for stable surface layers. Four modes of the surface radiative energy budget were explored and reproduced by simulations. To advance the future synthesis of the results, cross-cutting activities are being developed aiming to answer key questions in four focus areas: lapse rate feedback, surface processes, Arctic mixed-phase clouds, and airmass transport and transformation.

Open access