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  • Author or Editor: D. L. Hartmann x
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W. G. Read
,
J. W. Waters
,
D. A. Flower
,
L. Froidevaux
,
R. F. Jarnot
,
D. L. Hartmann
,
R. S. Harwood
, and
R. B. Rood

Initial results of upper-tropospheric water vapor obtained from the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) are presented. MLS is less affected by clouds than infrared or visible techniques, and the UARS orbit provides daily humidity monitoring for approximately two-thirds of the earth. Best results are currently obtained when water vapor abundances are approximately 100–300 ppmv, corresponding to approximately 12-km height in the Tropics and 7 km at high latitudes. The observed latitude variation of water vapor at 215 hPa is in good agreement with the U.K. Universities's Global Atmospheric Modelling Project model. The ability to observe synoptic-scale features associated with tropopause height variations is clearly illustrated by comparison with the National Aeronautics and Space Administration Goddard Space Flight Center assimilation model. Humidity detrainment streams extending from tropical convective regions are also observed.

Full 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