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L. L. Pan
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E. L. Atlas
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R. J. Salawitch
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S. B. Honomichl
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J. F. Bresch
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W. J. Randel
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E. C. Apel
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R. S. Hornbrook
,
A. J. Weinheimer
,
D. C. Anderson
,
S. J. Andrews
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S. Baidar
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S. P. Beaton
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T. L. Campos
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L. J. Carpenter
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D. Chen
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B. Dix
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V. Donets
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S. R. Hall
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T. F. Hanisco
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C. R. Homeyer
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L. G. Huey
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J. B. Jensen
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L. Kaser
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D. E. Kinnison
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T. K. Koenig
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J.-F. Lamarque
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C. Liu
,
J. Luo
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Z. J. Luo
,
D. D. Montzka
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J. M. Nicely
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R. B. Pierce
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D. D. Riemer
,
T. Robinson
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P. Romashkin
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A. Saiz-Lopez
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S. Schauffler
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O. Shieh
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M. H. Stell
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K. Ullmann
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G. Vaughan
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R. Volkamer
, and
G. Wolfe

Abstract

The Convective Transport of Active Species in the Tropics (CONTRAST) experiment was conducted from Guam (13.5°N, 144.8°E) during January–February 2014. Using the NSF/NCAR Gulfstream V research aircraft, the experiment investigated the photochemical environment over the tropical western Pacific (TWP) warm pool, a region of massive deep convection and the major pathway for air to enter the stratosphere during Northern Hemisphere (NH) winter. The new observations provide a wealth of information for quantifying the influence of convection on the vertical distributions of active species. The airborne in situ measurements up to 15-km altitude fill a significant gap by characterizing the abundance and altitude variation of a wide suite of trace gases. These measurements, together with observations of dynamical and microphysical parameters, provide significant new data for constraining and evaluating global chemistry–climate models. Measurements include precursor and product gas species of reactive halogen compounds that impact ozone in the upper troposphere/lower stratosphere. High-accuracy, in situ measurements of ozone obtained during CONTRAST quantify ozone concentration profiles in the upper troposphere, where previous observations from balloonborne ozonesondes were often near or below the limit of detection. CONTRAST was one of the three coordinated experiments to observe the TWP during January–February 2014. Together, CONTRAST, Airborne Tropical Tropopause Experiment (ATTREX), and Coordinated Airborne Studies in the Tropics (CAST), using complementary capabilities of the three aircraft platforms as well as ground-based instrumentation, provide a comprehensive quantification of the regional distribution and vertical structure of natural and pollutant trace gases in the TWP during NH winter, from the oceanic boundary to the lower stratosphere.

Full access
G. Vaughan
,
J. Methven
,
D. Anderson
,
B. Antonescu
,
L. Baker
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T. P. Baker
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S. P. Ballard
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K. N. Bower
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P. R. A. Brown
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J. Chagnon
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T. W. Choularton
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J. Chylik
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P. J. Connolly
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P. A. Cook
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R. J. Cotton
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J. Crosier
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C. Dearden
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J. R. Dorsey
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T. H. A. Frame
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M. W. Gallagher
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M. Goodliff
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S. L. Gray
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B. J. Harvey
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P. Knippertz
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H. W. Lean
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D. Li
,
G. Lloyd
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O. Martínez–Alvarado
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J. Nicol
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J. Norris
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E. Öström
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J. Owen
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D. J. Parker
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R. S. Plant
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I. A. Renfrew
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N. M. Roberts
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P. Rosenberg
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A. C. Rudd
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D. M. Schultz
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J. P. Taylor
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T. Trzeciak
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R. Tubbs
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A. K. Vance
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P. J. van Leeuwen
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A. Wellpott
, and
A. Woolley

Abstract

The Diabatic Influences on Mesoscale Structures in Extratropical Storms (DIAMET) project aims to improve forecasts of high-impact weather in extratropical cyclones through field measurements, high-resolution numerical modeling, and improved design of ensemble forecasting and data assimilation systems. This article introduces DIAMET and presents some of the first results. Four field campaigns were conducted by the project, one of which, in late 2011, coincided with an exceptionally stormy period marked by an unusually strong, zonal North Atlantic jet stream and a succession of severe windstorms in northwest Europe. As a result, December 2011 had the highest monthly North Atlantic Oscillation index (2.52) of any December in the last 60 years. Detailed observations of several of these storms were gathered using the U.K.’s BAe 146 research aircraft and extensive ground-based measurements. As an example of the results obtained during the campaign, observations are presented of Extratropical Cyclone Friedhelm on 8 December 2011, when surface winds with gusts exceeding 30 m s–1 crossed central Scotland, leading to widespread disruption to transportation and electricity supply. Friedhelm deepened 44 hPa in 24 h and developed a pronounced bent-back front wrapping around the storm center. The strongest winds at 850 hPa and the surface occurred in the southern quadrant of the storm, and detailed measurements showed these to be most intense in clear air between bands of showers. High-resolution ensemble forecasts from the Met Office showed similar features, with the strongest winds aligned in linear swaths between the bands, suggesting that there is potential for improved skill in forecasts of damaging winds.

Open access
Keith A. Browning
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Alan M. Blyth
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Peter A. Clark
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Ulrich Corsmeier
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Cyril J. Morcrette
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Judith L. Agnew
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Sue P. Ballard
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Dave Bamber
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Christian Barthlott
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Lindsay J. Bennett
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Karl M. Beswick
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Mark Bitter
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Karen E. Bozier
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Barbara J. Brooks
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Chris G. Collier
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Fay Davies
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Bernhard Deny
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Mark A. Dixon
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Thomas Feuerle
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Richard M. Forbes
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Catherine Gaffard
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Malcolm D. Gray
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Rolf Hankers
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Tim J. Hewison
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Norbert Kalthoff
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Samiro Khodayar
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Martin Kohler
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Christoph Kottmeier
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Stephan Kraut
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Michael Kunz
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Darcy N. Ladd
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Humphrey W. Lean
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Jürgen Lenfant
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Zhihong Li
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John Marsham
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James McGregor
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Stephan D. Mobbs
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John Nicol
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Emily Norton
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Douglas J. Parker
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Felicity Perry
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Markus Ramatschi
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Hugo M. A. Ricketts
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Nigel M. Roberts
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Andrew Russell
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Helmut Schulz
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Elizabeth C. Slack
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Geraint Vaughan
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Joe Waight
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David P. Wareing
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Robert J. Watson
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Ann R. Webb
, and
Andreas Wieser

The Convective Storm Initiation Project (CSIP) is an international project to understand precisely where, when, and how convective clouds form and develop into showers in the mainly maritime environment of southern England. A major aim of CSIP is to compare the results of the very high resolution Met Office weather forecasting model with detailed observations of the early stages of convective clouds and to use the newly gained understanding to improve the predictions of the model.

A large array of ground-based instruments plus two instrumented aircraft, from the U.K. National Centre for Atmospheric Science (NCAS) and the German Institute for Meteorology and Climate Research (IMK), Karlsruhe, were deployed in southern England, over an area centered on the meteorological radars at Chilbolton, during the summers of 2004 and 2005. In addition to a variety of ground-based remote-sensing instruments, numerous rawinsondes were released at one- to two-hourly intervals from six closely spaced sites. The Met Office weather radar network and Meteosat satellite imagery were used to provide context for the observations made by the instruments deployed during CSIP.

This article presents an overview of the CSIP field campaign and examples from CSIP of the types of convective initiation phenomena that are typical in the United Kingdom. It shows the way in which certain kinds of observational data are able to reveal these phenomena and gives an explanation of how the analyses of data from the field campaign will be used in the development of an improved very high resolution NWP model for operational use.

Full access