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Steven B. Alejandro
,
George G. Koenig
,
J. Michael Vaughan
, and
P. Hywel Davies

The plans for an atmospheric aerosol field measurement experiment are described. The South Atlantic Backscatter Lidar Experiment (SABLE) is an important step in determining the feasibility of obtaining space-based lidar measurements for the determination of atmospheric winds, and the spatial and temporal variation of aerosol backscatter. Two field campaigns operating from Ascension Island (a British colony of St. Helena) have been completed. The first field campaign obtained lidar backscatter measurements utilizing an airborne platform during a 3-week period from mid-October through mid-November 1988. The second SABLE program was expanded to include measurements utilizing airborne particle-measurement probes, ground-based lidars, radiosondes, and supporting meteorological equipment. This program was conducted during a 4-week period from mid-June through mid-July 1989. This is the first time that such a comprehensive, aerosol-measurement program has been undertaken in the Southern Hemisphere. SABLE-type measurements are not only pertinent to the development of space-based sensors, but also have direct utility in the study of aerosols and their effect on climate.

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Peter T. May
,
James H. Mather
,
Geraint Vaughan
,
Keith N. Bower
,
Christian Jakob
,
Greg M. McFarquhar
, and
Gerald G. Mace
Full access
Peter T. May
,
James H. Mather
,
Geraint Vaughan
,
Christian Jakob
,
Greg M. McFarquhar
,
Keith N. Bower
, and
Gerald G. Mace

A comprehensive dataset describing tropical cloud systems and their environmental setting and impacts has been collected during the Tropical Warm Pool International Cloud Experiment (TWPICE) and Aerosol and Chemical Transport in Tropical Convection (ACTIVE) campaign in the area around Darwin, Northern Australia, in January and February 2006. The aim of the experiment was to observe the evolution of tropical cloud systems and their interaction with the environment within an observational framework optimized for a range of modeling activities with the goal of improving the representation of cloud and aerosol process in a range of models. The experiment design utilized permanent observational facilities in Darwin, including a polarimetric weather radar and a suite of cloud remote-sensing instruments. This was augmented by a dense network of soundings, together with radiation, flux, lightning, and remote-sensing measurements, as well as oceanographic observations. A fleet of five research aircraft, including two high-altitude aircraft, were taking measurements of fluxes, cloud microphysics, and chemistry; cloud radar and lidar were carried on a third aircraft. Highlights of the experiment include an intense mesoscale convective system (MCS) developed within the network, observations used to analyze the impacts of aerosol on convective systems, and observations used to relate cirrus properties to the parent storm properties.

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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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F. R. Robertson
,
G. S. Wilson
,
H. J. Christian Jr.
,
S. J. Goodman
,
G. H. Fichtl
, and
W. W. Vaughan

The present lack of a lower atmosphere research satellite program for the 1980s has prompted consideration of the Space Shuttle/Spacelab system as a means of flying sensor complements geared toward specific research problems, as well as continued instrument development. Three specific examples of possible science questions related to precipitation are discussed: 1) spatial structure of mesoscale cloud and precipitation systems, 2) lightning and storm development, and 3) cyclone intensification over oceanic regions. Examples of space sensors available to provide measurements needed in addressing these questions are also presented. Distinctive aspects of low-earth orbit experiments would be high resolution, multispectral sensing of atmospheric phenomena by complements of instruments, and more efficient sensor development through reflights of specific hardware packages.

Full access
N. R. P. Harris
,
L. J. Carpenter
,
J. D. Lee
,
G. Vaughan
,
M. T. Filus
,
R. L. Jones
,
B. OuYang
,
J. A. Pyle
,
A. D. Robinson
,
S. J. Andrews
,
A. C. Lewis
,
J. Minaeian
,
A. Vaughan
,
J. R. Dorsey
,
M. W. Gallagher
,
M. Le Breton
,
R. Newton
,
C. J. Percival
,
H. M. A. Ricketts
,
S. J.-B. Bauguitte
,
G. J. Nott
,
A. Wellpott
,
M. J. Ashfold
,
J. Flemming
,
R. Butler
,
P. I. Palmer
,
P. H. Kaye
,
C. Stopford
,
C. Chemel
,
H. Boesch
,
N. Humpage
,
A. Vick
,
A. R. MacKenzie
,
R. Hyde
,
P. Angelov
,
E. Meneguz
, and
A. J. Manning

Abstract

The main field activities of the Coordinated Airborne Studies in the Tropics (CAST) campaign took place in the west Pacific during January–February 2014. The field campaign was based in Guam (13.5°N, 144.8°E), using the U.K. Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 atmospheric research aircraft, and was coordinated with the Airborne Tropical Tropopause Experiment (ATTREX) project with an unmanned Global Hawk and the Convective Transport of Active Species in the Tropics (CONTRAST) campaign with a Gulfstream V aircraft. Together, the three aircraft were able to make detailed measurements of atmospheric structure and composition from the ocean surface to 20 km. These measurements are providing new information about the processes influencing halogen and ozone levels in the tropical west Pacific, as well as the importance of trace-gas transport in convection for the upper troposphere and stratosphere. The FAAM aircraft made a total of 25 flights in the region between 1°S and 14°N and 130° and 155°E. It was used to sample at altitudes below 8 km, with much of the time spent in the marine boundary layer. It measured a range of chemical species and sampled extensively within the region of main inflow into the strong west Pacific convection. The CAST team also made ground-based measurements of a number of species (including daily ozonesondes) at the Atmospheric Radiation Measurement Program site on Manus Island, Papua New Guinea (2.1°S, 147.4°E). This article presents an overview of the CAST project, focusing on the design and operation of the west Pacific experiment. It additionally discusses some new developments in CAST, including flights of new instruments on board the Global Hawk in February–March 2015.

Open access

The CALIPSO Mission

A Global 3D View of Aerosols and Clouds

D. M. Winker
,
J. Pelon
,
J. A. Coakley Jr.
,
S. A. Ackerman
,
R. J. Charlson
,
P. R. Colarco
,
P. Flamant
,
Q. Fu
,
R. M. Hoff
,
C. Kittaka
,
T. L. Kubar
,
H. Le Treut
,
M. P. Mccormick
,
G. Mégie
,
L. Poole
,
K. Powell
,
C. Trepte
,
M. A. Vaughan
, and
B. A. Wielicki

Aerosols and clouds have important effects on Earth's climate through their effects on the radiation budget and the cycling of water between the atmosphere and Earth's surface. Limitations in our understanding of the global distribution and properties of aerosols and clouds are partly responsible for the current uncertainties in modeling the global climate system and predicting climate change. The CALIPSO satellite was developed as a joint project between NASA and the French space agency CNES to provide needed capabilities to observe aerosols and clouds from space. CALIPSO carries CALIOP, a two-wavelength, polarization-sensitive lidar, along with two passive sensors operating in the visible and thermal infrared spectral regions. CALIOP is the first lidar to provide long-term atmospheric measurements from Earth's orbit. Its profiling and polarization capabilities offer unique measurement capabilities. Launched together with the CloudSat satellite in April 2006 and now flying in formation with the A-train satellite constellation, CALIPSO is now providing information on the distribution and properties of aerosols and clouds, which is fundamental to advancing our understanding and prediction of climate. This paper provides an overview of the CALIPSO mission and instruments, the data produced, and early results.

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

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Keith A. Browning
,
Alan M. Blyth
,
Peter A. Clark
,
Ulrich Corsmeier
,
Cyril J. Morcrette
,
Judith L. Agnew
,
Sue P. Ballard
,
Dave Bamber
,
Christian Barthlott
,
Lindsay J. Bennett
,
Karl M. Beswick
,
Mark Bitter
,
Karen E. Bozier
,
Barbara J. Brooks
,
Chris G. Collier
,
Fay Davies
,
Bernhard Deny
,
Mark A. Dixon
,
Thomas Feuerle
,
Richard M. Forbes
,
Catherine Gaffard
,
Malcolm D. Gray
,
Rolf Hankers
,
Tim J. Hewison
,
Norbert Kalthoff
,
Samiro Khodayar
,
Martin Kohler
,
Christoph Kottmeier
,
Stephan Kraut
,
Michael Kunz
,
Darcy N. Ladd
,
Humphrey W. Lean
,
Jürgen Lenfant
,
Zhihong Li
,
John Marsham
,
James McGregor
,
Stephan D. Mobbs
,
John Nicol
,
Emily Norton
,
Douglas J. Parker
,
Felicity Perry
,
Markus Ramatschi
,
Hugo M. A. Ricketts
,
Nigel M. Roberts
,
Andrew Russell
,
Helmut Schulz
,
Elizabeth C. Slack
,
Geraint Vaughan
,
Joe Waight
,
David P. Wareing
,
Robert J. Watson
,
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
G. Vaughan
,
J. Methven
,
D. Anderson
,
B. Antonescu
,
L. Baker
,
T. P. Baker
,
S. P. Ballard
,
K. N. Bower
,
P. R. A. Brown
,
J. Chagnon
,
T. W. Choularton
,
J. Chylik
,
P. J. Connolly
,
P. A. Cook
,
R. J. Cotton
,
J. Crosier
,
C. Dearden
,
J. R. Dorsey
,
T. H. A. Frame
,
M. W. Gallagher
,
M. Goodliff
,
S. L. Gray
,
B. J. Harvey
,
P. Knippertz
,
H. W. Lean
,
D. Li
,
G. Lloyd
,
O. Martínez–Alvarado
,
J. Nicol
,
J. Norris
,
E. Öström
,
J. Owen
,
D. J. Parker
,
R. S. Plant
,
I. A. Renfrew
,
N. M. Roberts
,
P. Rosenberg
,
A. C. Rudd
,
D. M. Schultz
,
J. P. Taylor
,
T. Trzeciak
,
R. Tubbs
,
A. K. Vance
,
P. J. van Leeuwen
,
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