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A Focus On Mixed-Phase Clouds

The Status of Ground-Based Observational Methods

Matthew D. Shupe
,
John S. Daniel
,
Gijs de Boer
,
Edwin W. Eloranta
,
Pavlos Kollias
,
Charles N. Long
,
Edward P. Luke
,
David D. Turner
, and
Johannes Verlinde

The phase composition and microphysical structure of clouds define the manner in which they modulate atmospheric radiation and contribute to the hydrologic cycle. Issues regarding cloud phase partitioning and transformation come to bear directly in mixed-phase clouds, and have been difficult to address within current modeling frameworks. Ground-based, remote-sensing observations of mixed-phase clouds can contribute a significant body of knowledge with which to better understand, and thereby more accurately model, clouds and their phase-defining processes. Utilizing example observations from the Mixed-Phase Arctic Cloud Experiment (M-PACE), which occurred at the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program's Climate Research Facility in Barrow, Alaska, during autumn 2004, we review the current status of ground-based observation and retrieval methods used in characterizing the macrophysical, microphysical, radiative, and dynamical properties of stratiform mixed-phase clouds. In general, cloud phase, boundaries, ice properties, liquid water path, optical depth, and vertical velocity are available from a combination of active and passive sensors. Significant deficiencies exist in our ability to vertically characterize the liquid phase, to distinguish ice crystal habits, and to understand aerosol-cloud interactions. Further validation studies are needed to evaluate, improve, and expand our retrieval abilities in mixed-phase clouds.

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Mark S. Kulie
,
Claire Pettersen
,
Aronne J. Merrelli
,
Timothy J. Wagner
,
Norman B. Wood
,
Michael Dutter
,
David Beachler
,
Todd Kluber
,
Robin Turner
,
Marian Mateling
,
John Lenters
,
Peter Blanken
,
Maximilian Maahn
,
Christopher Spence
,
Stefan Kneifel
,
Paul A. Kucera
,
Ali Tokay
,
Larry F. Bliven
,
David B. Wolff
, and
Walter A. Petersen

Abstract

A multisensor snowfall observational suite has been deployed at the Marquette, Michigan, National Weather Service Weather Forecast Office (KMQT) since 2014. Micro Rain Radar (MRR; profiling radar), Precipitation Imaging Package (PIP; snow particle imager), and ancillary ground-based meteorological observations illustrate the unique capabilities of these combined instruments to document radar and concomitant microphysical properties associated with northern Great Lakes snowfall regimes. Lake-effect, lake-orographic, and transition event case studies are presented that illustrate the variety of snowfall events that occur at KMQT. Case studies and multiyear analyses reveal the ubiquity of snowfall produced by shallow events. These shallow snowfall features and their distinctive microphysical fingerprints are often difficult to discern with conventional remote sensing instruments, thus highlighting the scientific and potential operational value of MRR and PIP observations. The importance of near-surface lake-orographic snowfall enhancement processes in extreme snowfall events and regime-dependent snow particle microphysical variability controlled by regime and environmental factors are also highlighted.

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Gijs de Boer
,
Mark Ivey
,
Beat Schmid
,
Dale Lawrence
,
Darielle Dexheimer
,
Fan Mei
,
John Hubbe
,
Albert Bendure
,
Jasper Hardesty
,
Matthew D. Shupe
,
Allison McComiskey
,
Hagen Telg
,
Carl Schmitt
,
Sergey Y. Matrosov
,
Ian Brooks
,
Jessie Creamean
,
Amy Solomon
,
David D. Turner
,
Christopher Williams
,
Maximilian Maahn
,
Brian Argrow
,
Scott Palo
,
Charles N. Long
,
Ru-Shan Gao
, and
James Mather

Abstract

Thorough understanding of aerosols, clouds, boundary layer structure, and radiation is required to improve the representation of the Arctic atmosphere in weather forecasting and climate models. To develop such understanding, new perspectives are needed to provide details on the vertical structure and spatial variability of key atmospheric properties, along with information over difficult-to-reach surfaces such as newly forming sea ice. Over the last three years, the U.S. Department of Energy (DOE) has supported various flight campaigns using unmanned aircraft systems [UASs, also known as unmanned aerial vehicles (UAVs) and drones] and tethered balloon systems (TBSs) at Oliktok Point, Alaska. These activities have featured in situ measurements of the thermodynamic state, turbulence, radiation, aerosol properties, cloud microphysics, and turbulent fluxes to provide a detailed characterization of the lower atmosphere. Alongside a suite of active and passive ground-based sensors and radiosondes deployed by the DOE Atmospheric Radiation Measurement (ARM) program through the third ARM Mobile Facility (AMF-3), these flight activities demonstrate the ability of such platforms to provide critically needed information. In addition to providing new and unique datasets, lessons learned during initial campaigns have assisted in the development of an exciting new community resource.

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Andrew M. Vogelmann
,
Greg M. McFarquhar
,
John A. Ogren
,
David D. Turner
,
Jennifer M. Comstock
,
Graham Feingold
,
Charles N. Long
,
Haflidi H. Jonsson
,
Anthony Bucholtz
,
Don R. Collins
,
Glenn S. Diskin
,
Hermann Gerber
,
R. Paul Lawson
,
Roy K. Woods
,
Elisabeth Andrews
,
Hee-Jung Yang
,
J. Christine Chiu
,
Daniel Hartsock
,
John M. Hubbe
,
Chaomei Lo
,
Alexander Marshak
,
Justin W. Monroe
,
Sally A. McFarlane
,
Beat Schmid
,
Jason M. Tomlinson
, and
Tami Toto

A first-of-a-kind, extended-term cloud aircraft campaign was conducted to obtain an in situ statistical characterization of continental boundary layer clouds needed to investigate cloud processes and refine retrieval algorithms. Coordinated by the Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF), the Routine AAF Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations (RACORO) field campaign operated over the ARM Southern Great Plains (SGP) site from 22 January to 30 June 2009, collecting 260 h of data during 59 research flights. A comprehensive payload aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft measured cloud microphysics, solar and thermal radiation, physical aerosol properties, and atmospheric state parameters. Proximity to the SGP's extensive complement of surface measurements provides ancillary data that support modeling studies and facilitates evaluation of a variety of surface retrieval algorithms. The five-month duration enabled sampling a range of conditions associated with the seasonal transition from winter to summer. Although about twothirds of the flights during which clouds were sampled occurred in May and June, boundary layer cloud fields were sampled under a variety of environmental and aerosol conditions, with about 77% of the cloud flights occurring in cumulus and stratocumulus. Preliminary analyses illustrate use of these data to analyze aerosol– cloud relationships, characterize the horizontal variability of cloud radiative impacts, and evaluate surface-based retrievals. We discuss how an extended-term campaign requires a simplified operating paradigm that is different from that used for typical, short-term, intensive aircraft field programs.

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Joseph B. Olson
,
Jaymes S. Kenyon
,
Irina Djalalova
,
Laura Bianco
,
David D. Turner
,
Yelena Pichugina
,
Aditya Choukulkar
,
Michael D. Toy
,
John M. Brown
,
Wayne M. Angevine
,
Elena Akish
,
Jian-Wen Bao
,
Pedro Jimenez
,
Branko Kosovic
,
Katherine A. Lundquist
,
Caroline Draxl
,
Julie K. Lundquist
,
Jim McCaa
,
Katherine McCaffrey
,
Kathy Lantz
,
Chuck Long
,
Jim Wilczak
,
Robert Banta
,
Melinda Marquis
,
Stephanie Redfern
,
Larry K. Berg
,
Will Shaw
, and
Joel Cline

Abstract

The primary goal of the Second Wind Forecast Improvement Project (WFIP2) is to advance the state-of-the-art of wind energy forecasting in complex terrain. To achieve this goal, a comprehensive 18-month field measurement campaign was conducted in the region of the Columbia River basin. The observations were used to diagnose and quantify systematic forecast errors in the operational High-Resolution Rapid Refresh (HRRR) model during weather events of particular concern to wind energy forecasting. Examples of such events are cold pools, gap flows, thermal troughs/marine pushes, mountain waves, and topographic wakes. WFIP2 model development has focused on the boundary layer and surface-layer schemes, cloud–radiation interaction, the representation of drag associated with subgrid-scale topography, and the representation of wind farms in the HRRR. Additionally, refinements to numerical methods have helped to improve some of the common forecast error modes, especially the high wind speed biases associated with early erosion of mountain–valley cold pools. This study describes the model development and testing undertaken during WFIP2 and demonstrates forecast improvements. Specifically, WFIP2 found that mean absolute errors in rotor-layer wind speed forecasts could be reduced by 5%–20% in winter by improving the turbulent mixing lengths, horizontal diffusion, and gravity wave drag. The model improvements made in WFIP2 are also shown to be applicable to regions outside of complex terrain. Ongoing and future challenges in model development will also be discussed.

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Taneil Uttal
,
Sandra Starkweather
,
James R. Drummond
,
Timo Vihma
,
Alexander P. Makshtas
,
Lisa S. Darby
,
John F. Burkhart
,
Christopher J. Cox
,
Lauren N. Schmeisser
,
Thomas Haiden
,
Marion Maturilli
,
Matthew D. Shupe
,
Gijs De Boer
,
Auromeet Saha
,
Andrey A. Grachev
,
Sara M. Crepinsek
,
Lori Bruhwiler
,
Barry Goodison
,
Bruce McArthur
,
Von P. Walden
,
Edward J. Dlugokencky
,
P. Ola G. Persson
,
Glen Lesins
,
Tuomas Laurila
,
John A. Ogren
,
Robert Stone
,
Charles N. Long
,
Sangeeta Sharma
,
Andreas Massling
,
David D. Turner
,
Diane M. Stanitski
,
Eija Asmi
,
Mika Aurela
,
Henrik Skov
,
Konstantinos Eleftheriadis
,
Aki Virkkula
,
Andrew Platt
,
Eirik J. Førland
,
Yoshihiro Iijima
,
Ingeborg E. Nielsen
,
Michael H. Bergin
,
Lauren Candlish
,
Nikita S. Zimov
,
Sergey A. Zimov
,
Norman T. O’Neill
,
Pierre F. Fogal
,
Rigel Kivi
,
Elena A. Konopleva-Akish
,
Johannes Verlinde
,
Vasily Y. Kustov
,
Brian Vasel
,
Viktor M. Ivakhov
,
Yrjö Viisanen
, and
Janet M. Intrieri

Abstract

International Arctic Systems for Observing the Atmosphere (IASOA) activities and partnerships were initiated as a part of the 2007–09 International Polar Year (IPY) and are expected to continue for many decades as a legacy program. The IASOA focus is on coordinating intensive measurements of the Arctic atmosphere collected in the United States, Canada, Russia, Norway, Finland, and Greenland to create synthesis science that leads to an understanding of why and not just how the Arctic atmosphere is evolving. The IASOA premise is that there are limitations with Arctic modeling and satellite observations that can only be addressed with boots-on-the-ground, in situ observations and that the potential of combining individual station and network measurements into an integrated observing system is tremendous. The IASOA vision is that by further integrating with other network observing programs focusing on hydrology, glaciology, oceanography, terrestrial, and biological systems it will be possible to understand the mechanisms of the entire Arctic system, perhaps well enough for humans to mitigate undesirable variations and adapt to inevitable change.

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Bart Geerts
,
David Parsons
,
Conrad L. Ziegler
,
Tammy M. Weckwerth
,
Michael I. Biggerstaff
,
Richard D. Clark
,
Michael C. Coniglio
,
Belay B. Demoz
,
Richard A. Ferrare
,
William A. Gallus Jr.
,
Kevin Haghi
,
John M. Hanesiak
,
Petra M. Klein
,
Kevin R. Knupp
,
Karen Kosiba
,
Greg M. McFarquhar
,
James A. Moore
,
Amin R. Nehrir
,
Matthew D. Parker
,
James O. Pinto
,
Robert M. Rauber
,
Russ S. Schumacher
,
David D. Turner
,
Qing Wang
,
Xuguang Wang
,
Zhien Wang
, and
Joshua Wurman

Abstract

The central Great Plains region in North America has a nocturnal maximum in warm-season precipitation. Much of this precipitation comes from organized mesoscale convective systems (MCSs). This nocturnal maximum is counterintuitive in the sense that convective activity over the Great Plains is out of phase with the local generation of CAPE by solar heating of the surface. The lower troposphere in this nocturnal environment is typically characterized by a low-level jet (LLJ) just above a stable boundary layer (SBL), and convective available potential energy (CAPE) values that peak above the SBL, resulting in convection that may be elevated, with source air decoupled from the surface. Nocturnal MCS-induced cold pools often trigger undular bores and solitary waves within the SBL. A full understanding of the nocturnal precipitation maximum remains elusive, although it appears that bore-induced lifting and the LLJ may be instrumental to convection initiation and the maintenance of MCSs at night.

To gain insight into nocturnal MCSs, their essential ingredients, and paths toward improving the relatively poor predictive skill of nocturnal convection in weather and climate models, a large, multiagency field campaign called Plains Elevated Convection At Night (PECAN) was conducted in 2015. PECAN employed three research aircraft, an unprecedented coordinated array of nine mobile scanning radars, a fixed S-band radar, a unique mesoscale network of lower-tropospheric profiling systems called the PECAN Integrated Sounding Array (PISA), and numerous mobile-mesonet surface weather stations. The rich PECAN dataset is expected to improve our understanding and prediction of continental nocturnal warm-season precipitation. This article provides a summary of the PECAN field experiment and preliminary findings.

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Indirect and Semi-direct Aerosol Campaign

The Impact of Arctic Aerosols on Clouds

Greg M. McFarquhar
,
Steven Ghan
,
Johannes Verlinde
,
Alexei Korolev
,
J. Walter Strapp
,
Beat Schmid
,
Jason M. Tomlinson
,
Mengistu Wolde
,
Sarah D. Brooks
,
Dan Cziczo
,
Manvendra K. Dubey
,
Jiwen Fan
,
Connor Flynn
,
Ismail Gultepe
,
John Hubbe
,
Mary K. Gilles
,
Alexander Laskin
,
Paul Lawson
,
W. Richard Leaitch
,
Peter Liu
,
Xiaohong Liu
,
Dan Lubin
,
Claudio Mazzoleni
,
Ann-Marie Macdonald
,
Ryan C. Moffet
,
Hugh Morrison
,
Mikhail Ovchinnikov
,
Matthew D. Shupe
,
David D. Turner
,
Shaocheng Xie
,
Alla Zelenyuk
,
Kenny Bae
,
Matt Freer
, and
Andrew Glen

Abstract

A comprehensive dataset of microphysical and radiative properties of aerosols and clouds in the boundary layer in the vicinity of Barrow, Alaska, was collected in April 2008 during the Indirect and Semi-Direct Aerosol Campaign (ISDAC). ISDAC's primary aim was to examine the effects of aerosols, including those generated by Asian wildfires, on clouds that contain both liquid and ice. ISDAC utilized the Atmospheric Radiation Measurement Pro- gram's permanent observational facilities at Barrow and specially deployed instruments measuring aerosol, ice fog, precipitation, and radiation. The National Research Council of Canada Convair-580 flew 27 sorties and collected data using an unprecedented 41 stateof- the-art cloud and aerosol instruments for more than 100 h on 12 different days. Aerosol compositions, including fresh and processed sea salt, biomassburning particles, organics, and sulfates mixed with organics, varied between flights. Observations in a dense arctic haze on 19 April and above, within, and below the single-layer stratocumulus on 8 and 26 April are enabling a process-oriented understanding of how aerosols affect arctic clouds. Inhomogeneities in reflectivity, a close coupling of upward and downward Doppler motion, and a nearly constant ice profile in the single-layer stratocumulus suggests that vertical mixing is responsible for its longevity observed during ISDAC. Data acquired in cirrus on flights between Barrow and Fairbanks, Alaska, are improving the understanding of the performance of cloud probes in ice. Ultimately, ISDAC data will improve the representation of cloud and aerosol processes in models covering a variety of spatial and temporal scales, and determine the extent to which surface measurements can provide retrievals of aerosols, clouds, precipitation, and radiative heating.

A supplement to this article is available online:

DOI: 10.1175/2010BAMS2935.2

Full access
Diana Greenslade
,
Mark Hemer
,
Alex Babanin
,
Ryan Lowe
,
Ian Turner
,
Hannah Power
,
Ian Young
,
Daniel Ierodiaconou
,
Greg Hibbert
,
Greg Williams
,
Saima Aijaz
,
João Albuquerque
,
Stewart Allen
,
Michael Banner
,
Paul Branson
,
Steve Buchan
,
Andrew Burton
,
John Bye
,
Nick Cartwright
,
Amin Chabchoub
,
Frank Colberg
,
Stephanie Contardo
,
Francois Dufois
,
Craig Earl-Spurr
,
David Farr
,
Ian Goodwin
,
Jim Gunson
,
Jeff Hansen
,
David Hanslow
,
Mitchell Harley
,
Yasha Hetzel
,
Ron Hoeke
,
Nicole Jones
,
Michael Kinsela
,
Qingxiang Liu
,
Oleg Makarynskyy
,
Hayden Marcollo
,
Said Mazaheri
,
Jason McConochie
,
Grant Millar
,
Tim Moltmann
,
Neal Moodie
,
Joao Morim
,
Russel Morison
,
Jana Orszaghova
,
Charitha Pattiaratchi
,
Andrew Pomeroy
,
Roger Proctor
,
David Provis
,
Ruth Reef
,
Dirk Rijnsdorp
,
Martin Rutherford
,
Eric Schulz
,
Jake Shayer
,
Kristen Splinter
,
Craig Steinberg
,
Darrell Strauss
,
Greg Stuart
,
Graham Symonds
,
Karina Tarbath
,
Daniel Taylor
,
James Taylor
,
Darshani Thotagamuwage
,
Alessandro Toffoli
,
Alireza Valizadeh
,
Jonathan van Hazel
,
Guilherme Vieira da Silva
,
Moritz Wandres
,
Colin Whittaker
,
David Williams
,
Gundula Winter
,
Jiangtao Xu
,
Aihong Zhong
, and
Stefan Zieger

Abstract

The Australian marine research, industry, and stakeholder community has recently undertaken an extensive collaborative process to identify the highest national priorities for wind-waves research. This was undertaken under the auspices of the Forum for Operational Oceanography Surface Waves Working Group. The main steps in the process were first, soliciting possible research questions from the community via an online survey; second, reviewing the questions at a face-to-face workshop; and third, online ranking of the research questions by individuals. This process resulted in 15 identified priorities, covering research activities and the development of infrastructure. The top five priorities are 1) enhanced and updated nearshore and coastal bathymetry; 2) improved understanding of extreme sea states; 3) maintain and enhance the in situ buoy network; 4) improved data access and sharing; and 5) ensemble and probabilistic wave modeling and forecasting. In this paper, each of the 15 priorities is discussed in detail, providing insight into why each priority is important, and the current state of the art, both nationally and internationally, where relevant. While this process has been driven by Australian needs, it is likely that the results will be relevant to other marine-focused nations.

Free access
Diana Greenslade
,
Mark Hemer
,
Alex Babanin
,
Ryan Lowe
,
Ian Turner
,
Hannah Power
,
Ian Young
,
Daniel Ierodiaconou
,
Greg Hibbert
,
Greg Williams
,
Saima Aijaz
,
João Albuquerque
,
Stewart Allen
,
Michael Banner
,
Paul Branson
,
Steve Buchan
,
Andrew Burton
,
John Bye
,
Nick Cartwright
,
Amin Chabchoub
,
Frank Colberg
,
Stephanie Contardo
,
Francois Dufois
,
Craig Earl-Spurr
,
David Farr
,
Ian Goodwin
,
Jim Gunson
,
Jeff Hansen
,
David Hanslow
,
Mitchell Harley
,
Yasha Hetzel
,
Ron Hoeke
,
Nicole Jones
,
Michael Kinsela
,
Qingxiang Liu
,
Oleg Makarynskyy
,
Hayden Marcollo
,
Said Mazaheri
,
Jason McConochie
,
Grant Millar
,
Tim Moltmann
,
Neal Moodie
,
Joao Morim
,
Russel Morison
,
Jana Orszaghova
,
Charitha Pattiaratchi
,
Andrew Pomeroy
,
Roger Proctor
,
David Provis
,
Ruth Reef
,
Dirk Rijnsdorp
,
Martin Rutherford
,
Eric Schulz
,
Jake Shayer
,
Kristen Splinter
,
Craig Steinberg
,
Darrell Strauss
,
Greg Stuart
,
Graham Symonds
,
Karina Tarbath
,
Daniel Taylor
,
James Taylor
,
Darshani Thotagamuwage
,
Alessandro Toffoli
,
Alireza Valizadeh
,
Jonathan van Hazel
,
Guilherme Vieira da Silva
,
Moritz Wandres
,
Colin Whittaker
,
David Williams
,
Gundula Winter
,
Jiangtao Xu
,
Aihong Zhong
, and
Stefan Zieger
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