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Andrey Y. Shcherbina
,
Miles A. Sundermeyer
,
Eric Kunze
,
Eric D’Asaro
,
Gualtiero Badin
,
Daniel Birch
,
Anne-Marie E. G. Brunner-Suzuki
,
Jörn Callies
,
Brandy T. Kuebel Cervantes
,
Mariona Claret
,
Brian Concannon
,
Jeffrey Early
,
Raffaele Ferrari
,
Louis Goodman
,
Ramsey R. Harcourt
,
Jody M. Klymak
,
Craig M. Lee
,
M.-Pascale Lelong
,
Murray D. Levine
,
Ren-Chieh Lien
,
Amala Mahadevan
,
James C. McWilliams
,
M. Jeroen Molemaker
,
Sonaljit Mukherjee
,
Jonathan D. Nash
,
Tamay Özgökmen
,
Stephen D. Pierce
,
Sanjiv Ramachandran
,
Roger M. Samelson
,
Thomas B. Sanford
,
R. Kipp Shearman
,
Eric D. Skyllingstad
,
K. Shafer Smith
,
Amit Tandon
,
John R. Taylor
,
Eugene A. Terray
,
Leif N. Thomas
, and
James R. Ledwell

Abstract

Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy stirring at scales on the order of 100 km (the mesoscale) is fairly well understood and explicitly represented in modern eddy-resolving numerical models of global ocean circulation. The same cannot be said for smaller-scale stirring processes. Here, the authors describe a major oceanographic field experiment aimed at observing and understanding the processes responsible for stirring at scales of 0.1–10 km. Stirring processes of varying intensity were studied in the Sargasso Sea eddy field approximately 250 km southeast of Cape Hatteras. Lateral variability of water-mass properties, the distribution of microscale turbulence, and the evolution of several patches of inert dye were studied with an array of shipboard, autonomous, and airborne instruments. Observations were made at two sites, characterized by weak and moderate background mesoscale straining, to contrast different regimes of lateral stirring. Analyses to date suggest that, in both cases, the lateral dispersion of natural and deliberately released tracers was O(1) m2 s–1 as found elsewhere, which is faster than might be expected from traditional shear dispersion by persistent mesoscale flow and linear internal waves. These findings point to the possible importance of kilometer-scale stirring by submesoscale eddies and nonlinear internal-wave processes or the need to modify the traditional shear-dispersion paradigm to include higher-order effects. A unique aspect of the Scalable Lateral Mixing and Coherent Turbulence (LatMix) field experiment is the combination of direct measurements of dye dispersion with the concurrent multiscale hydrographic and turbulence observations, enabling evaluation of the underlying mechanisms responsible for the observed dispersion at a new level.

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
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
Catherine A. Senior
,
John H. Marsham
,
Ségolène Berthou
,
Laura E. Burgin
,
Sonja S. Folwell
,
Elizabeth J. Kendon
,
Cornelia M. Klein
,
Richard G. Jones
,
Neha Mittal
,
David P. Rowell
,
Lorenzo Tomassini
,
Théo Vischel
,
Bernd Becker
,
Cathryn E. Birch
,
Julia Crook
,
Andrew J. Dougill
,
Declan L. Finney
,
Richard J. Graham
,
Neil C. G. Hart
,
Christopher D. Jack
,
Lawrence S. Jackson
,
Rachel James
,
Bettina Koelle
,
Herbert Misiani
,
Brenda Mwalukanga
,
Douglas J. Parker
,
Rachel A. Stratton
,
Christopher M. Taylor
,
Simon O. Tucker
,
Caroline M. Wainwright
,
Richard Washington
, and
Martin R. Willet

Abstract

Pan-Africa convection-permitting regional climate model simulations have been performed to study the impact of high resolution and the explicit representation of atmospheric moist convection on the present and future climate of Africa. These unique simulations have allowed European and African climate scientists to understand the critical role that the representation of convection plays in the ability of a contemporary climate model to capture climate and climate change, including many impact-relevant aspects such as rainfall variability and extremes. There are significant improvements in not only the small-scale characteristics of rainfall such as its intensity and diurnal cycle, but also in the large-scale circulation. Similarly, effects of explicit convection affect not only projected changes in rainfall extremes, dry spells, and high winds, but also continental-scale circulation and regional rainfall accumulations. The physics underlying such differences are in many cases expected to be relevant to all models that use parameterized convection. In some cases physical understanding of small-scale change means that we can provide regional decision-makers with new scales of information across a range of sectors. We demonstrate the potential value of these simulations both as scientific tools to increase climate process understanding and, when used with other models, for direct user applications. We describe how these ground-breaking simulations have been achieved under the U.K. Government’s Future Climate for Africa Programme. We anticipate a growing number of such simulations, which we advocate should become a routine component of climate projection, and encourage international coordination of such computationally and human-resource expensive simulations as effectively as possible.

Full access
David A. Peterson
,
Laura H. Thapa
,
Pablo E. Saide
,
Amber J. Soja
,
Emily M. Gargulinski
,
Edward J. Hyer
,
Bernadett Weinzierl
,
Maximilian Dollner
,
Manuel Schöberl
,
Philippe P. Papin
,
Shobha Kondragunta
,
Christopher P. Camacho
,
Charles Ichoku
,
Richard H. Moore
,
Johnathan W. Hair
,
James H. Crawford
,
Philip E. Dennison
,
Olga V. Kalashnikova
,
Christel E. Bennese
,
Thaopaul P. Bui
,
Joshua P. DiGangi
,
Glenn S. Diskin
,
Marta A. Fenn
,
Hannah S. Halliday
,
Jose Jimenez
,
John B. Nowak
,
Claire Robinson
,
Kevin Sanchez
,
Taylor J. Shingler
,
Lee Thornhill
,
Elizabeth B. Wiggins
,
Edward Winstead
, and
Chuanyu Xu

Abstract

The 2019 Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) field experiment obtained a diverse set of in situ and remotely sensed measurements before and during a pyrocumulonimbus (pyroCb) event over the Williams Flats fire in Washington State. This unique dataset confirms that pyroCb activity is an efficient vertical smoke transport pathway into the upper troposphere and lower stratosphere (UTLS). The magnitude of smoke plumes observed in the UTLS has increased significantly in recent years, following unprecedented wildfire and pyroCb activity observed worldwide. The FIREX-AQ pyroCb dataset is therefore extremely relevant to a broad community, providing the first measurements of fresh smoke exhaust in the upper troposphere, including from within active pyroCb cloud tops. High-resolution remote sensing reveals that three plume cores linked to localized fire fronts, burning primarily in dense forest fuels, contributed to four total pyroCb “pulses.” Rapid changes in fire geometry and spatial extent dramatically influenced the magnitude, behavior, and duration of pyroCb activity. Cloud probe measurements and weather radar identify the presence of large ice particles within the pyroCb and hydrometers below cloud base, indicating precipitation development. The resulting feedbacks suggest that vertical smoke transport efficiency was reduced slightly when compared with intense pyroCb events reaching the lower stratosphere. Physical and optical aerosol property measurements in pyroCb exhaust are compared with previous assumptions. A large suite of aerosol and gas-phase chemistry measurements sets a foundation for future studies aimed at understanding the composition of smoke plumes lifted by pyroconvection into the UTLS and their role in the climate system.

Full access
J.K. Fletcher
,
C.A. Diop
,
E. Adefisan
,
M. Ahiataku
,
S.O. Ansah
,
C.E. Birch
,
H.L. Burns
,
S.J. Clarke
,
J. Gacheru
,
T.D. James
,
C.K. Ngetich Tuikong
,
D. Koros
,
V.S. Indasi
,
B.L. Lamptey
,
K.A. Lawal
,
D.J. Parker
,
A.J. Roberts
,
T.H.M. Stein
,
E. Visman
,
J. Warner
,
B.J. Woodhams
,
L.H. Youds
,
V.O. Ajayi
,
E.N. Bosire
,
C. Cafaro
,
C.A.T. Camara
,
B. Chanzu
,
C. Dione
,
W. Gitau
,
D. Groves
,
J. Groves
,
P.G. Hill
,
I. Ishiyaku
,
C.M. Klein
,
J.H. Marsham
,
B.K. Mutai
,
P.N. Ndiaye
,
M. Osei
,
T.I. Popoola
,
J. Talib
,
C.M. Taylor
, and
D. Walker

Abstract

Testbeds have become integral to advancing the transfer of knowledge and capabilities from research to operational weather forecasting in many parts of the world. The first high-impact weather testbed in tropical Africa was recently carried out through the African SWIFT program, with participation from researchers and forecasters from Senegal, Ghana, Nigeria, Kenya, the United Kingdom, and international and pan-African organizations.

The testbed aims were to trial new forecasting and nowcasting products with operational forecasters, to inform future research, and to act as a template for future testbeds in the tropics. The African SWIFT testbed integrated users and researchers throughout the process to facilitate development of impact-based forecasting methods and new research ideas driven both by operations and user input.

The new products are primarily satellite-based nowcasting systems and ensemble forecasts at global and regional convection-permitting scales. Neither of these was used operationally in the participating African countries prior to the testbed. The testbed received constructive, positive feedback via intense user interaction including fishery, agriculture, aviation, and electricity sectors.

After the testbed, a final set of recommended standard operating procedures for satellite-based nowcasting in tropical Africa have been produced. The testbed brought the attention of funding agencies and organizational directors to the immediate benefit of improved forecasts. Delivering the testbed strengthened the partnership between each country’s participating university and weather forecasting agency and internationally, which is key to ensuring the longevity of the testbed outcomes.

Full access
Ian M. Brooks
,
Margaret J. Yelland
,
Robert C. Upstill-Goddard
,
Philip D. Nightingale
,
Steve Archer
,
Eric d'Asaro
,
Rachael Beale
,
Cory Beatty
,
Byron Blomquist
,
A. Anthony Bloom
,
Barbara J. Brooks
,
John Cluderay
,
David Coles
,
John Dacey
,
Michael DeGrandpre
,
Jo Dixon
,
William M. Drennan
,
Joseph Gabriele
,
Laura Goldson
,
Nick Hardman-Mountford
,
Martin K. Hill
,
Matt Horn
,
Ping-Chang Hsueh
,
Barry Huebert
,
Gerrit de Leeuw
,
Timothy G. Leighton
,
Malcolm Liddicoat
,
Justin J. N. Lingard
,
Craig McNeil
,
James B. McQuaid
,
Ben I. Moat
,
Gerald Moore
,
Craig Neill
,
Sarah J. Norris
,
Simon O'Doherty
,
Robin W. Pascal
,
John Prytherch
,
Mike Rebozo
,
Erik Sahlee
,
Matt Salter
,
Ute Schuster
,
Ingunn Skjelvan
,
Hans Slagter
,
Michael H. Smith
,
Paul D. Smith
,
Meric Srokosz
,
John A. Stephens
,
Peter K. Taylor
,
Maciej Telszewski
,
Roisin Walsh
,
Brian Ward
,
David K. Woolf
,
Dickon Young
, and
Henk Zemmelink

As part of the U.K. contribution to the international Surface Ocean-Lower Atmosphere Study, a series of three related projects—DOGEE, SEASAW, and HiWASE—undertook experimental studies of the processes controlling the physical exchange of gases and sea spray aerosol at the sea surface. The studies share a common goal: to reduce the high degree of uncertainty in current parameterization schemes. The wide variety of measurements made during the studies, which incorporated tracer and surfactant release experiments, included direct eddy correlation fluxes, detailed wave spectra, wind history, photographic retrievals of whitecap fraction, aerosolsize spectra and composition, surfactant concentration, and bubble populations in the ocean mixed layer. Measurements were made during three cruises in the northeast Atlantic on the RRS Discovery during 2006 and 2007; a fourth campaign has been making continuous measurements on the Norwegian weather ship Polarfront since September 2006. This paper provides an overview of the three projects and some of the highlights of the measurement campaigns.

Full access
Ian M. Brooks
,
Margaret J. Yelland
,
Robert C. Upstill-Goddard
,
Philip D. Nightingale
,
Steve Archer
,
Eric d'Asaro
,
Rachael Beale
,
Cory Beatty
,
Byron Blomquist
,
A. Anthony Bloom
,
Barbara J. Brooks
,
John Cluderay
,
David Coles
,
John Dacey
,
Michael Degrandpre
,
Jo Dixon
,
William M. Drennan
,
Joseph Gabriele
,
Laura Goldson
,
Nick Hardman-Mountford
,
Martin K. Hill
,
Matt Horn
,
Ping-Chang Hsueh
,
Barry Huebert
,
Gerrit De Leeuw
,
Timothy G. Leighton
,
Malcolm Liddicoat
,
Justin J. N. Lingard
,
Craig Mcneil
,
James B. Mcquaid
,
Ben I. Moat
,
Gerald Moore
,
Craig Neill
,
Sarah J. Norris
,
Simon O'Doherty
,
Robin W. Pascal
,
John Prytherch
,
Mike Rebozo
,
Erik Sahlee
,
Matt Salter
,
Ute Schuster
,
Ingunn Skjelvan
,
Hans Slagter
,
Michael H. Smith
,
Paul D. Smith
,
Meric Srokosz
,
John A. Stephens
,
Peter K. Taylor
,
Maciej Telszewski
,
Roisin Walsh
,
Brian Ward
,
David K. Woolf
,
Dickon Young
, and
Henk Zemmelink

Abstract

No Abstract available.

Full access