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R. Chen
,
D. L. Boyer
, and
L. Tao

Abstract

No abstract available

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Jacques Verron
,
Dominique Renouard
,
Gabriel Chabert D'Hieres
,
Thong Nguyen
,
Henri Didelle
, and
Don L. Boyer

Abstract

Alongshore oscillatory flows over an elongated topographic feature next to a vertical wall for a homogeneous, rotating fluid were investigated by means of numerical and laboratory experiments. The physical experiments were conducted in the Grenoble 13-m diameter rotating tank, in which an elongated obstacle of limited longitudinal extent was placed along the vertical sidewall. The background oscillating motion was obtained by periodically varying the platform angular velocity. Fluid motions were visualized and quantified by direct velocity measurements and particle tracking. The numerical model employed was a tridimensional model developed by Haidvogel et al. It consists of the traditional primitive equations, that is, the Navier-Stokes equations for a rotating fluid with the addition of the hydrostatic, Boussinesq, and incompressibility approximations. (The experiments described here employ the homogeneous version.) The numerical formulation uses finite differences in the horizontal and spectral representation in the vertical dimensions.

Both the laboratory and numerical experiments show that in the range of dimensionless parameters considered, two distinct flow regimes, based on general properties of the rectified flow patterns observed, can be defined. It is further shown that the flow regime designation depends principally on the magnitude of the temporal Rossby number, Ro t , defined as the ratio of the flow oscillation to the background rotation frequency. Good qualitative and quantitative agreement is found between the laboratory experiments and the numerical model for such observables as the spatial distribution of rectified flow patterns. Several other flow observables are defined and their relation with the system parameters delineated.

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Don L. Boyer
,
Gabriel Chabert d'Hieres
,
Henri Didelle
,
Jacques Verron
,
Rui-Rong Chen
, and
Lijun Tao

Abstract

The problem of the oscillatory motion of a homogeneous, rotating fluid in the vicinity of an isolated topographic feature is investigated in the laboratory and numerically. The laboratory experiments are conducted by fixing a cosine-squared body of revolution near the outer boundary of a circular tank rotating about a vertical axis with an angular velocity Ω(t)=Ω0+Ω1sinωt, where Ω0 is the mean background rotation and Ω0 and ω are the magnitude and frequency of an oscillatory component. Experiments with an oscillatory flow show clearly that a mean anticyclonic vortex is formed in the vicinity of the topographic feature. Surface floats are used to determine typical particle paths for various flow conditions and these are shown to vary markedly with the Rossby and temporal Rossby numbers of the background flow. Eulerian velocity profiles along and normal to the streamwise axis are used to quantify the anticyclonic vortex. A scaling analysis is advanced to show how the strength and distribution of the anticyclonic current varies with the various system parameters. The laboratory findings are in good agreement with the scaling analysis and with the theoretical model of Wright and Loder.

A nonlinear numerical model, using the quasi-geostrophic potential vorticity equation, is considered; the results correlate well with the scaling analysis and the laboratory experiments. The laboratory and numerical experiments are used to estimate the magnitude of the mean anticyclonic motion that might be expected in the vicinity of Fieberling Guyot. Future laboratory and numerical experiments will consider the additional feature of background stratification.

Full access
J. Vialard
,
J. P. Duvel
,
M. J. McPhaden
,
P. Bouruet-Aubertot
,
B. Ward
,
E. Key
,
D. Bourras
,
R. Weller
,
P. Minnett
,
A. Weill
,
C. Cassou
,
L. Eymard
,
T. Fristedt
,
C. Basdevant
,
Y. Dandonneau
,
O. Duteil
,
T. Izumo
,
C. de Boyer Montégut
,
S. Masson
,
F. Marsac
,
C. Menkes
, and
S. Kennan

The Vasco-Cirene program explores how strong air-sea interactions promoted by the shallow thermocline and high sea surface temperature in the Seychelles-Chagos thermocline ridge results in marked variability at synoptic, intraseasonal, and interannual time scales. The Cirene oceanographic cruise collected oceanic, atmospheric, and air-sea flux observations in this region in January–February 2007. The contemporaneous Vasco field experiment complemented these measurements with balloon deployments from the Seychelles. Cirene also contributed to the development of the Indian Ocean observing system via deployment of a mooring and 12 Argo profilers.

Unusual conditions prevailed in the Indian Ocean during January and February 2007, following the Indian Ocean dipole climate anomaly of late 2006. Cirene measurements show that the Seychelles-Chagos thermocline ridge had higher-than-usual heat content with subsurface anomalies up to 7°C. The ocean surface was warmer and fresher than average, and unusual eastward currents prevailed down to 800 m. These anomalous conditions had a major impact on tuna fishing in early 2007. Our dataset also sampled the genesis and maturation of Tropical Cyclone Dora, including high surface temperatures and a strong diurnal cycle before the cyclone, followed by a 1.5°C cooling over 10 days. Balloonborne instruments sampled the surface and boundary layer dynamics of Dora. We observed small-scale structures like dry-air layers in the atmosphere and diurnal warm layers in the near-surface ocean. The Cirene data will quantify the impact of these finescale features on the upper-ocean heat budget and atmospheric deep convection.

Full access
J. Vialard
,
J. P. Duvel
,
M. J. Mcphaden
,
P. Bouruet-Aubertot
,
B. Ward
,
E. Key
,
D. Bourras
,
R. Weller
,
P. Minnett
,
A. Weill
,
C. Cassou
,
L. Eymard
,
T. Fristedt
,
C. Basdevant
,
Y. Dandonneau
,
O. Duteil
,
T. Izumo
,
C. de Boyer Montégut
,
S. Masson
,
F. Marsac
,
C. Menkes
, and
S. Kennan

Abstract

The Vasco—Cirene field experiment, in January—February 2007, targeted the Seychelles—Chagos thermocline ridge (SCTR) region, with the main purpose of investigating Madden—Julian Oscillation (MJO)-related SST events. The Validation of the Aeroclipper System under Convective Occurrences (Vasco) experiment (Duvel et al. 2009) and Cirene cruise were designed to provide complementary views of air—sea interaction in the SCTR region. While meteorological balloons were deployed from the Seychelles as a part of Vasco, the Research Vessel (R/V) Suroît was cruising the SCTR region as a part of Cirene.

Full access
G. C Johnson
,
R Lumpkin
,
C Atkinson
,
Tiago Biló
,
Tim Boyer
,
Francis Bringas
,
Brendan R. Carter
,
Ivona Cetinić
,
Don P. Chambers
,
Duo Chan
,
Lijing Cheng
,
Leah Chomiak
,
Meghan F. Cronin
,
Shenfu Dong
,
Richard A. Feely
,
Bryan A. Franz
,
Meng Gao
,
Jay Garg
,
John Gilson
,
Gustavo Goni
,
Benjamin D. Hamlington
,
W. Hobbs
,
Zeng-Zhen Hu
,
Boyin Huang
,
Masayoshi Ishii
,
Svetlana Jevrejeva
,
W. Johns
,
Peter Landschützer
,
Matthias Lankhorst
,
Eric Leuliette
,
Ricardo Locarnini
,
John M. Lyman
,
Michael J. McPhaden
,
Mark A. Merrifield
,
Alexey Mishonov
,
Gary T. Mitchum
,
Ben I. Moat
,
Ivan Mrekaj
,
R. Steven Nerem
,
Sarah G. Purkey
,
Bo Qiu
,
James Reagan
,
Katsunari Sato
,
Claudia Schmid
,
Jonathan D. Sharp
,
David A. Siegel
,
David A. Smeed
,
Paul W. Stackhouse Jr.
,
William Sweet
,
Philip R. Thompson
,
Joaquin A. Triñanes
,
Denis L. Volkov
,
Rik Wanninkhof
,
Caihong Wen
,
Toby K. Westberry
,
Matthew J. Widlansky
,
J. Willis
,
Ping-Ping Xie
,
Xungang Yin
,
Huai-min Zhang
,
Li Zhang
,
Jessicca Allen
,
Amy V. Camper
,
Bridgette O. Haley
,
Gregory Hammer
,
S. Elizabeth Love-Brotak
,
Laura Ohlmann
,
Lukas Noguchi
,
Deborah B. Riddle
, and
Sara W. Veasey
Open access
Gregory C. Johnson
,
Rick Lumpkin
,
Simone R. Alin
,
Dillon J. Amaya
,
Molly O. Baringer
,
Tim Boyer
,
Peter Brandt
,
Brendan R. Carter
,
Ivona Cetinić
,
Don P. Chambers
,
Lijing Cheng
,
Andrew U. Collins
,
Cathy Cosca
,
Ricardo Domingues
,
Shenfu Dong
,
Richard A. Feely
,
Eleanor Frajka-Williams
,
Bryan A. Franz
,
John Gilson
,
Gustavo Goni
,
Benjamin D. Hamlington
,
Josefine Herrford
,
Zeng-Zhen Hu
,
Boyin Huang
,
Masayoshi Ishii
,
Svetlana Jevrejeva
,
John J. Kennedy
,
Marion Kersalé
,
Rachel E. Killick
,
Peter Landschützer
,
Matthias Lankhorst
,
Eric Leuliette
,
Ricardo Locarnini
,
John M. Lyman
,
John J. Marra
,
Christopher S. Meinen
,
Mark A. Merrifield
,
Gary T. Mitchum
,
Ben I. Moat
,
R. Steven Nerem
,
Renellys C. Perez
,
Sarah G. Purkey
,
James Reagan
,
Alejandra Sanchez-Franks
,
Hillary A. Scannell
,
Claudia Schmid
,
Joel P. Scott
,
David A. Siegel
,
David A. Smeed
,
Paul W. Stackhouse
,
William Sweet
,
Philip R. Thompson
,
Joaquin A. Triñanes
,
Denis L. Volkov
,
Rik Wanninkhof
,
Robert A. Weller
,
Caihong Wen
,
Toby K. Westberry
,
Matthew J. Widlansky
,
Anne C. Wilber
,
Lisan Yu
, and
Huai-Min Zhang
Free access
Gregory C. Johnson
,
Rick Lumpkin
,
Tim Boyer
,
Francis Bringas
,
Ivona Cetinić
,
Don P. Chambers
,
Lijing Cheng
,
Shenfu Dong
,
Richard A. Feely
,
Baylor Fox-Kemper
,
Eleanor Frajka-Williams
,
Bryan A. Franz
,
Yao Fu
,
Meng Gao
,
Jay Garg
,
John Gilson
,
Gustavo Goni
,
Benjamin D. Hamlington
,
Helene T. Hewitt
,
William R. Hobbs
,
Zeng-Zhen Hu
,
Boyin Huang
,
Svetlana Jevrejeva
,
William E. Johns
,
Sato Katsunari
,
John J. Kennedy
,
Marion Kersalé
,
Rachel E. Killick
,
Eric Leuliette
,
Ricardo Locarnini
,
M. Susan Lozier
,
John M. Lyman
,
Mark A. Merrifield
,
Alexey Mishonov
,
Gary T. Mitchum
,
Ben I. Moat
,
R. Steven Nerem
,
Dirk Notz
,
Renellys C. Perez
,
Sarah G. Purkey
,
Darren Rayner
,
James Reagan
,
Claudia Schmid
,
David A. Siegel
,
David A. Smeed
,
Paul W. Stackhouse
,
William Sweet
,
Philip R. Thompson
,
Denis L. Volkov
,
Rik Wanninkhof
,
Robert A. Weller
,
Caihong Wen
,
Toby K. Westberry
,
Matthew J. Widlansky
,
Josh K. Willis
,
Lisan Yu
, and
Huai-Min Zhang
Free access
G. C. Johnson
,
R. Lumpkin
,
Michael A. Alexander
,
Dillon J. Amaya
,
Brian Beckley
,
Tim Boyer
,
Francis Bringas
,
Brendan R. Carter
,
Ivona Cetinić
,
Don P. Chambers
,
Duo Chan
,
Lijing Cheng
,
Shenfu Dong
,
Shane Elipot
,
Richard A. Feely
,
Bryan A. Franz
,
Yao Fu
,
Meng Gao
,
Jay Garg
,
Donata Giglio
,
John Gilson
,
Marlos Goes
,
Garrett Graham
,
Benjamin D. Hamlington
,
Will Hobbs
,
Zeng-Zhen Hu
,
Boyin Huang
,
Masayoshi Ishii
,
Michael G. Jacox
,
Annika Jersild
,
Svetlana Jevrejeva
,
William E. Johns
,
Rachel. E. Killick
,
Mikael Kuusela
,
Peter Landschützer
,
Eric Leuliette
,
Chao Liu
,
Ricardo Locarnini
,
Susan M. Lozier
,
John M. Lyman
,
Mark A. Merrifield
,
Alexey Mishonov
,
Gary T. Mitchum
,
Ben I. Moat
,
R. Steven Nerem
,
Mitsuho Oe
,
Renellys C. Perez
,
Ivenis Pita
,
Sarah G. Purkey
,
James Reagan
,
Kanako Sato
,
Claudia Schmid
,
David A. Smeed
,
Ryan H. Smith
,
Paul W. Stackhouse Jr.
,
Thea Sukianto
,
William Sweet
,
Philip R. Thompson
,
Joaquin A. Triñanes
,
Denis L. Volkov
,
Rik Wanninkhof
,
Robert A. Weller
,
Toby K. Westberry
,
Matthew J. Widlansky
,
Josh K. Willis
,
Xungang Yin
,
Lisan Yu
, and
Huai-min Zhang
Open access
Molly Baringer
,
Mariana B. Bif
,
Tim Boyer
,
Seth M. Bushinsky
,
Brendan R. Carter
,
Ivona Cetinić
,
Don P. Chambers
,
Lijing Cheng
,
Sanai Chiba
,
Minhan Dai
,
Catia M. Domingues
,
Shenfu Dong
,
Andrea J. Fassbender
,
Richard A. Feely
,
Eleanor Frajka-Williams
,
Bryan A. Franz
,
John Gilson
,
Gustavo Goni
,
Benjamin D. Hamlington
,
Zeng-Zhen Hu
,
Boyin Huang
,
Masayoshi Ishii
,
Svetlana Jevrejeva
,
William E. Johns
,
Gregory C. Johnson
,
Kenneth S. Johnson
,
John Kennedy
,
Marion Kersalé
,
Rachel E. Killick
,
Peter Landschützer
,
Matthias Lankhorst
,
Tong Lee
,
Eric Leuliette
,
Feili Li
,
Eric Lindstrom
,
Ricardo Locarnini
,
Susan Lozier
,
John M. Lyman
,
John J. Marra
,
Christopher S. Meinen
,
Mark A. Merrifield
,
Gary T. Mitchum
,
Ben Moat
,
Didier Monselesan
,
R. Steven Nerem
,
Renellys C. Perez
,
Sarah G. Purkey
,
Darren Rayner
,
James Reagan
,
Nicholas Rome
,
Alejandra Sanchez-Franks
,
Claudia Schmid
,
Joel P. Scott
,
Uwe Send
,
David A. Siegel
,
David A. Smeed
,
Sabrina Speich
,
Paul W. Stackhouse Jr.
,
William Sweet
,
Yuichiro Takeshita
,
Philip R. Thompson
,
Joaquin A. Triñanes
,
Martin Visbeck
,
Denis L. Volkov
,
Rik Wanninkhof
,
Robert A. Weller
,
Toby K. Westberry
,
Matthew J. Widlansky
,
Susan E. Wijffels
,
Anne C. Wilber
,
Lisan Yu
,
Weidong Yu
, and
Huai-Min Zhang
Free access