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The Inferred 3D velocity fieldNelson Hogg (WHOI)
The Inferred 3D velocity fieldNelson Hogg (WHOI)
Nelson Hogg:
Missing PN
Ranks with altimetry in terms of innovation and global reach
Nelson Hogg:
Missing PN
Ranks with altimetry in terms of innovation and global reach
ThemesThemes
• Global coverage
• Influence of bottom topography
• Zonality of mid-depth flows
• Presence of annual signal at mid-depths
• Numerical models do reproduce some of these features
Surface: Mean Meridional Velocity
Niiler and Maximenko (personal communication)
Nelson Hogg:
Change in sign of ekman @ equator
Nelson Hogg:
Change in sign of ekman @ equator
Surface: Mean Zonal Component
Niiler and Maximenko (personal communication)
Nelson Hogg:
Banding in tropics
wbcs
Nelson Hogg:
Banding in tropics
wbcs
Surface: Eddy Kinetic Energy
Niiler and Maximenko (personal communication) Stammer (persnonal communication)
SatelliteSurface Drifters
Kuroshio Extension:RMS eddy
velocities from drifters and
altimeters, and their ratio
Niiler et al, 2002: (in press)
Drifter RMS
Altimeter RMS
Drifter / Altimeter
CoriolisPressure
Centrifugal
CoriolisPressure
Centrifugal
Niiler et al, 2002: (in press)
Shatsky Rise
Emperor Seamounts
Izu Ridge
Mean Surface Velocity: Kuroshio Extension
North Atlantic: Mean Surface Circulation
Fratantoni, 2001, JGR 106(10)
Nelson Hogg:
New england seamounts
recirculations
NAC and CGFZ
Nelson Hogg:
New england seamounts
recirculations
NAC and CGFZ
EKE Difference: Drifter – Altimeter
Fratantoni, 2001, JGR 106(10)
North Atlantic: Mean surface velocity
Niiler and Maximenko, pers. comm.
Nelson Hogg:
New England Seamounts
Azores C
NAC & CGFZ
Reykianes Ridge
Lab Sea and offshore recirc
Nelson Hogg:
New England Seamounts
Azores C
NAC & CGFZ
Reykianes Ridge
Lab Sea and offshore recirc
“Upper level” Streamlines
Bower et al, 2002: Nature
Lavender et al, 2000: Nature
700m
Nelson Hogg:
See posters
Nelson Hogg:
See posters
LSW Streamlines
Bower et al, 2002: Nature
1500m – 1750m
Nelson Hogg:
CGFZ
Split at eastern b.
Reyk. Ridge
Nelson Hogg:
CGFZ
Split at eastern b.
Reyk. Ridge
Influence of Mid-Atlantic Ridge on Rafos trajectories
Bower et al, 2002, Nature
AAIW: South Atlantic
Boebel et al, 1999, GRL 26
Nelson Hogg:
Color scheme
Eastward @ 20S
Nelson Hogg:
Color scheme
Eastward @ 20S
IW (1000m) trajectories: North Pacific
Steve Riser, pers. Comm.
Nelson Hogg:
Zonal trajectories
Rounder streamlines
Nelson Hogg:
Zonal trajectories
Rounder streamlines
AAIW displacements: South Pacific
Davis, 1998, JGR 103
AAIW smoothed: South Pacific
Davis, 1998, JGR 103
AAIW streamlines: South Pacific
Davis, 1998, JGR 103
NADW: Brazil Basin (DBE)
RAFOS Displacements CLIPPER simulation
Hogg and Owens, 1999: DSRII Treguier et al, 2002: JPO
Treguier et al, 2002: JPO
Vanicek and Siedler, 2002:JPO
MAR influence?
Possible Explanations●Fracture Zones: Pedlosky (JPO,31)
●Variable mixing along MAR●Wind forced: Nakano and Suginohara (JPO, 32)
Wind forced mid-depth zonal flows
South AtlanticClipper 1/6 degreeTreguier et al, 2002: JPO
PacificCOCO 1 degreeNakano and Suginahara, 2002: JPO
Nelson Hogg:
See posters
Nelson Hogg:
See posters
Annual signal in South Pacific
Davis, 1998: JGR
Annual signal in Brazil Basin: Least squares fit @ 2500m
RMS residual U V
Hogg, in prep.
U
V
Annual signal in Brazil Basin:Phase
Hogg, in prep.
Annual signal in Brazil Basin:Amplitude
Hogg, in prep.
Annual Signal from Clipper:Zonal Velocity
Thierry and Teguier, pers. Comm.
Amplitude (cm/s) Phase (months)
Beta dispersion
Hogg, in prep.
Application to inverse calculations
Pacifiic: 32S
Wijffels et al, 2001: JPO
Total: 1784 floats, 4300 float years
Nelson Hogg:
3650 = 1 float continuous for 10 yr
Nelson Hogg:
3650 = 1 float continuous for 10 yr
Summary
● Float/drifter program has been a remarkable success and should be considered one of WOCE's
crown jewels● Much of the information is only semi-quantitative
at best: more drifters of longer duration needed● Use in constraining inverse models still in
infancy: should be encouraged
● Float/drifter program has been a remarkable success and should be considered one of WOCE's
crown jewels● Much of the information is only semi-quantitative
at best: more drifters of longer duration needed● Use in constraining inverse models still in
infancy: should be encouraged
Nelson Hogg:
Davis poster
Nelson Hogg:
Davis poster