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