Oceanic mesoscale processes determined from satellite altimetry and the prospects of a wide-

swath radar altimeter

Lee-Lueng Fu Jet Propulsion Laboratory

California Institute of Technology

Ocean Sciences MeetingMarch 5, 2008

Orlando, Florida

A snapshot of sea surface height anomalies from T/P and ERS altimeters

T=0

T= -7 days

T= -14 days

T= 7 days

T= 14 days

Space-time Maximum Cross-Correlation Analysis

),,(),,(,,, TtyyxxhtyxhTyxC yx

i i

iiiii i

C

TyTxCvu

/,/),(

xi ,y

i

Eddy propagation velocity (zonal)

km/day

Eddy propagation velocity (meridional)

km/day

10 km/day

Eddy Propagation velocity and SSH standard deviation: the South Atlantic

Eddy propagation velocity with bathymetry: the Gulf Stream

10 km/day

Bermuda

New England Seamount chain

Eddy propagation velocity with bathymetry: the Southern Ocean

Kerguelen Plateau

10 km/day

altimetry

ECCO-2

Eastward velocity (km/day)

Eddy zonal propagation speed

km/d

ay

altimetry

ECCO model

First mode Rossby waves

Latitude

22 )0()( CdssCL

Correlation of SSH time series as function of spatial separation

A spatial scale computed as follows:

km

L= 210 km

SSH wavenumber spectra (Ducet et al. 2000)

T/P along-track

T/P-ERS mapped

T/P mapped

Overlapping at 150 km

Spatial scales of the AVISO T/P-ERS merged data

Scales shorter than 200 km are not resolved.

210 km

90% of the ocean’s kinetic energy is contained at scales not well resolved by a nadir-looking altimeter

100 km

ground tracks of Jason (thick) and T/P (thin) Tandem Mission

100 km scale eddies 10 km scale eddies

Altimetry SSH wavenumber spectrum

Wavenumber (cycles/km)

Pow

er d

ensi

ty (

cm2 /

cycl

es/k

m)

Noise level of SWOT

Jason pass 132 (147 cycle average)

Instrument noise

Surface Water and Ocean Topography Mission (SWOT)