Sin ttulo de diapositiva

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High-Resolution Wide-Swath Altimetry Coastal
Signals Ted Strub and Coastal Colleagues College
of Oceanic and Atmospheric Sciences Oregon State
University Joint Meeting of Ocean Sciences and
Surface Water Hydrology In Support of Wide-Swath
Altimetry Measurements October 30-31,
2006 Washington, DC
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• Coastal Issues
• Uses of high-resolution SSH surface pressure
  gradients.
• On what scales are currents geostrophic? What
  ageostrophic processes occur?
• What are the time and space scales for changes
  in SSH, along with the magnitude of the SSH
  signals
• In the inner shelf (0-10 km from the coast
  depths less than 15-50 m)?
• Over narrow shelves (10-40 km from the coast)?
• Over wide shelves (10-200 km from the coast),
  including shelf-breaks and their associated
  fronts?
• In the Coastal Transition Zone (30-500 km from
  the coast)?

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2004, D202, Hr 22
2004, D203, Hr 06
2004, D203, Hr 10
2004, D203, Hr 18
Tidal Excursions of the Columbia River Plume 10
cm over 50-100 m August 20-22, 2004
T. Strub
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5 km
SAR Image of the Columbia River Plume August 9,
2002
J. Nash
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Gan and Allen, 2002b, CODE, uniform winds, channel
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From Gan and Allen, 2002b
CODE, uniform winds, channel
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Pt. Reyes
upwelling
relaxation
From Gan and Allen, 2002b
CODE, uniform winds, channel
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From Gan and Allen, 2002a
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Density Sections from August 10 and 11, 2004
distance offshore (km)
Equatorward
Geostrophic Velocity on August 11, 2004
Poleward
A. Kirincich/J. Barth OSU)
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15 m Mooring Data (Inner Shelf)
Section
Alongshore Wind Stress
Alongshore Velocity
8-Day Sampling
15 m Bottom Pressure (db) (SSH m)
A. Kirincich/J. Barth OSU)
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J. Barth
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45N
44.1N
J. Barth
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J. Barth
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J. Barth
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J. Barth
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J. Barth
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What do real altimeters see in the region next to
the coast? Jason-1 data on tracks 247 and 28 are
being extended closer to the coast by
substituting ECMWF water vapor for the microwave
radiometer wet tropo correction.
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Extending the Altimeter Alongtrack SSH to the
Coast 2005
June 18
June 28
July 8
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Extending the Altimeter Alongtrack SSH to the
Coast 2005
July 18
July 28
August 27
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Wet Troposphere Corrections from Jason Microwave,
NCEP ECMWF
Pass 28, Cycle 130
Pass 28, Cycle 131
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Jason-1 Pass 28, Cycle 130 July 18, 2005
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• Coastal Issues
• On what scales are currents geostrophic? What
  ageostrophic processes occur? External tides with
  large signals ( meter). Internal tides and
  currents (10s of cm over scales of less than 1
  km). Ageostrophic currents during changes in the
  wind (10s of cm/s). Geostrophic adjustment takes
  1-2 inertial periods.
• In the inner shelf (0-10 km from the coast
  depths less than 15-50 m), SSH signals are 5-20
  cm, with time scales of 1-5 days.
• Over narrow shelves (10-40 km from the coast),
  again, SSH scales are 10-30 cm, with longer
  periods of several days or longer.

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• Over wide shelves (10-200 km from the coast),
  including shelf-breaks, currents can be 10-50
  cm/s, with scales of 10-100 km.
• In the Coastal Transition Zone (30-500 km from
  the coast), currents of 50-100 cm/s have SSH
  changes of 20-40 cm over 10-20 km.

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