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Instrument and Its Main Features
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Measured Electromagnetic Parameters
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Inferred Ocean Parameters
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Footprint
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Swath Width
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Additional Information
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Altimeter: sends short pulses at nadir incidence (13-GHz carrier frequency; TOPEX altimeter will also have a 5-GHz channel)
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Travel time of a return pulse, radar cross section, shape of a return pulse
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Sea level height
Wind speed
Significant wave height
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Circular, 5- to 12-km diameter, depending on surface roughness
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One-pixel diam. ˜10 km
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Along-track pixel spacing: ~7 km. Distance between tracks at equator: ~150 km. 10 to 20 days exact repetition of all orbits
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Scatterometer: sends short pulses in a range of incidence angles from 20 to 60 degrees, using both strictly horizontal (HH) and strictly vertical (W) polarizations; 14-GHz carrier frequency
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A set of radar cross sections for each surface bin, at several azimuthal angles and polariza-tions
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Wind speed
Wind direction
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Aspect ratio ~1:4. Major axis: 30 to 90 km depending on position within the swath, etc.
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Two swaths 600 to 700 km each
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Global coverage every 2 days
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Synthetic aperture radar: high-spatial-resolution radar images of sea surface roughness distribution for C, L, and X bands. Other bands have also been employed
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Analog and/or digital matrices of radar cross section showing spatial varia-tion of surface roughness
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Length and direction, or surface gravity and internal waves, wave number spectra of surface roughness spatial variation, surface signatures of mesoscale eddies, fronts, current boundaries, sea ice, bathymetry
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10- to 100-m linear size, depending on the mode frequency electromagnetic band, etc.
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Hundreds of kilometers
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Usually only regional coverage for selected locations
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Special Sensor Microwave/Imager (SSM/I) with channels (GHz):
19.4
22.2
37.0
85.5
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Radio brightness temperature
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Characteristics of atmosphere (e.g., water content); surface wind speed, sea ice
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Length
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Width
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1300 km
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Almost total global coverage obtained every day
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(km)
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70
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45
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60
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40
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38
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30
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16
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14
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Scanning Multichannel Microwave Radiometer (SMMR) with channels (GHz):
37.0
21.0
18.0
10.7
6.6
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Radio brightness temperature
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Characteristics of atmosphere (e.g., water content); surface wind speed, sea surface temperature, sea ice
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Length
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Width
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780 km
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Almost total global coverage every 2 days
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(km)
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|
22
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14
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|
28
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25
|
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43
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28
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74
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49
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120
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79
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SOURCE: Courtesy of Roman Glazman, Jet Propulsion Laboratory, California Institute of Technology.
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