Ocean colour, sea surface temperature and sea surface height

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Ocean colour, sea surface temperature and sea
surface height

• Jim Gower
• IOS, Sidney BC, Canada
• gowerj_at_pac.dfo-mpo.gc.ca
• Marine Remote Sensing Workshop, Oct 27 2004
• Dunsmuir Lodge, Sidney, BC

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Satellite Data at IOS

• Images received locally are from AVHRR (thermal,
  visible SST and bright blooms) and SeaWiFS
  (water colour phytoplankton productivity and
  blooms)
• Images received regularly via web and CD are
  MODIS and MERIS (water colour), and Radarsat 1.
• Other image data, Landsat (Visible patterns,
  sediment, blooms, high resolution, 15m, 30m).
  Expensive and infrequent coverage. Other options
  are Ikonos (1, 4m resolution), ASTER 90m thermal
• Non image data Altimetry (Sea surface height
  eddy mapping, currents).
• Other non image data scatterometer winds (for
  driving ocean models).

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Ocean Colour

• Earliest data from CZCS 1978 to 1986, 4 water
  colour bands, 8 bits, 1 km resolution
• Longest data series from AVHRR weather satellite
  1980 to present, 2 general use bands, 10 bits, 1
  km resolution.
• First modern data from SeaWiFS, 1997 to end of
  2004, 8 water colour bands, 8 bits, 1 km
  resolution.
• New data from NASAs MODIS (one on each of Aqua
  and Terra satellites), 9 water colour bands, and
  many others including thermal IR, 12 bits, 1 km
  resolution (to 250 m on land).
• New data from ESAs MERIS, May 2002 onwards, 12
  water colour bands, 14 bits. No thermal IR, 300
  m resolution (most data at 1.2km)

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True (2,5,7)
Algal 1MERIS FR data 28 June 2003
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FLH (7,8,9) MCI
(8,9,10)MERIS FR data 28 June 2003
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Above-surface reflectance spectra observed off
Vancouver Island with the IOS spectrometer. 1
and 16 mg.m-3 chlorophyll. MERIS bands 1 to 12
plotted
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Water reflectance model based on Morel et al.,
(1988), with fluorescence at 685 nm
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One swath of Seawifs
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Using the computer to tilt and zoom the satellite
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SERIES (Subarctic Ecosystem Response to Iron
Enrichment Study) 29 July 2002
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SERIES (Subarctic Ecosystem Response to Iron
Enrichment Study) 29 July 2002(Mid-ocean
aquaculture?)
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NOAA 14 weather satellite, 21 Oct 1996
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Sea surface temperature

• Earliest and longest data series from AVHRR
  weather satellite 1980 to present, 3 thermal
  bands (split window plus mid-IR), 10 bits, SST to
  better than 1K, 1 km resolution.
• Improved data from ATSR, AATSR with oblique and
  standard viewing 1991 to present, aiming for
  0.3K, 1 km resolution
• New data from NASAs MODIS (one on each of Aqua
  and Terra satellites), SST to 0.3 to 0.5K, 1 km
  resolution
• New data from NASA/Japan ASTER, 90 m resolution,
  less absolute accuracy

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Sea Surface Temperature image composite 1-10
March 1995 without north-south trend
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NWT hot spots, summer 1994
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NWT smoke, summer 1994
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Microwave sensors

• Imaging Radar Seasat SAR 1978, ERS SAR 1991 to
  present, Radarsat 1996 to present, Envisat ASAR.
• Altimeter Skylab, Geos 3, Seasat, Geosat, ERS,
  Topex/Poseidon, Jason, Envisat, with improving
  accuracy from 1 m down to 2 cm.
• Scatterometer Seasat, ERS, Seawinds, wind speed
  to 15 degrees, 2 m/s
• Microwave radiometer Seasat, Nimbus 7, SSMI,
  AMSR. Sea surface temperature (50 km resolution)
  and ice extent (10 km resolution) through cloud
• Future microwave radiometer for sea surface
  salinity. 0.1 psu, with low spatial resolution
  (100 km)

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IMAGING RADAR

• Sharp images through cloud and at night using
  large synthetic aperture, but not seeing colour
  or temperature

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Wind patterns off B.C. coast, Radarsat ScanSAR
12 April 1997
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Wind patterns in winter storm off Labrador,
Radarsat ScanSAR 13 January 1999
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Prestige oil spill 17 Nov 2002 off Spain
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Prestige oil spill Nov 2002 off Spain
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Prestige oil spill Nov 2002 off Spain
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Radarsat ScanSAR 25 August 1997, 0730 PDT
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BC Seine fishing fleet 30 minutes after the start
of a 36 hour opening in the mouth of Juan de Fuca
Strait.25 August 1997
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Radarsat ScanSAR image, 8 August 1997, 1920 PDT
at a time of a bright plankton bloom in Hecate
Strait. Measured surface wind speed was less
than 2 m/s at the two buoys in the Strait, higher
(7.5 m/s) in Dixon Entrance.
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RADAR ALTIMETER

• Sea surface height to centimeters (in spite of
  waves, weather and tides) giving detailed water
  current maps

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RADAR SCATTEROMETER

• Wind speed and direction by measuring roughness
  from different angles

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Conclusions

• IOS has access to an increasing variety of
  satellite images and other data.
• Large collections of visible and thermal imagery
  are made available on the web http//www-sci.pac.d
  fo-mpo.gc.ca/osap/data/SearchTools/
  SearchSatellites_e.asp
• NASA makes large collections of data available on
  their Satellite Active Archive (SAA)
  http//www.saa.noaa.gov/nsaa/products/welcome and
  via Distributed Active Archive Centers.
  http//daac.gsfc.nasa.gov/data/
• Watch for new satellite products bloom
  detection, salinity, surface currents?

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• END
• FIN
• Jim Gower
• gowerj_at_pac.dfo-mpo.gc.ca