Imaging Microwave Radiometers in Space

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Imaging Microwave Radiometers in Space

• Per Gloersen
• Oceans and Ice Branch (971)

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The Nimbus Microwave Imager Heritage
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The Nimbus Microwave Imager Heritage

• December 1972 Nimbus 5 launched with the
  Electrically Scanned Microwave Radiometer (ESMR)
  on board.

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The Nimbus Microwave Imager Heritage

• December 1972 Nimbus 5 launched with the
  Electrically Scanned Microwave Radiometer (ESMR)
  on board.- The first successful microwave imager
  in space.

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The Nimbus Microwave Imager Heritage

• December 1972 Nimbus 5 launched with the
  Electrically Scanned Microwave Radiometer (ESMR)
  on board.- The first successful microwave imager
  in space.- Original motive Mapping global
  rainfall rates.

6
The Nimbus Microwave Imager Heritage

• December 1972 Nimbus 5 launched with the
  Electrically Scanned Microwave Radiometer (ESMR)
  on board.- The first successful microwave imager
  in space.- Original motive Mapping global
  rainfall rates.- Prime motive evolving after
  launch Mapping global sea ice coverage.

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The Nimbus Microwave Imager Heritage

• December 1972 Nimbus 5 launched with the
  Electrically Scanned Microwave Radiometer (ESMR)
  on board.- The first successful microwave imager
  in space.- Original motive Mapping global
  rainfall rates.- Prime motive evolving after
  launch Mapping global sea ice coverage.
• October 1978 Nimbus 7 launched with the
  Scanning Multichannel Microwave Radiometer (SMMR)
  on board.

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The Nimbus Microwave Imager Heritage

• December 1972 Nimbus 5 launched with the
  Electrically Scanned Microwave Radiometer (ESMR)
  on board.- The first successful microwave imager
  in space.- Original motive Mapping global
  rainfall rates.- Prime motive evolving after
  launch Mapping global sea ice coverage.
• October 1978 Nimbus 7 launched with the
  Scanning Multichannel Microwave Radiometer (SMMR)
  on board.- Multiple channels permitted
  distinguishing between first-year and multiyear
  sea ice types.

9
The Nimbus Microwave Imager Heritage

• December 1972 Nimbus 5 launched with the
  Electrically Scanned Microwave Radiometer (ESMR)
  on board.- The first successful microwave imager
  in space.- Original motive Mapping global
  rainfall rates.- Prime motive evolving after
  launch Mapping global sea ice coverage.
• October 1978 Nimbus 7 launched with the
  Scanning Multichannel Microwave Radiometer (SMMR)
  on board.- Multiple channels permitted
  distinguishing between first-year and multiyear
  sea ice types.- Nearly nine-year lifetime
  allowed SMMR to be a major contributor to the
  present 32-year sea ice record.

10
The Nimbus Microwave Imager Heritage

• December 1972 Nimbus 5 launched with the
  Electrically Scanned Microwave Radiometer (ESMR)
  on board.- The first successful microwave imager
  in space.- Original motive Mapping global
  rainfall rates.- Prime motive evolving after
  launch Mapping global sea ice coverage.
• October 1978 Nimbus 7 launched with the
  Scanning Multichannel Microwave Radiometer (SMMR)
  on board.- Multiple channels permitted
  distinguishing between first-year and multiyear
  sea ice types.- Nearly nine-year lifetime
  allowed SMMR to be a major contributor to the
  present 32-year sea ice record.- Multiple
  channels also permitted observation of global sea
  surface temperatures independent of cloud
  cover.

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The Nimbus 5 ESMR

• 103 antenna sticks with independent phase
  shifters
• Phase shifters driven withphase differences to
  achievecross-track scanning at nadir,with no
  moving parts.
• Single-channel, horizontally-polarized operation
  at a wave-length of 1.55 cm.

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• This was the first and only time the Weddell
  Polynya was ever observed.

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The Nimbus 7 SMMR

• Launched in October 1978
• Turned off in August 1987

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The Nimbus 7 SMMR

• Launched in October 1978
• Turned off in August 1987
• Provided 1/3 of the baseline 32-year sea ice
  extent data

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The Nimbus 7 SMMR

• Launched in October 1978
• Turned off in August 1987
• Provided 1/3 of the baseline 32-year sea ice
  extent data
• The other 2/3 provided by ESMR three DOD SSMIs

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Nimbus 7 SMMR

• Shown before launch in the anechoic test chamber
• The solar panels are not attached.
• The radiometers are in the sensory ring.
• The oscillatory reflector is located to the right
  on top of the sensory ring.
• There are 10 channels receiving vertically and
  horizontally polarized radiances at 5 different
  wavelengths 0.8, 1.4, 1.7, 2.7, and 4.6 cm
• Over 150 articles using SMMR data have been
  published in scientific journals.

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What can SMMR do with its ten channels?

• Greatly improves on ESMRs ability to obtain sea
  ice concentrations.

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What can SMMR do with its ten channels?

• Greatly improves on ESMRs ability to obtain sea
  ice concentrations.
• Permits distinguishing between first-year and
  multiyear sea ice.

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What can SMMR do with its ten channels?

• Greatly improves on ESMRs ability to obtain sea
  ice concentrations.
• Permits distinguishing between first-year and
  multiyear sea ice.
• Obtains sea surface temperatures globally through
  clouds.

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What can SMMR do with its ten channels?

• Greatly improves on ESMRs ability to obtain sea
  ice concentrations.
• Permits distinguishing between first-year and
  multiyear sea ice.
• Obtains sea surface temperatures globally through
  clouds.
• Determines depth of snow cover in large water
  basins.
• Measures amount of near-surface water in the soil
  of large agricultural areas.

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What can SMMR do with its ten channels?

• Greatly improves on ESMRs ability to obtain sea
  ice concentrations.
• Permits distinguishing between first-year and
  multiyear sea ice.
• Obtains sea surface temperatures globally through
  clouds.
• Determines depth of snow cover in large water
  basins.
• Measures amount of near-surface water in the soil
  of large agricultural areas.
• Can determine cloud water content and atmospheric
  water vapor.
• Makes observations of global rainfall rates.

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What can SMMR do with its ten channels?

• Greatly improves on ESMRs ability to obtain sea
  ice concentrations.
• Permits distinguishing between first-year and
  multiyear sea ice.
• Obtains sea surface temperatures globally through
  clouds.
• Determines depth of snow cover in large water
  basins.
• Measures amount of near-surface water in the soil
  of large agricultural areas.
• Can determine cloud water content and atmospheric
  water vapor.
• Makes observations of global rainfall rates.
• In what follows, we shall describe sea ice and
  SST observations.- Time-lapse movie of sea ice
  around Antarctica.- A record of multiyear sea
  ice concentrations.- Time-lapse movie of SST in
  the Indo-Pacific oceans.

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Low-pass filtered AA SICs
18-Year Record of Low-pass-filtered Sea Ice
Concentrations from the Nimbus-7 SMMR and the
SSMIs on the F-8, F-11 and F-13 DMSP Satellites,
showing the Antarctic Circumpolar Wave in the
interior of the ice pack.
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SST Anomalies of the Indo-Pacific Basin
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What is the legacy of ESMR and SMMR?

• They both contributed a significant part of the
  present 33-year sea ice coverage data set that
  has been used to investigate climate trends.
• SMMR has contributed a significant part of a
  25-year multiyear sea ice data that will also be
  important for climate change studies.

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32 years of the sea ice coverage record

• Arctic Antarctic

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24 years of multiyear sea ice observations
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Credits

• ESMR- Principal Investigator Thomas T.
  Wilheit- CoI Per Gloersen- Conceiver William
  Nordberg- Collaborators William J. Campbell,
  Alfred T.C. Chang
• SMMR- Instrument Scientist and Experiment Team
  Leader Per Gloersen- Team Members (sanctioned
  by Hqs) William J. Campbell (sea ice, ice
  sheets, snow) Ola M. Johannessen (sea ice,
  oceans) Kristina B. Katsaros (atmosphere) Klaus
  F. Kunzi (snow) Duncan B. Ross (oceans) David
  Staelin (atmosphere) E.P.L Windsor
  (oceans) Preben Gudmandsen (ice sheets) René O.
  Ramseier (sea ice)- Collaborators Donald J.
  Cavalieri, Alfred T.C. Chang, Thomas T.
  Wilheit Frank T. Barath (co-proposer), Edward
  Langham

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Continuing the tradition

• Special Sensor/Microwave Imager (SSMI)- A
  multispectral imager with similar channels to
  SMMR, but no 4.6 cm channel used for SST
  measurements- Flown on three different DOD/DMSP
  satellites- One month overlap with SMMR data -
  Has extended the sea ice record to 32 years

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Continuing the tradition

• Special Sensor/Microwave Imager (SSMI)- A
  multispectral imager with similar channels to
  SMMR, but no 4.6 cm channel used for SST
  measurements- Flown on three different DOD/DMSP
  satellites- One-month overlap with SMMR data-
  Has extended the sea ice record to 32 years
• Advanced Microwave Scanning Radiometer (AMSR-E)-
  Launched in 2002- Contains channels similar to
  SMMR plus two 3 mm channels- Has about twice the
  spatial resolution of SMMR SSMI