# Presentation: 893459

## Imaging Microwave Radiometers in Space

- Per Gloersen
- Oceans and Ice Branch (971)

## The Nimbus Microwave Imager Heritage

## The Nimbus Microwave Imager Heritage

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

## 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.

## 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.

## 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.

## 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.

## 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.

## 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.

## 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.

## 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.

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

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

## The Nimbus 7 SMMR

- Launched in October 1978
- Turned off in August 1987

## 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 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

## 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.

## What can SMMR do with its ten channels?

- Greatly improves on ESMR’s ability to obtain sea ice concentrations.

## What can SMMR do with its ten channels?

- Greatly improves on ESMR’s ability to obtain sea ice concentrations.
- Permits distinguishing between first-year and multiyear sea ice.

## What can SMMR do with its ten channels?

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

## What can SMMR do with its ten channels?

- Greatly improves on ESMR’s 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.

## What can SMMR do with its ten channels?

- Greatly improves on ESMR’s 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.

## What can SMMR do with its ten channels?

- Greatly improves on ESMR’s 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.

## Low-pass filtered AA SICs

## SST Anomalies of the Indo-Pacific Basin

**SST Anomalies of the Indo-Pacific Basin**

## 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.

## 32 years of the sea ice coverage record

-    	  Arctic			    Antarctic

## 24 years of multiyear sea ice observations

## 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

## 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

## 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