WMO OSCAR | Details for Instrument SMMR

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Instrument: SMMR

Instrument details

Acronym	SMMR
Full name	Scanning Multichannel Microwave Radiometer)
Purpose	Multi-purpose MW imagery
Short description	5-frequency / 10-channel MW radiometer operating in the range 6.6-37 GHz [see detailed characteristics below]
Background	Prototype of multi-channel conical scanning MW imagers
Scanning Technique	Conical scanning, 15 rpm (26 km/line), 50.2° incidence angle, swath 780 km
Resolution	Changing with frequency, ranging from 22 km at 37 GHz to 120 km at 6.6 GHz, consistent with a 80-cm antenna diameter
Coverage / Cycle	Global in 2 days
Mass	52.3 kg	Power	60 W	Data Rate	2 kbps

Providing Agency	NASA
Instrument Maturity	Flown on an R&D satellite
Utilization Period:	1978 to 1994
Last update:	2012-11-29

Detailed characteristics

Central frequency (GHz)	Bandwidth (MHz)	Polarisations	NEΔT	IFOV	Pixel
6.6	250	V, H	0.9 K	95x160 km	40x26 km
10.7	250	V, H	0.9 K	60x100 km	20x26 km
18.0	250	V, H	1.2 K	35x60 km	20x26 km
21.0	250	V, H	1.5 K	30x50 km	20x26 km
37.0	250	V, H	1.5 K	17x29 km	10x26 km

Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Nimbus (NASA)
- Nimbus-7 (see instrument status) Jan 1979 - Aug 1994
SeaSat (NASA)
- SeaSat (see instrument status) Sep 1978 - Oct 1978

Instrument classification

Earth observation instrument
Passive microwave radiometer
Conical scanning microwave radiometer

WIGOS Subcomponents

Subcomponent 1
MW imagery [in SSO]
MW imager [in SSO]

Mission objectives

Primary mission objectives

Sea surface temperature
Sea-ice cover
Wind speed (near surface)

Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
Note: * Primary mission objective.

Search:

Variable	Relevance for measuring this variable	Operational limitations	Explanation
Snow status (wet/dry)	2 - very high	Coarse spatial resolution.	MW channels around 19 and 37 GHz
Snow water equivalent	2 - very high	Coarse spatial resolution.. Ground stations network needed.	MW channels around 19 and 37 GHz
Wind speed (near surface)*	2 - very high	Over sea only.	MW channels around 7, 10, 19 and 37 GHz
Biomass	3 - high	Index only.. Coarse spatial resolution.	Derived from differential effect of vegetation across MW frequencies around 7, 10 and 19 GHz
Cloud liquid water (CLW)	3 - high	No specific limitation.	MW channels around 37 GHz
Cloud liquid water (CLW) total column	3 - high	No specific limitation.	MW channels around 37 GHz
Long-wave Earth surface emissivity	3 - high	Long time series needed.	MW channels around 7, 10, 19 and 37 GHz. Emissivity across this MW range inferred by statistical analysis
Sea surface temperature*	3 - high	No specific limitation.	MW channels around 7 and 10 GHz
Snow cover	3 - high	Coarse spatial resolution.	MW channels around 19 and 37 GHz
Soil moisture at surface	3 - high	Coarse spatial resolution.. Affected by vegetation.	MW channels around 7 and 10 GHz
Integrated Water Vapour (IWV)	3 - high	Over sea only.	MW channel(s) in the water vapour band around 23 GHz
Soil moisture (in the roots region)	4 - fair	Coarse spatial resolution.. Affected by vegetation.	MW channels around 7 GHz. Assimilation process required
Sea-ice cover*	4 - fair	No specific limitation.	MW channels around 7, 10, 19 and 37 GHz
Accumulated precipitation	5 - marginal	Poor time sampling.. Time sampling to be interpolated by GEO.	MW channels around 10, 19, 23 and 37 GHz
Land surface temperature	5 - marginal	Coarse spatial resolution.	MW channels around 7 and 10 GHz
Precipitation intensity at surface (liquid or solid)	5 - marginal	Inaccurate over land.	MW channels around 10, 19, 23, and 37 GHz; 10 GHz very important for heavy precipitation over the sea
Sea-ice type	5 - marginal	No specific limitation.	MW channels around 7, 10, 19 and 37 GHz. Type interpreted as age/roughness

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