Aura MLS Instrument

Instrument Science

The EOS MLS measures thermal emission from broad spectral bands centered near 118, 190, 240, 640 and 2500 GHz.

They are measured continuously (24 hours per day) by 7 microwave receivers (2 each at 118 and 2500 GHz) using a limb viewing geometry, which maximizes signal intensities and vertical resolution.

MLS is radiometrically calibrated after each 25 second limb scan. Design lifetime is 5 years of continuous operation.

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Instrument Modules

The EOS MLS instrument contains three modules:

1. The GHz radiometer module, which includes the 118 through 640 GHz receivers and a scanning offset antenna with 0.8 x 1.6 m primary mirror.
2. The THz radiometer module which contains the 2500 GHz receivers and the THz telescope and scan mirror, whose scan is synchronized with that of the GHz antenna.
3. The Spectrometer module which receives signals from the GHz and THz radiometer modules, detects and digitizes them, and passes the digitized signals to the spacecraft for telemetry to the ground.

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MLS Radiometers and Data Products

Radiometer	Primary Data Products	Additional Data Products
118 GHz	Geopotential Height Temperature	Tangent Pressure IWC IWP
190 GHz	H2O HCN HNO3 (upper troposphere) N2O* RHi	CH3CN (lower quality than from 640 GHz) ClO (lower quality than from 640 GHz) IWC IWP N2O (lower quality than from 640 GHz) O3 (but not in the upper troposphere) Volcanic SO2
240 GHz	CO HNO3 (upper troposphere & lower stratosphere) IWC IWP O3 Volcanic SO2	Improves quality of upper trop H2O
640 GHz	BrO CH3Cl CH3CN CH3OH ClO HCl HO2 HOCl Volcanic SO2	CH3CN HNO3 IWC IWP N2O Stratospheric O3 (with better vertical resolution than 240 GHz (but not in upper troposphere) Improves quality of upper trop H2O
2.5 THz	OH	O3 (lower quality than from other radiometers)

*For v4 and later, the standard N₂O product comes from the 190 GHz. The 640 GHz N₂O product is of slightly higher quality than the 190 GHz, but the record ends in June 2013.