Submillimeter Limb Sounder
The JPL Submillimeterwave Limb Sounder (SLS) is a heterodyne radiometer-spectrometer that measures the thermal emission spectra of gases in the Earth's upper atmosphere across a range of limb tangent altitudes. Abundance proles of stratospheric gases are inferred from these spectra using standard retrieval techniques.
The current instrument measures in the 600 to 700 GHz spectral interval using an NbTi superconductor-insulator-superconductor (SIS) double sideband quasioptical mixer and a broadly tunable local oscillator. The radiometric system noise temperature of the receiver system is approximately 280 K at IF band center. The down-converted 4 GHz wide IF band is spectrally resolved and power detected using analog filterbanks and digital spectrometers.
Instrument optics provide a