Insturment Summary

The FarINfrarEd Spectrometer for Surface Emissivity (FINESSE) combines a commercial Bruker EM27 with a bespoke front-end pointing and calibration system designed and built at Imperial College. The instrument can routinely measure upwelling and downwelling radiation over the range 6.25-25 microns with the primary goal of retrieving surface emissivity. Secondary applications include the ability to use the up-looking views to retrieve water vapour and cloud properties. Compared to existing instrumentation, the relatively fast scan speed of the instrument is advantageous if conditions are changing rapidly.

To date, FINESSE has been characterised in the laboratory and used to assess the variation of the emissivity of de-ionised water with view angle and surface temperature. It participated in its first field campaign in November 2023, deploying to the ALOMAR ground-station in Andoya, Norway to measure the emissivity of varying snow and ice conditions (more details). Further deployments are expected to follow.


  • Four port, Michelson interferometer
  • Spectral range: 6.25-25 microns
  • Flexible spectral resolution, maximum: 0.5 cm-1
  • Hardened down to 253 K
  • Comes with custom built GUI and external environmental sensors for H2O, CO2 and air temperature
  • Science Lead: Prof. Helen Brindley, NCEO, Imperial College London
  • Project Scientist: Dr Jon Murray, Imperial College London
  • Funding Agency: NERC


FINESSE in the laboratory (Credit: Laura Warwick)