A new dataset has been released for the FINESSE at Andøya campaign, which took place in Norway in 2023.

ESA conducts airborne and ground-based campaigns to support the development of new instruments, and calibration and validation of existing instruments. These campaigns simulate satellite-based instruments and are conducted all over the world in support of a wide range of applications.

The Andøya campaign supported the upcoming Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission, which has been selected as ESA’s ninth Earth Explorer. FORUM will help evaluate the role that the far-infrared part of the electromagnetic spectrum plays in shaping our climate.

To support FORUM, the Far-infrared Spectrometer for Surface Emissivity (FINESSE) was deployed at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) in Norway. FINESSE is a new Fourier Transform Spectrometer and was used to measure far-infrared emissivity of ice and snow surfaces in an Arctic environment.

The deployment of FINESSE was able to piggy-back on the existing MC2-ICEPACKS campaign organised by the University of Oslo. The aim of the MC2-ICEPACKS campaign was to investigate the distribution of Arctic cloud phase and - based on the results of the campaign - to further constrain Earth System Models. The MC2-ICEPACKS campaign consisted of a ground-based segment and airborne measurements facilitated by INCAS’ (National Institute for Aerospace Research of Romania) ATMOSLAB (Atmospheric Research Laboratory) aircraft.

FINESSE measurements were complemented by in-situ sampling of cirrus cloud microphysical properties from an aircraft, lidar measurements from ALOMAR Observatory, and radiosondes released each day near Andenes airport.

The campaign took place between 6 February and 17 March 2023, and gathered radiance spectra data in the spectral range 400 to 1,600 cm-1 (6.3 to 25 μm). The goals of the campaign were to:

• Measure the downwelling radiative signatures of ice clouds co-incident with in-situ measurements from aircraft
• Measure the radiance emitted by snow and ice surfaces for the retrieval of far-infrared surface emissivity
• Measure the downwelling radiance of other scenes

The pressure, air temperature, humidity, and CO2 concentration in the vicinity of the interferometer were also recorded.

FINESSE successfully worked in the cold and windy Arctic conditions, and the campaign was conducted during a period forecast to have mostly clear skies, which aided measurements.

The campaign delivered a calibrated radiance dataset in NetCDF format, which is suitable for inversion for retrieval of atmospheric or surface properties. The dataset can also be used to retrieve far-infrared emissivity of ice and snow surfaces, and test the performance of ice cloud models in the far-infrared, which are both applications that the FORUM mission will address.

Data acquired during the campaign are openly available for download following submission of a data access request.

Learn more about the FINESSE at Andøya campaign and how to request the data.