28 Jan 2021

28 Jan 2021

Review status: this preprint is currently under review for the journal ESSD.

Observations of the downwelling far-infrared atmospheric emission at the Zugspitze observatory

Luca Palchetti1, Marco Barucci1, Claudio Belotti1, Giovanni Bianchini1, Bertrand Cluzet4, Francesco D'Amato1, Samuele Del Bianco5, Gianluca Di Natale1, Marco Gai5, Dina Khordakova3, Alessio Montori1, Hilke Oetjen7, Markus Rettinger2, Christian Rolf3, Dirk Schuettemeyer7, Ralf Sussmann2, Silvia Viciani1, Hannes Vogelmann2, and Frank Gunther Wienhold6 Luca Palchetti et al.
  • 1National Institute of Optics - CNR, Florence, Italy
  • 2Karlsruhe Institute of Technology, IMK-IFU, Garmisch-Partenkirchen, Germany
  • 3Forschungszentrum Jülich, Germany
  • 4Univ. Grenoble Alpes, Université de Toulouse, Météo-France, CNRS, Centre d’Études de la Neige, Grenoble, France
  • 5Institute of Applied Physics - CNR, Florence, Italy
  • 6Institute for Atmospheric and Climate Science - ETH, Zürich, Switzerland
  • 7ESA/ESTEC, Noordwijk, Netherlands

Abstract. Measurements of the spectrum of the atmospheric emission in the far-infrared (FIR) range, between 100 and 667 cm−1 (100–15 micron), are scarce because of the detection complexity and of the strong absorption of air at ground level, preventing the sounding of the FIR from low altitude. Consequently, FIR measurements need to be made from high-altitude sites or on board airborne platforms or satellites. This paper describes the dataset of FIR spectral radiances of the atmosphere and snow surface emission, measured in the 100–1000 cm−1 range by the Far-Infrared Radiation Mobile Observation System (FIRMOS) instrument, during a 2-month campaign carried out from ground at 3000 m of altitude, on the top of Mount Zugspitze in the German Alps, in 2018–2019. This campaign is part of the preparatory activity of a new space FIR mission, named Far-infrared-Outgoing-Radiation Understanding and Monitoring (FORUM), which is under development by the European Space Agency (ESA). The dataset acquired during the campaign also includes all the additional measurements needed to provide a full characterisation of the observed atmospheric state and the local atmospheric and surface conditions. It includes co-located spectral measurements in the infrared range from 400 to 1800 cm−1; lidar backscatter profiles; radiosoundings of temperature, humidity and aerosol backscatter profiles; local weather parameters; and snow/ice microphysical properties. These measurements provide a unique dataset that can be used to perform radiative closure experiments to improve modelling parameters that in the FIR are not well characterised, such as water vapour spectroscopy, scattering properties of cirrus clouds and the FIR emissivity of the surface covered by snow. The consolidated dataset is freely available via the ESA campaign dataset website at

Luca Palchetti et al.

Status: open (until 11 Apr 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on essd-2020-377', Xianglei Huang, 04 Mar 2021 reply

Luca Palchetti et al.

Data sets

FIRMOS - Technical Assistance for a Far-Infrared Radiation Mobile Observation System (EE9 Forum) Luca Palchetti, Marco Barucci, Claudio Belotti, Giovanni Bianchini, Bertrand Cluzet, Francesco D'Amato, Samuele Del Bianco, Gianluca Di Natale, Marco Gai, Dina Khordakova, Alessio Montori, Hilke Oetjen, Markus Rettinger, Christian Rolf, Dirk Schuettemeyer, Ralf Sussmann, Silvia Viciani, Hannes Vogelmann, and Frank Gunther Wienhold

Luca Palchetti et al.


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Short summary
The FIRMOS far-IR prototype, developed for the preparation of the ESA FORUM mission, was deployed for the first time at the Zugspitze Mt at 3000 m of altitude to measure the far-IR spectrum of the atmospheric emission. The measurements, including co-located radiometers, LiDARs, radiosoundings, weather and surface properties, provide an unique dataset to study radiative properties of water vapour, cirrus clouds, and snow emissivity over the infrared emission, including the under-explored far-IR.