Achieving consistency between in-situ and remotely sensed optical and microphysical properties of Arctic cirrus: the impact of far-infrared radiances

Year: 2026

Authors: Di Natale G., Brindley H., Warwick L., Panditharatne S., Yang P., David RO., Carlsen T., Vwjwiac SN., Vlad A., Ghemulet S., Bantges R., Foth A., Flugge M., Lyngra R., Oetjen H., Schuettemeyer D., Palchetti L., Murray J.

Autors Affiliation: Natl Inst Opt, Consiglio Nazl Ric, Via Madonna Piano 10, I-50019 Firence, Italy; Imperial Coll London, Dept Phys, London, England; Imperial Coll, Natl Ctr Earth Observat, London, England; ESA, Estec, Noordwijk, Netherlands; Harwell Oxford, RAL Space, Chilton, England; Texas A&M Univ, Dept Atmospher Sci, College Stn, TX 77843 USA; Univ Oslo, Dept Geosci, Oslo, Norway; Natl Inst Aerosp Res Elie Carafoli, Bucharest, Romania; Univ Bucharest, Fac Phys, 405 Atomistilor, Magurele 077125, Romania; Univ Leipzig, Leipzig Inst Meteorol, Leipzig, Germany; Andoya Space, Andoya, Norway.

Abstract: This paper explores whether it is possible to achieve consistency between ground-based infrared radiance measurements made in the presence of cirrus, co-located in-situ aircraft measurements of the cirrus microphysics, and ancillary ground-based remote sensing. Specifically we use spectrally resolved radiances covering the range 400-1500 cm(-1), in-situ measurements of cirrus particle sizes and habits, backscatter ceilometer observations of cloud vertical structure and microwave inferred temperature and humidity profiles to investigate whether we can obtain consistency between the derived cloud properties and atmospheric state from these independent sources of data. The primary focus of this study is on the sensitivity of the retrieved cloud particle size to the assumed crystal habit. Excellent consistency between the retrieved cloud parameters is achieved both with the ceilometer derived optical depth and the size distribution measured by the aircraft by assuming the crystal habit to be comprised of bullet rosettes. The averaged values of the effective diameter and optical depth obtained from radiometric measurements are (26.5 +/- 1.8) mu m and (0.12 +/- 0.01) in comparison with the values derived from in-situ and ceilometer measurements equal to (31.5 +/- 5.0) mu m and (0.13 +/- 0.01), respectively. Furthermore, we show that the radiance information contained within the far-infrared (wavenumbers < 650 cm(-1)) spectrum is critical to achieving this level of agreement with the in-situ aircraft observations. The results emphasize why it is vital to expand the current limited database of measurements encompassing the far-infrared spectrum, particularly in the presence of cirrus, to explore whether this finding holds over a wider range of conditions. Journal/Review: ATMOSPHERIC CHEMISTRY AND PHYSICS

Volume: 26 (2)      Pages from: 1373  to: 1394

More Information: We would like to acknowledge the European Research Council (StG 758005 (Mixed-Phase Clouds and Climate) and CoG 101045273 (STEP-CHANGE)), EEA Grants/Norway Grants (grant no. EEARO-NO-2019-0423/IceSafari, contract no. 31/2020) and EU-HORIZON-WIDERA-2021 (Grant 101079385 (BRACE-MY)) for supporting the campaign and airborne data analysis. We are also grateful to the INCAS pilots, the staff at Andoya Space and the Norwegian Meteorological Institute for their support during the campaign. Funding for the deployment of FINESSE was provided by the European Space Agency (ESA) under contract no. 4000137153/22/NL/IA. HB, JM and RB were supported by the UK Natural Environment Research Council grant no. NE/Y006216/1. Part of the research activities described in this paper were carried out with contribution of the Next Generation EU funds within the National Recovery and Resilience Plan (PNRR), Mission 4 – Education and Research, Component 2 – From Research to Business (M4C2), Investment Line 3.1 – Strengthening and creation of Research Infrastructures, Project IR0000038 – Earth Moon Mars (EMM). EMM is led by INAF in partnership with ASI and CNR. We gratefully acknowledge the funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – project no. 268020496 – TRR 172, within the Transregional Collaborative Research Center ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3. Finally, we also thank the Norwegian Meteorological Institute for making the Ceilometer data available.
KeyWords: Radiative Properties; Cloud Properties; Water-vapor; Part I; Absorption; Climate; Scattering; Retrieval; Algorithm; Inversion
DOI: 10.5194/acp-26-1373-2026