EGU25-18469, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-18469
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Modeling the Dielectric Constant of Seawater from 0.4 GHz to 2 GHz: A feasbility study for the CryoRad mission
Yiwen Zhou1, Jacqueline Boutin2, David Le Vine3, Roger Lang4, Marco Brogioni5, Giovanni Macelloni5, and Matthias Drusch6
Yiwen Zhou et al.
  • 1Swiss Federal Research Institute WSL, Switzerland (yiwen.zhou@wsl.ch)
  • 2Laboratoire d'Océanographie Dynamique et de Climatologie/CNRS, France
  • 3NASA Goddard Space Flight Center, USA
  • 4The George Washington University, USA
  • 5Istituto di Fisica Applicata "N. Carrara", National Research Council of Italy, Italy
  • 6European Space Agency, The Netherland

CryoRad, a candidate mission under ESA’s Earth Explorer 12 program, is designed to carry an advanced wideband, low-frequency microwave radiometer operating from P- to L-band (0.4 to 2 GHz). One of the primary objectives of CryoRad is to enhance sea surface salinity (SSS) retrieval, particularly in cold water regions which are of increasing importance due to climate change. This improvement is because of the great sensitivity of P-band brightness temperature to changes in sea surface salinity. Achieving this objective hinges on the development of an accurate dielectric constant model for seawater over the entire frequency range of 0.4 to 2 GHz in order to compute the sea surface emissivity and retrieve SSS.

Over the past decade, progress has been made in the accurate measurement [1] and modeling of seawater dielectric constants at L-band (1.413 GHz) [2][3][4]. These efforts have been directed at improving SSS retrieval accuracy using data from satellite missions such as SMOS [5] and Aquarius [6]. Recently, the new P-band seawater dielectric measurements (0.707 GHz) [7] enable the possibility of using the data at the two frequencies to develop a new dielectric constant model, which is expected to provide insight into the dielectric constant of seawater across the entire frequency range of the CryoRad mission and its application in multi-frequency SSS retrieval.

This paper introduces the development of this wideband seawater dielectric constant model and its validation against experimental measurement data. A sensitivity analysis is also presented to highlight the benefits of using an accurate dielectric constant model over the frequency range. These results demonstrate the potential of the new model to support the CryoRad mission as well as future missions operating within this frequency band to improve multi-frequency SSS retrieval.

[1] R. Lang, Y. Zhou, C. Utku, and D. Le Vine (2016), “Accurate measurements of the dielectric constant of seawater at L-band”, Radio Science, vol: 51, pp. 2-24.

[2] Y. Zhou, R. Lang, E. Dinnat and D. Le Vine (2021), “Seawater Debye Model Function at L-band and Its Impact on Salinity Retrieval from Aquarius Satellite Data”, IEEE TGRS, vol. 59, no. 10 pp. 1-14. 

[3] D. Le Vine, R. Lang, Y. Zhou, E. Dinnat and T. Meissner (2022), “Status of the dielectric constant of sea water at L-Band for remote sensing of salinity”, IEEE TGRS, vol. 60, 4210114

[4] J. Boutin et al. (2023), “New seawater dielectric constant parametrization and application to SMOS retrieved salinity”, IEEE TGRS, vol. 61, 2000813

[5] Y. Kerr, et al. (2010), "The SMOS mission: New tool for monitoring key elements of the global water cycle." Proc. IEEE 98(5): 666–687

[6] D. M. Le Vine, G. Lagerloef and S.E. Torrusio (2010), “Aquarius and Remote Sensing of Sea Surface Salinity from Space”, Proc. IEEE, vol. 98, no. 5, pp. 688-703

[7] D. M. Le Vine, R. Lang, M. Li, E. Dinnat, J. Boutin and Y. Zhou (2025), “The Dielectric Constant of Sea Water at P-Band for Salinity from 0 to 150 pss”, IEEE TGRS, Early Access, 2025

How to cite: Zhou, Y., Boutin, J., Le Vine, D., Lang, R., Brogioni, M., Macelloni, G., and Drusch, M.: Modeling the Dielectric Constant of Seawater from 0.4 GHz to 2 GHz: A feasbility study for the CryoRad mission, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18469, https://doi.org/10.5194/egusphere-egu25-18469, 2025.