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Cloud attenuation estimation based on cloud particle sensor sonde observations for next-generation satellite
Takahiro Ohno1,2, Munehiro Matsui3, Kiyohiko Itokawa3
1Access Network Service Systems Laboratories, NTT, Inc., Yokosuka, 239-0847, Japan. takahiro.ohno@ntt.com.
Scientific Reports
|July 8, 2026
Summary
Cloud attenuation in satellite communications is significantly impacted by ice crystals, not just water droplets, especially at shorter wavelengths. This study uses in-situ cloud particle data to show ice crystals dominate attenuation, challenging existing models.
Area of Science:
- Satellite Communications
- Atmospheric Science
- Radiowave Propagation
Background:
- Cloud attenuation impacts sub-terahertz (sub-THz), terahertz (THz), and free-space optical (FSO) satellite communications.
- Existing models like ITU-R often overlook ice crystals, relying on liquid water content, which can lead to inaccurate estimates in multilayered clouds.
Purpose of the Study:
- To estimate cloud attenuation up to 10 THz using in-situ cloud microphysical data.
- To explicitly account for both water droplets and ice crystals in attenuation estimations.
- To evaluate the limitations of current cloud attenuation models.
Main Methods:
- Utilized cloud particle sensor (CPS) sonde data from Okinawa, Japan.
- Measured vertical profiles of cloud particle types (water droplets, ice crystals) and their size distributions.
- Calculated cloud attenuation based on in-situ observational data.
Main Results:
- Cloud attenuation is dominated by ice crystals, particularly at wavelengths below 1.0 mm.
- This finding challenges the conventional assumption that water droplets are the primary cause of attenuation.
- Explicit consideration of ice crystal size distribution is crucial for accurate modeling.
Conclusions:
- In-situ cloud particle observations reveal ice crystals significantly influence cloud attenuation in satellite communication frequencies.
- Conventional models may overestimate or underestimate attenuation due to their limited consideration of ice crystal effects.
- Further global studies are needed to develop more accurate and universally applicable cloud attenuation models for satellite communications.
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