Spectral signatures of zenith sky radiance from surface-based sky radiometers: implications for clear- and cloudy-sky detection

Khatri, Pradeep; Irie, Hitoshi; Kobayashi, Hiroshi; Morino, Isamu; Jin, Yoshitaka; Hayasaka, Tadahiro; Iwabuchi, Hironobu; Takamura, Tamio; Takayama, Yoshiki

doi:10.5194/amt-19-6447-2026

Articles | Volume 19, issue 19

https://doi.org/10.5194/amt-19-6447-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

SKYNET – the international network for aerosol, clouds,...

https://doi.org/10.5194/amt-19-6447-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 19

Research article

|

14 Oct 2026

Research article |

| 14 Oct 2026

Spectral signatures of zenith sky radiance from surface-based sky radiometers: implications for clear- and cloudy-sky detection

Pradeep Khatri, Hitoshi Irie, Hiroshi Kobayashi, Isamu Morino, Yoshitaka Jin, Tadahiro Hayasaka, Hironobu Iwabuchi, Tamio Takamura, and Yoshiki Takayama

Data sets

MOD35_L2 - MODIS/Terra Cloud Mask and Spectral Test Results 5-Min L2 Swath 250m and 1km S. Ackermann et al. https://doi.org/10.5067/MODIS/MOD35_L2.061

MYD35_L2 - MODIS/Aqua Cloud Mask and Spectral Test Results 5-Min L2 Swath 250m and 1km S. Ackermann et al. https://doi.org/10.5067/MODIS/MYD35_L2.061

MOD06_L2 - MODIS/Terra Clouds 5-Min L2 Swath 1km and 5km S. Platnick et al. https://doi.org/10.5067/MODIS/MOD06_L2.061

MYD06_L2 - MODIS/Aqua Clouds 5-Min L2 Swath 1km and 5km S. Platnick et al. https://doi.org/10.5067/MODIS/MOD06_L2.061

Short summary

This study investigates the spectral characteristics of zenith sky radiances under clear- and cloudy-sky conditions using SKYNET sky radiometer observations. It proposes a simple, physically interpretable method for distinguishing sky states and demonstrates that wavelength-dependent radiance information can support reliable sky-state detection across diverse atmospheric environments.