Yu et al. (2026) Identification of the Global Cloud‐Clear Sky Transition Zone and Its Shortwave Radiation Effects

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2026
• Date: 2026-03-25
• Authors: Xinyu Yu, Qin Lang, Lunche Wang, Mengya Zhang, Shikuan Jin, Xihui Gu, Wen Xiao, Yu Du
• DOI: 10.1029/2025jd045352

Research Groups

Not explicitly stated in the abstract.

Short Summary

This study developed a globally consistent method to detect the Cloud-Clear Sky Transition Zone (CCTZ) over both land and ocean using MODIS data and radiative transfer modeling. It found that the CCTZ has a cloud-type-dependent spatial scale (approximately 5 km from clouds) and significantly enhances global mean diffuse shortwave radiation by 16.3% while reducing direct shortwave radiation by 0.8% compared to pure clear-sky conditions.

Objective

• To develop a globally consistent Cloud-Clear Sky Transition Zone (CCTZ) detection method applicable to both land and ocean.
• To analyze the effects of the CCTZ on direct and diffuse shortwave radiation across seven major cloud types.

Study Configuration

• Spatial Scale: Global, with 1 km spatial resolution.
• Temporal Scale: Not explicitly stated in the abstract, but implied to cover a period sufficient for statistical analysis of global CCTZ occurrence and radiative effects.

Methodology and Data

• Models used: Radiative transfer modeling.
• Data sources: Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations.

Main Results

• The CCTZ exhibits a globally coherent but cloud-type-dependent spatial scale, with a statistical boundary located approximately 5 km from clouds.
• The frequency of CCTZ occurrence is approximately 34% in "no-cloud" regions over land, which is significantly higher than over ocean (approximately 21%).
• Analysis of shortwave radiation responses, incorporating cloud classification, revealed three distinct mechanisms corresponding to distance from the nearest cloud:
  • Increasing-then-decreasing (Stratocumulus-Stratus, Cirrus)
  • Fluctuating (Altostratus-Altocumulus, Cumulus, Cumulonimbus)
  • Stable (Nimbostratus, Cirrus-Altocumulus-Altostratus)
• Compared to pure clear-sky conditions, the CCTZ enhances global mean diffuse shortwave radiation by approximately 16.3% and reduces direct shortwave radiation by approximately 0.8%, with magnitudes modulated by cloud type.

Contributions

• Developed a novel, globally consistent CCTZ detection method applicable to both land and ocean, overcoming limitations of previous land-constrained studies.
• Provided the first comprehensive analysis of CCTZ effects on direct and diffuse shortwave radiation, differentiating responses across seven major cloud types.
• Quantified the global mean radiative impact of CCTZ, showing a significant enhancement of diffuse shortwave radiation and a reduction in direct shortwave radiation.
• Highlighted the critical need for advanced cloud detection and more refined modeling of transition zones to improve the representation of these zones in climate systems and reduce uncertainties in global climate predictions.

Funding

Not available from the abstract.

Citation

@article{Yu2026Identification,
  author = {Yu, Xinyu and Lang, Qin and Wang, Lunche and Zhang, Mengya and Jin, Shikuan and Gu, Xihui and Xiao, Wen and Du, Yu},
  title = {Identification of the Global Cloud‐Clear Sky Transition Zone and Its Shortwave Radiation Effects},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2026},
  doi = {10.1029/2025jd045352},
  url = {https://doi.org/10.1029/2025jd045352}
}