McKinnon et al. (2025) Observed and Modeled Trends in Downward Surface Shortwave Radiation Over Land: Drivers and Discrepancies

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

Identification

• Journal: Geophysical Research Letters
• Year: 2025
• Date: 2025-12-23
• Authors: Karen A. McKinnon, Isla R. Simpson
• DOI: 10.1029/2025gl119493

Research Groups

Not explicitly stated in the abstract.

Short Summary

This study validates ERA5 incoming surface shortwave radiation (Rs) against satellite and in situ data, then reveals substantial global continental brightening from 1980 to 2024, often linked to cloud cover reductions rather than aerosols, and highlights significant discrepancies with CMIP6 climate model simulations.

Objective

• To demonstrate the favorable agreement of ERA5 incoming surface shortwave radiation (Rs) variability and trends with high-quality satellite and in situ estimates.
• To show evidence of substantial continental brightening from 1980 to 2024 and investigate its drivers (aerosols vs. clouds).
• To compare observed Rs and cloud cover trends with an ensemble of CMIP6-era climate model simulations.

Study Configuration

• Spatial Scale: Global land areas, with specific regional examples (e.g., central United States, Brazil, central Asia).
• Temporal Scale: Multidecadal trends and variability, specifically from 1980 to 2024.

Methodology and Data

• Models used: ERA5 (reanalysis), CMIP6-era climate model simulations (ensemble of 237).
• Data sources: Satellite estimates, in situ observations, ERA5 reanalysis, aerosol concentration data (implied for comparison).

Main Results

• The variability and trends in ERA5 incoming surface shortwave radiation (Rs) agree favorably with high-quality estimates from satellite and in situ sources.
• Substantial continental brightening was observed globally from 1980 to 2024.
• This brightening includes regions like the central United States, Brazil, and central Asia, which do not show large trends in aerosol concentrations over the same period.
• The brightening in these regions is co-located with reductions in total cloud cover.
• Trends in both Rs and total cloud cover are at the edge or entirely outside the range of an ensemble of 237 CMIP6-era climate model simulations.
• The spatial pattern of trends in CMIP6 models more directly reflects the pattern of aerosol concentrations, contrasting with observations in some regions.

Contributions

• Provides a global analysis of multidecadal trends in incoming surface shortwave radiation over land, validated by high-quality observational data.
• Identifies significant continental brightening from 1980 to 2024, demonstrating that cloud cover reductions, not solely aerosols, are a key driver in many regions.
• Reveals a substantial discrepancy between observed (ERA5) trends in Rs and cloud cover and those simulated by CMIP6 climate models, highlighting potential areas for model improvement in representing cloud-radiation interactions or their drivers.

Funding

Not available in the abstract.

Citation

@article{McKinnon2025Observed,
  author = {McKinnon, Karen A. and Simpson, Isla R.},
  title = {Observed and Modeled Trends in Downward Surface Shortwave Radiation Over Land: Drivers and Discrepancies},
  journal = {Geophysical Research Letters},
  year = {2025},
  doi = {10.1029/2025gl119493},
  url = {https://doi.org/10.1029/2025gl119493}
}