Significant underestimation of radiative forcing by aerosol-cloud interactions derived from satellite-based methods

Area of Science:

• Atmospheric science
• Climate science
• Remote sensing

Background:

• Satellite estimates of radiative forcing by aerosol-cloud interactions (RF_aci) are consistently lower than global model outputs.
• This discrepancy hinders accurate climate change projections.

Purpose of the Study:

• To reduce the discrepancy between satellite-based and model-based RF_aci estimates.
• To improve the accuracy of satellite-derived climate forcing data.

Main Methods:

• Correcting for sampling biases in satellite measurements that exclude high cloud fraction clouds.
• Utilizing fine-mode aerosol optical depth (AOD) as a proxy for cloud condensation nuclei (CCN).

Main Results:

• Accounting for sampling biases increased global RF_aci by 55% (133% over land, 33% over ocean).
• Switching to fine-mode AOD further increased RF_aci to -1.09 W m^-2.
• The corrected RF_aci shows a substantial increase, particularly over land, resolving a key difference with climate models.

Conclusions:

• Satellite measurement biases significantly underestimate the cooling effect of aerosol-cloud interactions.
• Corrected satellite estimates of RF_aci align better with global climate models, improving climate change projections.