Spatial Aggregation of Satellite Observations Leads to an Overestimation of the Radiative Forcing due to Aerosol-Cloud Interactions

The estimation of cloud radiative forcing (RFaci), arising from aerosol-cloud interactions (also known as the first indirect effect), relies on approximating cloud albedo susceptibility (β) to changes in droplet concentration. β depends on both cloud albedo and droplet concentration, which are observable through satellite observations. Typically, satellite data is spatially aggregated to coarser resolutions, such as 1 × 1° scenes. However, at these spatial scales, cloud albedo tends to be heterogeneous, while the β approximation assumes homogeneity. This study demonstrates that the common practice of aggregating satellite data and neglecting cloud albedo heterogeneity results in an average overestimation of 10% in previous RFaci estimates.