资源环境科技发展态势分析平台

Here we use 16‐year satellite and reanalysis data in combination with a multivariate regression model to investigate how aerosols affect cloud fraction (CF) over the East Coast of the United States. Cloud droplet number concentrations (N_d), cloud geometrical thickness, lower tropospheric stability, and relative humidity at 950 hPa (RH₉₅₀) are identified as major cloud controlling parameters that explain 97% of the variability in CF. N_d is shown to play an important role in regulating the dependence of cloud fraction on RH₉₅₀. The observed annual‐mean CF shows no significant trend due to the cancelation from the opposite trends in N_d and RH₉₅₀. The multivariate regression model revealed that the decline in N_d alone would lead to a about 20% relative decline in CF. Our results indicate the significant aerosol effects on CF and suggest the need to account for pollution‐induced cloud changes in quantifying cloud feedback based on long‐term observations.