AbstractAbstract
Sulfate burden over the North Atlantic Ocean (NATL) exhibits strong seasonality despite no seasonality in anthropogenic sulfur dioxide (SO
2
) emissions. However, the seasonality of sulfate aerosols over NATL has decreased since 1970, likely due to a reduction in the United States (US) SO
2
emissions following the Clean Air Act of 1970. We performed atmospheric chemistry and transport simulations to assess the impact of changing US SO
2
emissions between 1970 and 2010 on NATL sulfate burden and radiative forcing. United States SO
2
emission reductions weakened the seasonality in NATL sulfate burden by ∼17%, primarily due to a decrease in chemical production and transport in summer. These emission reductions caused a summertime radiative forcing (∼2 W m
−2
) twice as large as the wintertime forcing. Our findings highlight the complex, season‐dependent responses of sulfate burden and radiative effects to regional emission changes.
