A 5-year (2010–2014) quasi-global simulation from the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) has been analyzed to study distribution characteristics and sources of aerosols associated with atmospheric rivers (ARs) over the western United States. The model simulation can well detect the AR events and realistically capture the PM₁₀ mass and precipitation water on AR days through compared with MERRA-2 reanalysis. Generally, aerosols can be transported along with ARs over the northwestern Pacific and reach the west coast of North America. These transports are mainly associated with the weakened subtropical ridges and enhanced southwesterly low-level flows ridges over North Pacific. The ARs can bring positive contributions on rainfall and more PM₁₀ mass from trans-Pacific transport and the United States is removed through wet deposition on AR days. However, the impact of ARs on the trans-Pacific transported aerosol contribution fractions is positive, because the aerosols from trans-Pacific transport suspend at higher altitude and can be scavenged relatively fewer. Moreover, the impact of ARs on PM₁₀ mass fraction over the California region is mainly at 1-4 km with a value range of 6-15%, which is dominated by the dust, followed by the sulfate. This study investigates the impact of ARs on the aerosols from trans-Pacific transport and the United States and displays the importance of aerosols and ARs for predicting heavy precipitation and extreme snowfall in cool seasons over the west United States.

WRF-Chem,trans-Pacific transported aerosol,atmospheric river,source contribution,PM10 mass concentration