The CalWater field campaigns were designed to study how different sources of atmospheric aerosols impact clouds, precipitation processes, and the atmospheric rivers (ARs) hitting the California coast. A major focus involved characterizing the sources of ice-nucleating particles (INPs) to determine how they affect the phase, spatial distribution, and total amount of precipitation falling over California. Multiple aircrafts containing a suite of aerosol, cloud microphysics, and meteorological instrumentation sampled mixed-phase clouds over California. Aircraft measurements focused on determining the sources of aerosols seeding the clouds over different regions of California (Sierra Nevada mountain range, Central Valley, coast) under different meteorological conditions. Field measurements provide unique insight into how the transport of different aerosols can lead to changes in clouds and precipitation processes. This presentation will compare measurements of aerosol composition and sources from two aircraft campaigns in 2011 and 2015. Principally, major differences in the sources of aerosols seeding the ARs were observed during these two campaigns. ARs in 2011 were dominated by long-range transported dust, whereas in 2015, the AR clouds were seeded by marine aerosols. By incorporating remote measurements from satellites and ground-based precipitation profiling radars, we assess the factors affecting aerosol transport, and the resulting impacts on clouds and precipitation efficiencies.