Supplementary material to "Tropospheric aerosols over the western North Atlantic Ocean during the winter and summer campaigns of ACTIVATE 2020: Life cycle, transport, and distribution"

Section S1: Model evaluation with surface aerosol concentrations, deposition fluxes, and MODIS AOD observations In this section we evaluate model simulations with surface aerosol concentration observations from the IMPROVE and CSN networks, aerosol deposition flux measurements from the NTN network of NADP, and satellite AOD measurements from MODIS/Aqua, with a focus on the eastern U.S. coastal region or WNAO.Aerosol surface concentrations.For comparison with model SNA surface concentrations, we use the IMPROVE/CSN observations obtained at 59 eastern U.S. sites (in the states of NY, CT, VA, MA, ME, GA, PA, DC, FL, NC, and SC), which are located upwind of the ACTIVATE flight area.Fig. S1 shows the scatterplots of IMPROVE/CSN daily surface concentrations of SNA aerosols versus corresponding model results at each of the selected sites for Feb.-Mar.(upper panels) and Aug.-Sep.(lower panels), respectively, 2020.The model results fromboth "standard" (blue triangles and lines) and "fixedCWC" (red triangles and lines) experiments (also see Table 1) are shown to help understand the impact of using MERRA-2 CWC on simulated aerosols in GEOS-Chem.Model daily output was sampled at the day, location, and site elevation for each data sample.In Feb.-Mar., for sulfate the standard model with MERRA-2 CWC has a small overall bias (0.6%) relative to the observations, with a reducedmajor-axis (RMA) regression slope of 0.80 and a correlation coefficient (R) value of 0.46.The fixedCWC simulation