The influence of meteorology on rime and snow chemistry at a mountaintop site in northern California

Abstract

Samples of rime and snow were collected from 36 storm events during three winters at a high-elevation site in northern California. Trajectories for the 36 events were segregated into types characterized by either large zonal or large meridional extent. The hypothesis that events dominated by meridional flow (potentially bringing pollutants to the study site from pollutant source areas to the south) were associated with elevated ion concentrations in time was not substantiated. For both the combined 3-year period, and winter 1988–89 alone, Cl⁻, NO ⁻₃ , SO ²⁻₄ , and H⁺ concentrations in rime were greater generally than in snow, with the 3-year median concentrations for these ions ranging from 7 to 11 μeq L⁻¹ in rime, vs. 2 to 8 μeq L⁻¹ in snow. Intra-year variation in ion concentrations in rime was high during all three winters, with maximum concentrations during events in winter 1988–89 at least 16 times the magnitude of the minimum concentration for each ion.