SPATIAL AND TEMPORAL VARIABILITY OF RIME ICE AND SNOW CHEMISTRY AT 5 SITES IN CALIFORNIA

Snow collected on the ground and rime ice collected on surrogate surfaces at five sites in California were analyzed for major ion concentrations during winters 1986-1987 and 1987-1988. Temporal variation in rime chemistry was large, with maximum values 5-40 times the magnitude of minimum values during winter 1987-1988. Mean concentration differences among rime events at individual locations were often as large as mean differences among sites. On the local scale, no significant differences in rime and snow mean concentrations of H+, NO3-, SO42-, Cl-, Na+, K+, Mg2+ and Ca2+ were identified at three nearby sites in the central Sierra Nevada. Among sites in central and northern California, and immediately downwind of the Los Angeles basin, mean SO42-, Cl- and Ca2+ solute concentrations in rime were significantly greater at the southern California location during the winter of 1987-1988. The mean concentration of NO3- in rime at the southern California site was 2-8 times as high as in the central and northern California sites, but was not significantly different because of variation between rime events at all sites. Between the winters of 1986-1987 and 1987-1988 mean concentrations of K+, Mg2+, and Ca2+ in rime and snow samples from most sites differed significantly, largely because winter 1987-1988 concentrations of these constituents were low or undetectable in many samples. During both winters mean concentrations of H+, NO3-, SO42-, Cl-, Na+, K+, Mg2+ and Ca2+ were higher in rime samples than in snow samples collected concurrently.