COARSE-PARTICLE AND FINE-PARTICLE ATMOSPHERIC NITRATE AND HNO3(G), IN CLAREMONT, CALIFORNIA, DURING THE 1985 NITROGEN SPECIES METHODS COMPARISON STUDY

Coarse ( less than equivalent to 1. 5 mu m) atmospheric particle nitrates were measured along with HNO//3(g) in 40 consecutive periods over the 8 days of the 1985 Nitrogen Species Methods Comparison Study in Claremont, California, in September 1985. HNO//3(g) and fine-particle nitrate both showed pronounced (approx. 10-fold) diurnal variations with a mild-morning peak in the case of fine-particle nitrate and a mid-afternoon peak in the case of HNO//3(g). Coarse-particle nitrate showed relatively little diurnal variation. Time-average values over the whole experiment for HNO//3(g), fine nitrate, and coarse nitrate were, respectively, 114, 128 and 114 nanamole m** minus **3.