Cloud chemistry research at Whiteface Mountain

Abstract

Cloud collection principles are briefly reviewed; the performance of two collectors in common use is compared. Two cloud event studies (one during winter, the other during summer) are presented to contrast typical time-dependent histories of chemical concentrations for the two seasons. During winter, the oxidation rate of SO2 is low, resulting in measured sulfate concentrations independent of SO2 concentrations. During summer, SO2 is rapidly oxidized by H2O2 with a residue of H2O2 persisting in cloud water after SO2 has been converted. Changes in the gas phase concentrations of SO2 and H2O2 are shown during a cloud event. Both gases drop to very low concentrations in cloud with H2O2 tending to recover after available SO2 has been oxidized. The meteorology for each event is presented to illustrate the role of atmospheric structure in the transporting of emitted material and in determining cloud water compositions. Finally, a cloud chemistry climatology for winter and summer is presented, based upon 6 years of observations at Whiteface Mountain.