Showing papers by "Ulrich Platt published in 1984"
TL;DR: Experimental field data support the earlier hypothesis that this loss process of NO/ sub 3/ may constitute both a major sink for atmospheric NO/sub x/ and a significant formation route for nitric acid, a key component of acid rain and fog.
Abstract: Nighttime profiles of the atmospheric concentrations of the nitrate radical (NO/sub 3/), NO/sub 2/, and O/sub 3/ have been obtained by using a mobile differential ultraviolet/visible absorption spectrometer over path lengths from 3 to 17 km. Measurements were carried out at four semiarid/desert sites in the southern California desert (Death Valley, Edwards Air Force Base, Phelan, and Whitewater), and nitrate radicals were observed at all four locations at typical concentrations of approx. 10-100 parts per trillion. A decrease in the calculated NO/sub 3/ lifetime with increasing relative humidity (RH) was observed with lifetimes up to approx. 60 min for less than or equal to50% RH, but less than or equal to10 min for greater than or equal to50% RH. This suggests the involvement of water in the loss process for NO/sub 3/, either in the gas phase or in the aqueous state at the ground or on aerosol surfaces. These experimental field data support our earlier hypothesis that this loss process of NO/sub 3/ may constitute both a major sink for atmospheric NO/sub x/ and a significant formation route for nitric acid, a key component of acid rain and fog.
230 citations