Title: Possible contribution of N<sub>2</sub>O<sub>5</sub> scavenging to HNO<sub>3</sub> observed in winter stratiform cloud
Abstract: During a winter field study in early 1984, the concentrations of NO 3 − , SO 4 = , and H + , measured in cloud water samples collected in the bases of deep stratiform clouds and in the aerosol and gas phases below cloud, suggested a substantial enhancement of NO 3 − in the cloud water samples for 8 of 12 days. For these 8 days, variations in cloud water NO 3 − /SO 4 = were associated with an excess H + /SO 4 = in the cloud water, indicating HNO 3 . For the conditions of study, which included subfreezing temperatures and weak solar fluxes to the low‐level cloud, the possibility exists that much of the NO 3 − in the cloud water was from the formation and subsequent scavenging of N 2 O 5 by cloud droplets. A chemical model set in a Lagrangian framework is used to describe the daytime evolution of odd nitrogen species, including dry deposition of HNO 3 , under conditions approximating the average conditions for the 8 days. Computations with no cloud scavenging of N 2 O 5 predict an average cloud water NO 3 − mixing ratio well below the geometric mean determined for the measurements. For the conditions most typical of the observations, the production rate of HNO 3 via the cloud scavenging of N 2 O 5 was computed to be approximately equal to that for the gas‐phase production of HNO 3 .
Publication Year: 1988
Publication Date: 1988-10-20
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 17
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