Deposition of atmospheric nitrous acid on alkaline snow surfaces

H. J. Beine (1) , A. Amoroso (1) , G. Esposito (1) , R. Sparapani (1) , A. Ianniello (1) , T. Georgiadis (2) , M. Nardino (2) , P. Bonasoni , P. Cristofanelli , Florent Domine (3)

1 CNR-IIA - Istituto sull’Inquinamento Atmosferico
2 IBIMET - Istituto di Biometeorologia [Bologna]
3 LGGE - Laboratoire de glaciologie et géophysique de l'environnement

The photolysis of atmospheric nitrous acid (HONO) is a significant source of OH radicals in remote and Polar Regions. HONO is produced in/on snow surfaces in a photochemical reaction from nitrate ions. In an attempt to quantify the production of HONO at a snow covered mid-latitude location we made measurements of HONO fluxes for a 10-day period at the Mt. Cimone (MTC) research station in the Italian northern Apennines (2165 m asl) during March 2004. Production fluxes under normal background conditions were small, and reached maximum values of 20 nmol m−2 h−1 on only two occasions. However, during a transport event of Saharan dust to MTC we observed deposition fluxes of up to −120 nmol m−2 h−1 of HONO on to the snow surface. The deposited Sahara dust had rendered the surface snow alkaline, so that large amounts of acids could be absorbed from the atmosphere.

Keywords: Global Change: Atmosphere; Atmospheric Composition and Structure: Instruments and techniques; Atmospheric Composition and Structure: Troposphere: composition and chemistry; Atmospheric Composition and Structure: Troposphere: constituent transport and chemistry

Domains: Ocean, Atmosphere

H. J. Beine, A. Amoroso, G. Esposito, R. Sparapani, A. Ianniello, et al.. Deposition of atmospheric nitrous acid on alkaline snow surfaces. Geophysical Research Letters, 2005, 32 (L10808), 1 à 4 p. ⟨10.1029/2005GL022589⟩. ⟨insu-00373750⟩