Open AccessThe nitrate radical in the remote marine boundary layer
Author(s) -
Allan Beverley J.,
McFiggans Gordon,
Plane John M. C.,
Coe Hugh,
McFadyen Gordon G.
Publication year - 2000
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2000jd900314
Subject(s) - environmental science , nitrate , differential optical absorption spectroscopy , sink (geography) , boundary layer , atmospheric sciences , nox , air mass (solar energy) , oceanography , environmental chemistry , absorption (acoustics) , chemistry , geology , materials science , combustion , physics , cartography , organic chemistry , composite material , thermodynamics , geography
The technique of differential optical absorption spectroscopy has been used to determine the nitrate radical (NO 3 ) concentration in the remote marine boundary layer. The instrument was deployed in campaigns at Mace Head on the west coast of Ireland and on the north coast of Tenerife. A comprehensive set of NO 3 measurements under a wide variety of conditions was obtained. For instance, nighttime NO 3 levels at Mace Head ranged from 1 to 5 ppt in the clean marine atmosphere and from 1 to 40 ppt in semipolluted continental air masses. The nightly averaged NO 3 lifetime varied from less than 2 min to 4 hours. At Tenerife, where there was less variability in conditions, nighttime NO 3 ranged from 1 to 20 ppt, with nightly averaged lifetimes between 4 and 34 min. A photochemical box model, fully constrained by measurements of species that control the formation and removal of NO 3 , was then employed to determine the major loss mechanisms of the radical. This shows that NO 3 in the clean marine air masses is very sensitive to small increases in the concentrations of dimethyl sulphide (DMS) and nonmethane hydrocarbons and that the radical is rarely in chemical steady state. At Tenerife, 80–90% of NO 3 was removed by reaction with DMS. However, in continental air masses with little marine influence, indirect losses of NO 3 via dinitrogen pentoxide (N 2 O 5 ) usually dominate. It appears that in much of the North Atlantic, NO 3 is a more efficient sink for DMS compared to the hydroxyl radical (OH) during the day.