Direct measurement of NO3 radical reactivity in a boreal forest

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Liebmann , J , Karu , E , Sobanski , N , Schuladen , J , Ehn , M , Schallhart , S , Quelever , L , Hellen , H , Hakola , H , Hoffmann , T , Williams , J , Fischer , H , Lelieveld , J & Crowley , J N 2018 , ' Direct measurement of NO3 radical reactivity in a boreal forest ' , Atmospheric Chemistry and Physics , vol. 18 , no. 5 , pp. 3799-3815 . https://doi.org/10.5194/acp-18-3799-2018

Title: Direct measurement of NO3 radical reactivity in a boreal forest
Author: Liebmann, Jonathan; Karu, Einar; Sobanski, Nicolas; Schuladen, Jan; Ehn, Mikael; Schallhart, Simon; Quelever, Lauriane; Hellen, Heidi; Hakola, Hannele; Hoffmann, Thorsten; Williams, Jonathan; Fischer, Horst; Lelieveld, Jos; Crowley, John N.
Contributor organization: Department of Physics
Polar and arctic atmospheric research (PANDA)
Date: 2018-03-15
Language: eng
Number of pages: 17
Belongs to series: Atmospheric Chemistry and Physics
ISSN: 1680-7316
DOI: https://doi.org/10.5194/acp-18-3799-2018
URI: http://hdl.handle.net/10138/233974
Abstract: We present the first direct measurements of NO3 reactivity (or inverse lifetime, s(-1))in the Finnish boreal forest. The data were obtained during the IBAIRN campaign (Influence of Biosphere-Atmosphere Interactions on the Reactive Nitrogen budget) which took place in Hyytiala, Finland during the summer/autumn transition in September 2016. The NO3 reactivity was generally very high with a maximum value of 0.94 s(-1) and displayed a strong diel variation with a campaign-averaged nighttime mean value of 0.11 s(-1) compared to a daytime value of 0.04 s(-1). The highest nighttime NO3 reactivity was accompanied by major depletion of canopy level ozone and was associated with strong temperature inversions and high levels of monoterpenes. The daytime reactivity was sufficiently large that reactions of NO3 with organic trace gases could compete with photolysis and reaction with NO. There was no significant reduction in the measured NO3 reactivity between the beginning and end of the campaign, indicating that any seasonal reduction in canopy emissions of reactive biogenic trace gases was offset by emissions from the forest floor. Observations of biogenic hydrocarbons (BVOCs) suggested a dominant role for monoterpenes in determining the NO3 reactivity. Reactivity not accounted for by in situ measurement of NO and BVOCs was variable across the diel cycle with, on average, approximate to 30% "missing" during nighttime and approximate to 60% missing during the day. Measurement of the NO3 reactivity at various heights (8.5 to 25 m) both above and below the canopy, revealed a strong nighttime, vertical gradient with maximum values closest to the ground. The gradient disappeared during the daytime due to efficient vertical mixing.
Subject: VOLATILE ORGANIC-COMPOUNDS
NOCTURNAL BOUNDARY-LAYER
IN-SITU MEASUREMENTS
RURAL MOUNTAIN-SITE
SCOTS PINE
OXIDATION CAPACITY
SEASONAL-VARIATION
SESQUITERPENE EMISSIONS
ATMOSPHERIC CHEMISTRY
BIOGENIC EMISSIONS
114 Physical sciences
1172 Environmental sciences
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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