VOC measurements by PTR-ToF-MS at the Birkenes Observatory. A data summary report.

A high resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF- MS) was used for on-line and real-time measurements of volatile organic compounds (VOCs) at the Birkenes Observatory in Southern Norway. Measurements were carried out during late spring and summer 2012 and in January and early February 2013. Here we present the obtained PTRMS standard data product which includes volume mixing ratios of methanol, acetonitrile, acetaldehyde, acetone, dimethyl sulphide, isoprene, methacrolein plus methylvinylketone, methylethylketone, benzene, toluene, C8-alkylbenzenes, C9-alkylbenzenes and the sum of the monoterpene isomers. Exploratory data of formic acid, acetic acid, pinonaldehyde and three unidentified signals (m/z 87.080, m/z 89.060 and m/z 101.098) are also shown. PTR-ToF-MS mass spectra were dominated by oxygenated VOCs both in summer and in winter. Pure hydrocarbons were mostly aromatic hydrocarbons (benzene, toluene, C8-alkylbenzenes) in winter and biogenic hydrocarbons (monoterpenes and isoprene) in summer. The summertime data confirm that the Birkenes Observatory is an interesting site in the boreo-nemoral vegetation zone where it is possible to observe both monoterpene and isoprene emissions and their photochemical processing in the atmosphere.