Open AccessDetailed analysis of the isotopic composition of CO and characterization of the air masses arriving at Mount Sonnblick (Austrian Alps)
Author(s) -
Gros Valérie,
Bräunlich Maya,
Röckmann T.,
Jöckel P.,
Bergamaschi P.,
Brenninkmeijer C. A. M.,
Rom W.,
Kutschera W.,
Kaiser A.,
Scheel H. E.,
Mandl M.,
Plicht J.,
Possnert G.
Publication year - 2001
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 - 10.1029/2000jd900509
Subject(s) - atmospheric sciences , troposphere , middle latitudes , environmental science , isotope , air mass (solar energy) , subtropics , stratosphere , isotope analysis , relative humidity , humidity , stable isotope ratio , chemical composition , geology , climatology , meteorology , chemistry , physics , oceanography , boundary layer , quantum mechanics , fishery , biology , thermodynamics , organic chemistry
Air sampling for analysis of CO and its isotopic composition ( 13 C, 18 O, and 14 C) has been performed at the alpine station Sonnblick (47°N, 13°E, 3106 m above sea level) since September 1996. A high degree of variability is observed, which is due to the wide variation in the origin of air masses sampled. On the basis of the CO and isotope results, a classification of the different samples is performed. Other data such as 7 Be, O 3 , relative humidity, and back trajectories are used to give additional information about the air mass origin. Background values, representative of the NH midlatitudes free troposphere, are observed about 50% of the time and are used to define seasonal cycles. CO and its isotopes show a minimum in summer and a maximum in winter with extreme values of 90 and 160 ppb for CO, −30 and −25‰ for δ 13 C, 0 and 8‰ for δ 18 O, and 8 and 20 molecules cm −3 STP for 14 CO. CO and stable isotope data are compared with results from a three‐dimensional model (TM2). Generally good agreement supports the CO, δ 13 CO, and δC 18 O source/sink distributions inferred by the model. According to model calculations, fossil fuel combustion contributes 35% in summer and 50% in winter of total CO for such a midlatitude location. Other categories of sampled air are “subtropical,” “polluted,” and “stratospheric” and are observed 24%, 18%, and 4% of the time. Corresponding signatures of CO and its isotopic variations are presented, and some specific events are discussed.