Measurements of CO₂, its stable isotopes, O₂/N₂, and ²²²Rn at Bern, Switzerland

P. Sturm (1) , M. Leuenberger (1) , F. L. Valentino (1) , B. Lehmann (1) , B. Ihly (1)

1 CEP - Climate and Environmental Physics [Bern]

A one-year time series of continuous atmospheric CO₂ measurements from Bern, Switzerland is presented. O₂/N₂ and Ar/N₂ ratios as well as stable carbon and oxygen isotopes of CO₂ and ?²⁹N₂, ?³⁴O₂ and ?³⁶Ar were measured periodically in a continuous way during a one year period. Additionally, the ²²²Rn activity was measured during three months in the winter 2004. Using the correlation from short term fluctuations of CO₂ and ²²²Rn we estimated a mean CO₂ flux density between February 2004 and April 2004 in the region of Bern of 95±39 tC km^?2 month^?1. The continuous observations of carbon dioxide and associated tracers shed light on diurnal and seasonal patterns of the carbon cycle in an urban atmosphere. There is considerable variance in nighttime ?¹³C and ?¹⁸O of source CO₂ throughout the year, however, with generally lower values in winter compared to summertime. The O₂:CO₂ oxidation ratio during the nighttime build-up of CO₂ varies between ?0.96 and ?1.69 mol O₂/mol CO₂. Furthermore, Ar/N₂ measurements showed that artifacts like thermal fractionation at the air intake are relevant for high precision measurements of atmospheric O₂.

Domaines: Océan, Atmosphère

P. Sturm, M. Leuenberger, F. L. Valentino, B. Lehmann, B. Ihly. Measurements of CO₂, its stable isotopes, O₂/N₂, and ²²²Rn at Bern, Switzerland. Atmospheric Chemistry and Physics Discussions, 2005, 5 (5), pp.8473-8506. ⟨hal-00301761⟩