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

摘要

A one-year time series of atmospheric CO measurements fromBern, Switzerland, is presented. O/N and Ar/N ratiosas well as stable carbon and oxygen isotopes of CO andδN, δO and δAr weremeasured periodically during a one year period. Additionally, theRn activity was measured during three months in the winter2004. Using the correlation from short-term fluctuations of COand Rn we estimated a mean CO flux density betweenFebruary 2004 and April 2004 in the region of Bern of95±39 tC kmmonth. The continuousobservations of carbon dioxide and associated tracers shed lighton diurnal and seasonal patterns of the carbon cycle in an urbanatmosphere. There is considerable variance in nighttimeδC and δO of source CO throughout theyear, however, with generally lower values in winter compared tosummertime. The O:CO oxidation ratio during the nighttimebuild-up of CO varies between –0.96 and–1.69 mol O/mol CO. Furthermore, Ar/Nmeasurements showed that artifacts like thermal fractionation atthe air intake are relevant for high precision measurements ofatmospheric O.