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Abstract

As part of the EUROSIBERIAN CARBONFLUX project, regular measurements have been performed in the lower troposphere over a southern taiga forest area in Fyodorovskoye, Western Russia (56degrees28'N, 32degrees56'E). Up to 70 flights have been made between May 1998 and December 2000, plus additional intensive campaigns to study the diurnal variability of atmospheric trace gases within the boundary layer. We sampled flasks between 100 and 3000 m for analysis Of CO₂, delta(13)C and delta(18)O in CO₂, CH₄ and CO. In addition, in-situ CO₂, relative humidity, pressure and temperature were performed for a better description of the vertical variability and accurate determination of the boundary layer height. The peak-to-peak amplitude of the seasonal cycle of atmospheric CO₂ within the boundary layer of 26.5 ppm is about twice the one observed in the free troposphere (14.6 ppm). The spring draw down Of CO₂ also occurs one month earlier than in the free troposphere aloft. There is also an increase by factor of two in the vertical variability of CO₂ within the free troposphere between summer and winter, which may be related to the variability of advection and mixing. Linear regression analysis applied to flask measurements of CO, CH₄ and delta(13)C versus CO₂ in the free troposphere indicates that industrial emissions over Europe are a dominant source of synoptic variability in wintertime in air masses reaching Fyodorovskoye. On the other hand, the variability of trace gases in the boundary layer observed during intensive campaigns is consistent with the patterns of proximate sources over the underlying southern taiga landscape at Fyodorovskoye.