A trace-gas climatology above Zotino, central Siberia

Abstract

Using light aircraft and at intervals of approximately 14 days, vertical profiles of temperature, humidity, CO 2 concentration and 13 C/ 12 C and 18 O/ 16 O ratio, as well as concentrations of CH 4 , CO, H 2 and N 2 O, from about 80 to 3000 m above ground level have been determined for the atmosphere above a flux measurement tower located near the village of Zotino in central Siberia (60 • 45 N, 89 • 23 E). As well as being determined from flask measurements (typically at heights of 100, 500, 1000, 1500, 2000, 2500 and 3000 m) continuous CO 2 concentration profiles at 1 Hz have also been obtained using an infrared gas analyser. This measurement program is ongoing and has been in existence since July 1998. Data to November 2000 are presented and show a seasonal cycle for CO 2 concentration of about 25 µmol mol −1 within the atmospheric boundary layer (ABL) and about 15 µmol mol −1 in the free troposphere. Marked seasonal cycles in the isotopic compositions of CO 2 are also observed, with that of oxygen-18 in CO 2 being unusual: always being depleted in the ABL with respect to the free troposphere above. This is irrespective of whether the CO 2 concentration is higher or lower in the free troposphere. We interpret this as indicating a net negative discrimination being associated with the net terrestrial carbon exchange, irrespective of whether photosynthesis or respiration dominates the net carbon flux in this region. During winter flights, large fluctuations in CO 2 concentration with height are often observed both within and above the stable ABL. Usually (but not always) these variations in CO 2 concentrations are associated with more or less stoichiometrically constant variations in CO and CH 4 concentrations. We interpret this as reflecting the frequent transport of polluted air from Europe with very little vertical mixing having occurred, despite the large horizontal distances traversed. This notion is supported by back-trajectory analyses. Vertical profiles of CO 2 concentration with supplementary flask measurements allow more information on the structure and composition of an air mass to be obtained than is the case for flask measurements or for ground-based measurements only. In particular, our data question the notion that there is usually anything like "well mixed background air" in the mid-to-high northern latitudes during the winter months.

Atmospheric CO2 in situ measurements: Two examples of Crown Design flights in NE Spain

“…In addition, the two stable layers identified in the lower troposphere (625 m and 1025-1200 m) mark a stepwise vertical distribution of the CO 2 concentration. As pointed by Lloyd et al [2002], under stable atmospheric conditions, the vertical mixing is strongly suppressed. This is in accordance by the observed layered CO 2 mixing rations below 1500 masl.…”

Isoprene and monoterpene fluxes from Central Amazonian rainforest inferred from tower-based and airborne measurements, and implications on the atmospheric chemistry and the local carbon budget

“…These were used as a third backup system specifically for isoprene determination. CO 2 and H 2 O mixing ratios were measured by an infrared gas analyzer (Licor 6261) setup according to Lloyd et al (2002). After take-off, ambient air from outside of the aircraft was continuously drawn through a ca.…”

Carbon Dioxide in the Free Troposphere and Boundary Layer at the Mt. Bachelor Observatory

“…As observed by others before, minimum CO 2 mixing ratios for both BL and FT averages occur each year during either summer or fall when there is the most drawdown of CO 2 by vegetation near the surface, while maximum CO 2 mixing ratios occur during early spring due to a buildup of CO 2 (via respiration, fuel burning, etc.) (Keeling et al, 1976;Thoning et al, 1989;Tans et al, 1990;Lloyd et al, 2002;Gurk et al, 2008;Ramonet et al, 2010;Shashkov et al, 2011;Brooks et al, 2012;Haszpra et al, 2012). For 2013 and 2014, the peak-to-peak amplitude of the CO 2 seasonal cycle (highest monthly mean -lowest monthly mean) at MBO is 8.07 and 8.45 ppmv, respectively.…”

“…Numerous types of sites have been used to measure atmospheric CO 2 , such as: surface observatories (Idso et al, 2001;Newman et al, 2008;Ramonet et al, 2010;Rice and Bostrom, 2011;Pérez et al, 2012), balloon soundings (Bischof et al, 1980;Li et al, 2014), aircraft measurements (Bischof et al, 1980;Lloyd et al, 2002;Machida et al, 2002;Sidorov et al, 2002;Gurk et al, 2008;Shashkov et al, 2011;Sun and De Wekker, 2011;Sweeney et al, 2015), tall towers (Bakwin et al, 1995;Haszpra et al, 2005;Haszpra et al, 2012), and mountain-top observatories (Goldman, 1974;Thoning et al, 1989;Sturm et al, 2005;De Wekker et al, 2009;Ramonet et al, 2010;Brooks et al, 2012). Even though there are numerous methodologies for the measurement of CO 2 and data on atmospheric CO 2 concentrations have been available since the late 1950s, atmospheric chemistry models still have difficulty estimating CO 2 concentrations in conditions other than in a well-mixed planetary boundary layer (Haszpra et al, 2012).…”