In-situ measurements of oxygen, carbon monoxide and greenhouse gases from Ochsenkopf tall tower in Germany

Abstract

In addition to the in-situ measurements, flask samples are taken at Ochsenkopf at approximately weekly intervals and are subsequently analysed for the mixing ratios of the same species, as well as H 2 , and the stable isotopes, δ 13 C, δ 18 O in CO 2 . The in-situ measurements of CO 2 and O 2 from 23 m show substantial diurnal variations that are modulated by biospheric fluxes, combustion of fossil fuels, and by diurnal changes in the planetary boundary layer height. Measurements from 163 m exhibit only very weak diurnal variability, as this height (1185 m a.s.l.) is generally above the nocturnal boundary layer. CH 4 , CO, N 2 O and SF 6 show little diurnal variation even at 23 m owing to the absence of any significant diurnal change in the fluxes and the absence of any strong local sources or sinks. From the in-situ record, the seasonal cycles of the gas species have been characterized and the multi-annual trends determined. Because the record is short, the calculation of the trend is sensitive to inter-annual variations in the amplitudes of the seasonal cycles. However, for CH 4 a significant change in the growth-rate was detected

Continuous CO<sub>2</sub>/CH<sub>4</sub>/CO measurements (2012–2014) at Beromünster tall tower station in Switzerland

“…The timing of the maximum of the seasonal variation is similar to CO 2 , and the mean peak-topeak amplitude of CO is 47.7 ppb averaged over the 2 years. Other tall tower stations in Europe reported much higher seasonal amplitudes between 75 and 130 ppb (Thompson et al, 2009;Vermeulen et al, 2011;Popa et al, 2010). Similar to CO 2 , some of the differences in the observed seasonal amplitudes might be related to data selection, and taking the daily means from the inter-quartile (25-75 %) range results in higher mean peak-to-peak amplitude of 54.5 ppb over the 2 years.…”

“…Therefore, seasonal amplitudes for CH 4 were not calculated. In contrast to Beromünster, other tall tower stations in Europe (Thompson et al, 2009;Popa et al, 2010;Schmidt et al, 2014;Vermeulen et al, 2011) have reported more pronounced seasonal amplitudes between 35 and 70 ppb.…”

“…The seasonal variations of CO 2 are associated with biological activity; the minimum occurs in August and the maximum in March, as expected for a Northern Hemisphere site (Randerson et al, 1997). The observed amplitude can be compared with other tall tower stations in Europe: for Cabauw in the Netherlands (Vermeulen et al, 2011), Bialystok in Poland (Popa et al, 2010), and Ochsenkopf in Germany (Thompson et al, 2009), the observed seasonal amplitudes were 25, 20 and 15.5 ppm, respectively. The observed seasonal variation at Beromünster is comparatively low, but this may partly be explained by the filtering of the data.…”

“…The first tall tower atmospheric measurements launched in the United States in the early 1990s (Bakwin et al, 1995(Bakwin et al, , 1998 were followed by atmospheric tall towers in Europe and Asia (Popa et al, 2010;Winderlich et al, 2010;Thompson et al, 2009;Schmidt et al, 2014;Vermeulen et al, 2011). In the early 21st century, a European network of tall tower stations was established under the umbrella of the CHIOTTO (Continuous High Precision Tall Tower Observations of Greenhouse Gases, www.…”

Continuous measurements of greenhouse gases and atmospheric oxygen at the Namib Desert Atmospheric Observatory

“…The DFCA measures the O 2 mole fraction directly in dry air through an electrochemical method (Thompson et al, 2007(Thompson et al, , 2009Stephens et al, 2007). There are two sensors in the device, each containing an anode, cathode, and weak acid electrolyte.…”