Ozone, carbon monoxide and nitrogen oxides time series at four alpine GAW mountain stations in central Europe

Abstract

Abstract. Long-term, ground based in-situ observations of ozone (O 3 ) and its precursor gases nitrogen dioxide (NO 2 ) and carbon monoxide (CO) from the four sites Hohenpeissenberg and Zugspitze (D), Sonnblick (A) and Jungfraujoch (CH) are presented for the period 1995-2007. These Central European alpine mountain observatories cover an altitude range of roughly 1000 to 3500 m. Comparable analytical methods and common quality assurance (QA) procedures are used at all sites. For O 3 and CO, calibration is linked to primary calibrations (O 3 ) or CO standards provided by the Central Calibration Laboratory (CCL) at NOAA/ESRL. All stations have been audited by the World Calibration Centre (WCC) for CO and O 3 (WCC-Empa; CH). Data from long-term measurements of NO 2 and CO are only available from Hohenpeissenberg and Jungfraujoch. Both sites show slightly decreasing mixing ratios of the primarily emitted NO 2 and the partly anthropogenically emitted CO between 1995 and 2007. The findings are generally consistent with shorter observation periods at Zugspitze and Sonnblick and thus are considered to represent regional changes in Central European atmospheric composition at this altitude range. Over the same period, 1995-2007, the O 3 mixing ratios have slightly increased at three of the four sites independent of wind sector. Trends are often more pronounced in winter and less in summer; highest declines of NO 2 and CO are observed in winter and the lowest in summer, whereas the strongest O 3 increase was detected in winter and lowest or even decline in summer, respectively. Weekly cycles demonstrate anthropogenic impact at all elevations with enhanced NO 2 on working days compared to weekends. Enhanced O 3 Correspondence to: S. Gilge (stefan.gilge@dwd.de) values on working days indicating photochemical production from anthropogenic precursors are only observed in summer, whereas in all other seasons anti-correlation with NO 2 was found due to reduced O 3 values on working days. Trends are discussed with respect to anthropogenic impacts and vertical mixing. The observed trends for NO 2 at the alpine mountain sites are less pronounced than trends estimated based on emission inventories.

1997–2007 CO trend at the high Alpine site Jungfraujoch: a comparison between NDIR surface in situ and FTIR remote sensing observations

“…Since the European emissions declined significantly during the considered years (see Fig. 13), the negative in situ CO trends at JFJ are indeed more pronounced for south-easterly (−2.0 % year −1 ) than for northwesterly advection (−1.6 % year −1 ) (Gilge et al, 2010).…”

“…Such events are capable of transporting polluted air masses from the highly industrialized Po Basin in Northern Italy to the Jungfraujoch . Indeed, in situ CO concentrations at JFJ are on average highest during south-easterly advection (Gilge et al, 2010). Other meteorological situations associated with elevated CO, are synoptic lifting and thermally-induced vertical transport (Zellweger et al, 2003).…”

“…The trend for the in situ measurements agrees well with the observed CO trend at the Zugspitze summit (2962 m a.s.l. in the German Alps) of −3.16 ± 0.4 ppb year −1 for the 1995 to 2002 period (Gilge et al, 2010). Next we will explore possible reasons for the trend difference observed at JFJ.…”

Lower tropospheric ozone at northern midlatitudes: Changing seasonal cycle

“…These data sets include four European records: two from alpine sites (Zugspitze, Germany and Jungfraujoch, Switzerland), a lower elevation, midcontinental site (Hohenpeissenberg, Germany) and a marine boundary layer site (Mace Head, Ireland). The European data were provided by coauthors of this paper; the German and Swiss data are as described by Gilge et al [2010]. The Jungfraujoch and Hohenpeissenberg data are also available from the World Data Centre for Greenhouse Gases at http://ds.data.jma.go.jp/gmd/wdcgg/.…”

Measurement of Ozone Concentration on the Elevation Gradient of a Low Hill by a Semiconductor-Based Portable Monitor

“…The observed decline of mountain forests and the increasing trend of tropospheric ozone in the Northern Hemisphere [4] have prompted the installation of monitoring stations of ozone and other relevant species in high-elevation mountains [5][6][7][8]. Such stations have revealed various aspects of the vertical structure of ozone concentration, and we have a fairly good understanding of the broad-scale behaviors of tropospheric ozone.…”