Long-term measurements of atmospheric key species
at the GAW global station Hohenpeissenberg
W. Thomas, B. Briel, A. Claude, T. Elste, J. Englert, H. Flentje, R. Holla, D. Kubistin, M. Lindauer, J. Müller, M. Schumacher and
C. Plass-Dülmer
Since 1995 measurements of atmospheric key species are routinely taken
at the GAW station Zugspitze/Hohenpeissenberg within the Global
Atmosphere Watch (GAW) programme of WMO. At the Hohenpeissenberg
site we focus on short-lived reactive gases and aerosol parameters
whereas long-lived climate forcers are primarily measured at the site
Schneefernerhaus. Main components of the measurement programme are
ozone, carbon monoxide, sulphur dioxide, nitrogen oxides (NOx and NOy),
PAN, OH/H2SO4, about 120 VOCs and since 2012 also methane and
carbon dioxide contributed by the Integrated Carbon Observing System
(ICOS) project. Filter measurements and wet chemical analysis provide
the chemical composition of water-soluble aerosols and of rain probes,
further complemented by measurements of an Aerosol Chemical
Speciation Monitor (ACSM). Aerosol parameters are particle number,
particle mass, soot mass, size distribution, scattering and absorption
coefficients, spectral AOD measurements, and extinction and backscatter
profiles from a multi-channel Raman Lidar and a ceilometer, respectively.
Fig. 1: The Hohenpeissenberg observatory on May 9th 2016 viewed from South
Site description
Hohenpeissenberg is an isolated mountain station in a rural environment in about 985 m a.s.l. 65 km southwest of Munich in the Alpine foreland. The surrounding landscape
250 m below the observatory is dominated by meadows, forests and villages without major industrial production sites. Local anthropogenic emissions are mostly due to traffic
and domestic heating but also agricultural activities, e.g. manuring in spring-time, forest fires and biomass burning during wintertime. The summit of Hoher Peissenberg is
often higher than the wintering mixing layer height, thus allowing measurements in the free troposphere during such periods. Measurements of meteorological parameters
started already back in 1781 and the observatory holds the world longest temperature time series of a mountain station.
Fig. 2: Annual average mass concentration of total
suspended matter (TSP, blue), and soot (black) from
1995 to 2015. The linear decreasing trends (dashed
lines) of both parameters are statistically significant.
Fig. 3: Annual average values of 10×NO (yellow), NO2
(orange), NOy (brown) and O3 (red) mixing ratios from
1995 to 2015. NO and NO2 levels seem to decrease
after a maximum in 2010 and O3 seems to decrease
after 2004/2005 whereas NOy does not show a trend.
Fig. 4: Annual average values of carbon monoxide (blue)
and sulphur dioxide (orange) mixing ratios from 1995
to 2015. The linear decreasing trends (dashed lines) of
both parameters are statistically significant.
Fig. 5: Yearly cycles of selected VOCs mainly originating from anthropogenic activities from 1998-2015. Most organic Fig. 6: Average results of two years of aerosol mass
spectrometry (2014, 2015) of particles < 1 μm taken by
species show a slightly decreasing tendency which corresponds to results of inorganic species and aerosols.
an Aerosol Chemical Speciation Monitor (ACSM).
Results
Total suspended matter and soot concentration both significantly decrease within past 18 years (Fig. 2), which is plausibly a consequence of national and European legislative
efforts to reduce atmospheric pollutants. The results are mostly in line with nitrogen components NO and NO 2 for the same period whereas NOy does not show any trend
(Fig. 3) from 1998 to 2012. The ozone amount seems to slightly decrease after 2004/2005. Carbon monoxide and sulphur dioxide mixing ratios both decrease statistically
significant with time (Fig. 4). Yearly cycles of VOCs reveal decreasing mixing ratios between 1998 and 2015 (Fig. 5). Fig. 6 finally shows the main chemical components of
particles (average of years 2014/2015) at the rural site Hohenpeissenberg, which are organic matter (OM) and nitrate, followed by sulphate and ammonium.
Deutscher Wetterdienst, Meteorologisches Observatorium Hohenpeißenberg
[email protected]