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| Titel |
Continuous CO2/CH4 measurement at Zotino Tall Tower Observatory (ZOTTO) in Central Siberia |
| VerfasserIn |
Jan Winderlich, Huilin Chen, Annette Höfer, Christoph Gerbig, Alexey Panov, Martin Heimann |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035887
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| Zusammenfassung |
| Global climate change has particular impact on Siberia, where one tenth of global vegetation
and soil carbon is stored. The increase in temperature lengthens the vegetation period
and consequently enlarges the carbon sink. On the other hand, a warming climate
will enhance thawing of permafrost which contains organic carbon that can be
released either as carbon dioxide or methane depending on the local hydrological
conditions.
Long-term biogeochemical trace gas measurements on tall towers (>Â 250Â m) over
continents help to improve the knowledge about surface source/sink processes at regional to
continental scales. Without the usage of aircrafts, the height of the tower allows regular
probing of the mixed part of the boundary layer, which is – unlike the surface layer – only
moderately influenced by diurnal variations of local surface fluxes and thus representative for
a larger region (~1000km). The recently established Zotino Tall Tower Observatory
(ZOTTO, 304Â m, www.zottoproject.org) is located near the village of Zotino at the Yenisei
River in central Siberia (60Ë N, 89Ë E). The ZOTTO facility was built in the perspective to
monitor and determine variability and trends in the carbon balance of central Siberian
forests.
Since April 2009 we measure CO2 and CH4 from 6 height levels reaching from 4 to
301Â m with an analyzer based on the cavity ring-down spectroscopy technique (Picarro Inc.,
CA, USA, model G1301). Experiments have shown that reliable accurate measurements can
be obtained even without drying the sample gas. To obtain dry air mixing ratios for CO2 and
CH4, the simultaneous water vapor measurements are used to correct dilution and pressure
broadening effects, resulting in a precision and accuracy that is better than WMO
recommendations. Furthermore, the system requires only a very low amount of
calibration gases, because calibration takes place only every 100Â hrs. These two aspects
allow keeping maintenance low, which is an important requirement for this remote
station.
In each sampling line buffer volumes integrate the atmospheric signal over a typical time
period of 40 minutes. With these the periodic switching from line to line every three minutes
with only one single analyzer provides a quasi continuous, concurrent measurement from
each height level. As a consequence of the averaging as well as the precision of
the analyzer, the data show a low noise level and still moderately high temporal
resolution, and gradients between different levels can be determined to a very high
accuracy.
The new data from 2009 and 2010 will be presented and interpreted in the context of
regional sources and sinks of CO2 and CH4 in central Siberia. As the nocturnal boundary
develops during night, it locally traps respired CO2 and CH4 and builds up vertical gradients.
The analysis of the gradients allows estimating the trapped carbon amount in this layer which
can be assigned to a certain region by using the Lagrangian transport model STILT. |
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