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| Titel |
Observations of RHS concentrations and processes at the Dead Sea Valley |
| VerfasserIn |
Stefan Schmitt, Robert Holla, Katharina Kamilli, Jutta Zingler, Udo Frieß, Andreas Held, Ulrich Corsmeier, Ulrich Platt |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092875
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| Publikation (Nr.) |
 EGU/EGU2014-7238.pdf |
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| Zusammenfassung |
| The gas phase halogen chemistry in the lower troposphere is known to play an important role
in the chemistry of the Earth’s atmosphere. Due to their high reactivity, halogens, even in
small mixing ratios in the parts per trillion (ppt) range, can have a strong impact on the
chemical and physical composition of the enclosing air masses, e.g. fast ozone depletion or
particle formation. Due to the high reactivity the measurements are difficult, but can
reliable be made with Long Path Differential Optical Absorption Spectroscopy
(LP-DOAS).
The Dead Sea Valley (DSV), located at the border of Israel and Jordan, is a unique place
with high activity of reactive halogen species (RHS). Former DOAS measurements revealed
high abundances of bromine monoxide (BrO) as well as iodine monoxide (IO)
but the processes and sources are still not understood. Therefore we performed
intensive LP-DOAS measurements in May 2012. The measurement path of about
10 km was positioned entirely over the water surface of an evaporation pond in
the southern basin of the Dead Sea. We observed simultaneous diurnal cycles of
anthropogenic emitted trace gases like NO2, CH2O and SO2, and also RHS like
BrO, IO and I2. We observed mixing ratios of up to 90 ppt, 5ppt and 60 ppt for
BrO, IO and I2 respectively. NO2 mixing ratios dropped from about ppb to below
the detection limit of 0,5 ppb during sunrise on every day while significant BrO
and IO concentrations were only detected at low NO2 mixing ratios. This supports
the assumption that NO2 is consumed by the formation of BrONO2 and IONO2
from released RHS. The data shows several interesting chemical features which are
presented.
Further, condensation particle counter (CPC) measurements of particles with sizes of
9-800 nm indicate that significant mixing ratios of IO were observed only at low particle
loads while BrO seems to prefer high particle concentrations. This indicates a possible impact
of aerosols on the halogen chemistry at the DSV. |
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