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| Titel |
Measuring the vertical distributions of the upper tropospheric and stratospheric dust with a LOAC aerosol counter under meteorological balloons |
| VerfasserIn |
Damien Vignelles, Jean-Baptiste Renard, Gwenaël Berthet, François Dulac, Benoît Couté, Matthieu Jeannot, Fabrice Jegou, Haraldur Ólafsson, Pavla Dagsson Waldhauserova |
| 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 |
250091498
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| Publikation (Nr.) |
 EGU/EGU2014-5797.pdf |
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| Zusammenfassung |
| The aerosol issue is in a constant growing. At ground, the airborne particles in boundary layer
represent a real risk for population and must be control. In the middle troposphere, aerosols
play an important role in the microphysics and meteorology, the heterogeneous chemistry is
not well understood. In the stratosphere, several teams of researchers have shown that solid
aerosols might exist, the question of the dynamic of these solid aerosol in the stratosphere is
open.
The aim was to develop an instrument that it can make measurements from the ground to
the middle stratosphere. This instrument must be able to be put under meteorological
balloons, which represent the worst conditions for the development of such instruments in
terms of weight, resistance under large variations of temperature and pressure, autonomy and
cost if we consider that something throw under a meteorological balloon can be lost after the
fly. In the consideration of these conditions, we have developed a new instrument able to
make such kind of measurements. This instrument is call LOAC for Light Optical Aerosol
Counter.
LOAC provides the concentration and size distribution of aerosols on 19 channels from
0.2 μm to 50.0 μm every ten seconds, and determine the main nature of particles
(carbonaceous aerosol, mineral, droplets of water or sulfuric acid) in relation with a large
range of samples in laboratory. The physical technique is based on the observation of the
scattered light by particles at two angles. LOAC is light enough (1 kilogram) to be placed
under a meteorological balloon that is very easy to launch such balloons. The goal is to
perform a large number of flights to gather information about the dust distribution in
stratosphere and to understand the various mechanisms controlling their spatial and temporal
variability.
About 25 flights with have been performed in the stratosphere with the LOAC above the
Mediterranean Sea, from south of Paris, from Aire-Sur-l’Adour (South-West of France) and
form Iceland. For this period of observation, the stratosphere is characterized by a
“background” aerosol content, i.e. free of any volcanic influence. In this context, we show
that both liquid and solid particles are present, depending on the altitude and on the aerosol
sizes. A series of one year of flight will be presented to highlight the trend in the aerosol
content. Also, the analysis of individual profiles exhibits a strong variability in terms of
concentration and composition both in the upper troposphere and in the stratosphere.
Such variations are often linked with the aerosol composition. The reasons of such
variability are investigated, in particular in terms of air mass origins and transport. |
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