loac (light optical aerosol counter) · loac (light optical aerosol counter): a new small...
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LOAC (Light Optical Aerosol Counter): a new small balloon-borne aerosol counter/sizer with
some particle characterization capabilities
J.-B. Renard, G. Berthet, F. Jegou, M. JeannotLPC2E-CNRS, Orléans, France
F. Dulac, J. Sciare, J. NicolasLSCE/CEA, Gif-sur-Yvette, France
M. Mallet, P. DurandLA, Toulouse, France
C. Thaury, S. Salles, J.-L. Mineau, T. TonnelierEnvironnement-SA company, Poissy, France
N. VerdierCNES, Toulouse, France
P. CharpentierMeteoMODEM company, Ury, France
J. GiacomoniAerophile SA company
H. OlafssonIceland University
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Different types of aerosols in the troposphere and the stratosphere, having different origins
Interplanetary grains
Pollution
Volcanoes
Transported sands
Disintegrated meteorites
Biomass burning (and pyroconvection)
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How to study aerosols when not at ground?From satellites (remote sensing of the atmosphere)- Estimation of aerosols size and nature (using some hypothesis
for the data analysis)
Aerosols
Lidar measurements from Calipso
Extinction from GOMOS/envisat
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From dedicated aircrafts and from (large) balloons: - Collecting techniques, optical instruments
Aerosol counter STAC operated in the middle atmosphere, below stratospheric balloons
Vertical profiles and size distribution … assuming liquid particles (which is not always the case even in the stratosphere)
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Only sparse in situ measurements and strong constraints: - High costs (aircrafts and balloons)- Technical limitations (how to fly during strong volcanic eruption?)- Need of complex infrastructures (few launching bases in the world for the stratospheric balloons)
There is a need for an aerosol counter that can be launched under all kinds of balloons (including meteo balloons) :- Low cost (the instrument can be lost after the flight)- Light instrument- Insensitive to the aerosols nature (accurate determination of size), which is not the case with the usual aerosol counters.
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LOAC : Light Optical Aerosol Counter
Measurements at 2 scattering angles :12°, where the scattered light is ~ insensitive to the nature of the aerosols60°, where the scattered light is very sensitive to the nature of the aerosols
Combining the measurements=> accurate determination of the size distribution=> estimation of the main nature of the aerosols
Aerosols Laser
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Collaboration between French research institutes and private companies
LOAC was design and tested in our institutes (CNRS and CNES)LOAC is build by Environnement-SA companyGondola and telemetry are build by MeteoMODEM company
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- 20 size classes between 0.4 - 100 μm
- - Optical chamber and pump: weight < 500 g
- Can work during 4 hours with 2 alkaline batteries of 4.5 V
-Total weigh with gondola for flight under meteo balloon : 1 kg (using meteoMODEM telemetry)
Large stratospheric balloon
Long duration stratospheric balloon
Meteo balloon
Low altitude troposheric balloon
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First version of LOAC (10 copies 2011-2012): 3 flights under large stratospheric balloons (Sweden and Brazil)6 flights under meteo balloons (Iceland, France)9 months onboard a tethered balloon (Touristic balloon “Air de Paris”)
4 LOAC are lost …
Improved version of LOAC (20 copies at the end of 2012)2 test flights under meteo balloon at the end of August 2012 (France)
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Kiruna, Northern Sweden, 1 April 2011 (large stratospheric balloon, onboard German gondola TWIN, CNES launch)
Strong variability of aerosol content
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West Iceland, 20 July 2011 (meteo balloon, Iceland meteo office launch)
“clean stratosphere”
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Comparison of the 2 measurements channels at scattering angles of 12° and 60° (size distributions)
=> identification of the main nature of the aerosols (by comparison to a laboratory data base)
The 2 curves are close => liquid aerosols
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Bauru (Brazil), 13 March 2012 (stratospheric balloon, Reims University “Tropico project”)
Several enhancements of “large” particles around 10 μmSoot particles ?
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Sausset-les-Pins (France), 28 June 2012 (meteo balloon, CNES)
2 flights during an episode of sand above Mediterranean sea
Size grains in the 5-30 μm range
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At ground, liquid aerosols (launch on the beach)
On the middle troposphere, sand
DataCarbonMineralDroplets
DataCarbonMineralDroplets
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LOAC is involved in several projects:
Mid-september 2012 : tests of the new version of LOAC during sand events, meteo balloon (Meteo France)
Winter 2012-2013: ParisFog campaign, study of fog, tethered balloon (SIRTA – meteo France)
Beginning of 2013: Tests onboard low altitude tropospheric balloons “BPCL” (CNES)
Summer 2013: Charmex campaign, study of aerosols transport above Mediterranean sea, BPCL and meteo ballons (CNES)
End of 2013: Aerowave campaign, stratospheric aerosols, large stratospheric balloons (CNES)
…
2018 : Strateole phase 2, tens of long-duration stratospheric balloons above equatorial regions