LOAC (Light Optical Particle Counter) a new aerosols counter for the determination of their sizes...
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Transcript of LOAC (Light Optical Particle Counter) a new aerosols counter for the determination of their sizes...
LOAC (Light Optical Particle Counter)a new aerosols counter for the determination of their
sizes and their main nature under meteorological balloons
P. CharpentierMeteoMODEM company, Ury, France
J.-B. Renard, G. Berthet, F. Jegou, M. JeannotLPC2E-CNRS, Orléans, France
F. DulacLSCE/CEA, Gif-sur-Yvette, France
M. MalletLA, Toulouse, France
C. Thaury, S. Salles, J.-L. Mineau, B. FournierEnvironnement-SA company, Poissy, France
N. VerdierCNES, Toulouse, France
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)
Optical aerosols measurements (counter, lidar, photometer)
Sparse in situ measurements with strong constraints:
- High costs facilities and complex installation (aircrafts and balloons)
- Technical limitations (how to fly during strong volcanic eruption?)
Aerosol counter operated in the middle atmosphere, below 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
- Concentration measurements in different size classes
LOAC : Light Optical Aerosol Counter(patented concept)
Measurements at 2 scattering angles :Where the scattered light is insensitive to the aerosols nature
Where the scattered light is strongly sensitive to the aerosols nature
Combining the measurements Accurate determination of the size distribution
Estimation of the main nature of the aerosols
Aerosols Laser
LOAC was design and tested in French by research institutes and by the Environnement-SA company
Meteo balloon gondola (including PTU sensors and telemetry) MeteoMODEM company
LOAC
20 size classes in the 0.4 - 100 m range
Optical chamber and pump: 250 grams
4 hours with 2 alkaline batteries of 4.5 V
Meteo balloon gondola : 850 grams
Long duration stratospheric balloon
Meteo balloon
Low altitude troposheric balloon
Kiruna, Northern Sweden, 1 April 2011 (large stratospheric balloon, onboard German gondola TWIN, CNES launch)
Strong variability of aerosol content
West Iceland, 20 July 2011 (meteo balloon, Iceland meteo office launch)
Clean stratosphere event
Identification of the main nature of aerosols in 4 size classes
(typically <1m, 1-5 m, 5-20 m, > 20m)
from the ratio of the 2 channels measurements
- Liquid/ wet aerosols
- Carbon particulates (soot)
- Mineral dust (sand)
Sausset-les-Pins (France), 28 June 2012 (meteo balloon, CNES)
Flights during an strong
episode of sand above
Mediterranean sea
Size grains : 5-30 m
Sand
Soot (pollution)
Sea droplets
Candillargues (France), 23 September 2012 (MeteoFrance)
Hymex campaign
Sand
Small liquid
background aerosols
Clouds/haze
Applications (under meteo balloons)
Better determination of the size distribution and concentration for :
- Pollution aerosols
- Transported atmospheric sand
- Volcanic ashes (aviation)
Determination of the main nature of the aerosols in the various parts of the atmosphere
LOAC is already involved in several scientific projects
Winter 2012-2013: ParisFog, study of fog, tethered balloon
Summer 2013: Charmex campaign, study of aerosols transport above Mediterranean sea (30 LOAC)
End of 2013: Aerowave , stratospheric aerosols content and variability, large stratospheric balloons
2018 : Strateole phase 2, tens of long-duration stratospheric balloons above equatorial regions