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