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

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)

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

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)

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.

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

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

- 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

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)

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”

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

Bauru (Brazil), 13 March 2012 (stratospheric balloon, Reims University “Tropico project”)

Several enhancements of “large” particles around 10 μmSoot particles ?

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

At ground, liquid aerosols (launch on the beach)

On the middle troposphere, sand

DataCarbonMineralDroplets

DataCarbonMineralDroplets

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