Aerosol counting measurements with the LOAC light instrument using weather balloons Gwenael BERTHET,...
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Transcript of Aerosol counting measurements with the LOAC light instrument using weather balloons Gwenael BERTHET,...
Aerosol counting measurementswith the LOAC light instrument
using weather balloons
Gwenael BERTHET, Damien VIGNELLES, Jean-Baptiste RENARD, Fabrice
JEGOU, Thibaut LURTON, Matthieu JEANNOT, Benot COUTE, Vincent
DUVERGER LPC2E-CNRS, Orlans, France Franois DULAC LSCE-CEA / IPSL,
CEA Saclay 701, Gif-sur-Yvette, France MeteoModem, Environnement SA
and Aerophile private companies Sources of aerosols in the upper
troposphere and lower stratosphere
+organics? Need for observations of aerosol size distributions to
assess Chemistry Climate Models or estimate their
radiative/chemical impacts Only a few in situ aerosol instruments
(e.g. counters) mounted onboard aircrafts or balloon platforms
stratospheric sulfate aerosols
SPARC Aerosol Assessment, 2006 Gaseous precursors: SO2 and OCS
(carbonyl sulfide) Light Optical Aerosol Counter
Collaboration between national research laboratory, 2 private
companies, and the French Space Agency More than 90 copies produced
at mid-2015 (now a commercial instrument sold by the MeteoModem
company) Technical details: Instrument and pump: 300 g Electric
consumption: ~3 W Concentrations for 19 size classes between 0.2
and ~50 mm (diameters) Automatic check every 10 minutes and
electronic recalibration if necessary (ex. strong changes in
temperature) Uncertainties: 60% for concentrations 1 cm-3 Principle
of measurements
2 scattering angles measurements (field of view of few degrees)
~12, insensitive to the refractive index of the particles (mainly
diffraction) => accurate size determination and counting ~60,
strongly sensitive to the refractive index of the particles =>
indication of the nature of the particles Detection of the maximum
of intensity for particles that cross the laser beam Real-time
stray light correction The 12/60 ratio is compared to charts
obtained in laboratory for different families ofparticles:
- Liquid droplets - Minerals - Carbons This is an open data base
and other natures of particles can be considered (no more than 3 or
4 different natures) Speciation index Pollution carbonaceous
particles
Saharan sand plume Pollution carbonaceous particles Size
distribution Size distribution 12 angle 12 angle topology topology
Light => high reactivity of use
LOAC is used at ground and under all kinds of balloons for
scientific purposes tethered, weather, low troposphere,
stratosphere + On-board Unmanned Airborne Vehicles (Fly-N-Sense
Society) In the Boundary Layer: fog events
south suburbs of Paris 12 angle Size distribution End of the fog
Welas and Fog Monitor : optical counters topology In the Boundary
Layer: pollution events
Counting measurements can be converted to PM2.5 and PM10 mass
(mg/m3) Comparison with microbalance measurements from Airparif
ambient air network In the Boundary Layer: pollution events
Strong pollution event of 11 December 2013 At 200m, carbonaceous
particles In the free troposphere: Mediterranean aerosols (CHARMEX
campaign) Comparison with lidar and sunphotometer measurements LOAC
data converted to extinction and to integrated volume
concentrations Tropospheric volcanic particles
Weather Balloon flights in Iceland, one inside the Holuhraun
volcano plume lower stratosphere: Volcanic plume in the
tropics
Flight performed from the Runion Island On may 19th 2015 (Morgane
campaign) CalbucoChileanvolcanoplume The balloon has crossed two
volcanic plumes - the Piton de la Fournaise plume around 3 km - the
Calbuco plume around 18 km Piton de laFournaise plume LOAC
concentration aerosols and LIDAR profiles Preliminary results
Stratosphere: example of mid-latitude profiles (44N 0E)
Recurrent launches (2 per week) from a mid-latitude site (44N, 0E)
to explore stratospheric aerosol variability 11 March 2015 12
January 2015 ALTITUDE (km) ALTITUDE (km) dN/dLogD (cm-3) dN/dLogD
(cm-3) Application of this aerosol sounding strategy to the study
of the Asian Tropopause Aerosol Layer (ATAL) Formation of an
aerosol layer in the tropopause region in the Asian monsoon
anticyclone Connection with deep convective processes over the
Indian subcontinent Indication of production of secondary aerosol
formation Aerosol composition in the lower part of the ATAL:
carbonaceous and sulfate material Vernier et al., GRL, 2011; JGR,
2015 Application of this aerosol sounding strategy to the study of
the Asian Tropopause Aerosol Layer (ATAL)BATAL 2015 campaign
Managed by Jean-Paul Vernier Expected launches of LOAC from
Varanasi in August 2015 1 kg LOAC version for weather balloons The
instrument must fly alone because electronics in this configuration
are sensitive to electromagnetic radiation Application of this
aerosol sounding strategy to the study of the Asian Tropopause
Aerosol Layer (ATAL)BATAL 2015 campaign Expected results: Size
distributions of aerosols in the ATAL for diameters in the m range
Information about their type, e.g. signature carbonaceous material
confirmed ? Possible detection of cirrus clouds if any Example of
size distributions recorded in the troposphere Future - Improved
version of LOAC in development
- Flight of several hours in the stratosphere (large stratospheric
balloons, Canada) - Detection of charged aerosols - Flights on
alert in case of strong (Icelandic) volcano eruption, in the
tropics (La Runion site) - STRATEOLE, balloon flights of several
months in the lower equatorial stratosphere - Space application :
Studies of planetary atmospheres (at present, participation to a
proposal for the Saturnatmosphere) SUMMARY LOAC instrument
Campaigns
- Can provide size distribution ( m) and information on main type
of aerosols - Light instrument for ground and airborne
measurements, high reactivity for launching - Development between
the CNRS National institute and private companies but now a
commercial instrument - Many ground-based comparisons with other
instruments (other counters, microbalances, lidars) paper in
revision in AMTD Campaigns - Pollution and fog studies in urban
areas (ground, tethered balloons), transport of Saharian sand
particles - ~25 flights per year at different latitudes (France,
Iceland, Indian Ocean) for the in situ monitoring of the
stratosphere (as done from Univ. of Wyoming) using weather balloons
(similar strategy as done for ozone soundings throughout the world)
Short-term: BATAL 2015: next August from Varanasi for the study of
the ATAL Regular flights from La Runion Island Longer term: -
Improved version in development (better signal-to-noise ratio,
electronics, more scattering angles) - Flights on alert in case of
volcanic eruptions - Balloon flights of several months in the lower
equatorial stratosphere (STRATEOLE2 project) - Space application :
Studies of planetary atmospheres