Aerosol counting measurements with the LOAC light instrument using weather balloons - Future applications for the Asian Tropopause Aerosol Layer ACAM Workshop, 9 June 2015 Gwenael BERTHET, Damien VIGNELLES, Jean-Baptiste RENARD, Fabrice JEGOU, Thibaut LURTON, Matthieu JEANNOT, Benoît COUTE, Vincent DUVERGER LPC2E-CNRS, Orléans, France Jean-Paul VERNIER Science Systems and Applications, Inc, NASA Langley Research Center Hampton, Virginia, USA François DULAC LSCE-CEA / IPSL, CEA Saclay 701, 91191 Gif-sur-Yvette, France
Transcript
Aerosol counting measurements with the LOAC light instrument using weather balloons
-Future applications for the Asian Tropopause Aerosol Layer
Science Systems and Applications, Inc,NASA Langley Research Center
Hampton, Virginia, USA
François DULAC
LSCE-CEA / IPSL, CEA Saclay 701, 91191 Gif-sur-Yvette, France
Sources of aerosols in the upper troposphere and lower stratosphere
Need for observations of aerosol size distributions to assess Chemistry Climate Models or estimate theirradiative/chemical impacts
Only a few in situ aerosol instruments (e.g. counters) mounted onboard aircrafts or balloon platforms
+organics?
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 gElectric consumption: ~3 W
Concentrations for 19 size classes between 0.2 and ~50 m (diameters)
Automatic check every 10 minutes and electronic recalibration if necessary (ex. strong changes in temperature)
Uncertainties: 60% for concentrations <10-2 cm-3, 20% for 10-1 cm-3, 6% for concentrations > 1 cm-3
Principle of measurements2 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 of particles:
- 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)
Spe
ciat
ion
inde
x
Pollution carbonaceous particles Saharan sand plume
LOAC is used at ground and under all kinds of balloons for scientific purposes
tethered, weather, low troposphere, stratosphere
In the Boundary Layer: fog events
south suburbs of Paris
End of the fog
Welas and Fog Monitor : optical counters
Size distribution
topology
12°angle
In the Boundary Layer: pollution eventsStrong 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 particlesWeather Balloon flights in Iceland, one inside the Holuhraun volcano plume
LOWER STRATOSPHERE: VOLCANIC PLUME IN THE TROPICS
LOAC concentration aerosols and LIDAR profilesPreliminary results
The balloon has crossed two volcanic plumes- the Piton de la Fournaise plume around 3 km- the Calbuco plume around 18 km
Piton de la Fournaise
plume
CalbucoChilean volcano plume
Flight performed from the Réunion IslandOn may 19th 2015 (Morgane campaign)
11 March 2015
ALT
ITU
DE
(km
)
dN/dLogD (cm-3)
12 January 2015
ALT
ITU
DE
(km
)
dN/dLogD (cm-3)
Stratosphere: example of mid-latitude profiles (44°N 0°E)Recurrent launches (2 per week) from a mid-latitude site (44°N, 0°E) to explore stratospheric aerosol variability
Application of this aerosol sounding strategy to the study of the Asian Tropopause Aerosol Layer (ATAL)
Vernier et al., GRL, 2011; JGR, 2015
See oral presentation from Jean-Paul Vernier
- 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 aerosolformation
- Aerosol composition in the lower part of the ATAL: carbonaceous and sulfate material
Application of this aerosol sounding strategy to the study of the Asian Tropopause Aerosol Layer (ATAL)
BATAL 2015 campaign
1 kg LOAC version for weather balloons
Managed by Jean-Paul VernierExpected launches of LOAC from Varanasi in August 2015
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 campaignExpected results:
- Size distributions of aerosols in the ATAL for diameters in the 0.2-50 µm 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
SUMMARY● LOAC instrument
- Can provide size distribution (0.2 - 50 µm) 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
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
