ESA-JAXA Pre-Launch EarthCARE
Science and Validation
Workshop

13 – 17 November 2023 | ESA-ESRIN, Frascati (Rome), Italy

EVID 12: LITES
optical, microphysical and chemical characterization of aerosols with lidar
Detlef Müller / University of Hertfordshire and Wuhan University
andBoyan Tatarov / University of Hertfordshire

University of Hertfordshire - in the south-east of the United Kingdom,
approximately 40 km to the north of London
Location of LITES allows
for observations of• smoke (NA, SW Europe)• dust from NW Africa• “London plume”

LondonCHART OF UNITED
KINGDOM AIRSPACERESTRICTIONS AND
HAZARDOUS AREAS

Multi-channel Lidar Spectrometer as part of LITES
 Lidar Innovations for Technologies and Environmental Sciences (LITES)
design, construction, operational: 2012 - 2022

Main Laser System: Nd:YAG + OPO
up to 7 J at 1064 nm (10 Hz)

Main Spectrometer
Horiba 1250M-SII Specifications.

Combine 3 Steps in Particle Characterization
1. Optical properties – use LIDAR (as part of LITES) for exploratory studies• Aerosol types over UK – for extending existing knowledge• Depolarization ratio - could be used for tests of new particle light-scattering models
2. Microphysical Properties – use TiARA (Tikhonov Advanced Regularization Algorithm)• Test new TiARA versions for improved particle characterization• Use TiARA for quality assurance
3. Chemical Properties – use LITES (lidar, aerosol chambers, single-particle analysis)• Can we identify chemical components from Raman lidar observations?
• Can we add this knowledge to improved microphysical retrievals?
• Can we improve aerosol typing (e.g. aerosol components)?

Lidar observations of linear depolarization
ratio by lidar with circular polarized lasertransmitter at Hatfield, United Kingdom
Boyan Tatarov and Detlef Müller
13 September 2023
European Lidar Conference, Cluj/Romania 2023

Examples of linear and circular depolarization measurements
10 September 2023, averaged over 18600 laser shots (31 min)10 September 2023, Averaged over 39600 laser shots (66 min)LinearVDRWork carriedout in context ofAeolus cal/val
CircularVDR
 use data for testing new particle light-scattering models
 at present microphysical data inversion• rests on the use of data for which particle depolarization ratio is 0
• thus no analysis of observations of e.g. mineral dust, volcanic ash, ...

Identification of “Chemical Signatures” of Particles
South Korea, 2008 to 2016
mixed pollution plumes - separatingmineral quartz from other aerosol types(Müller, Tatarov, Noh. et al)Forest Fire Smoke(spring, summer,fall)
Asian Dust
(spring andfall)

JapanKorea

China

Gwangju
Anthropogeni (GIST)c Aerosols(all year)

SiO2

Methodology
We use the relation of the Raman backscatter coefficient to theRaman backscatter differential cross section d(L,R,)/d andthe number density of quartz molecules Nq.

→d (L , R , )
R (r, L , R )  Nq (r)d
we assume:
power-4 dependence between
546 (emission at 532 nm) and 360 (355 nm)- significantly dependent on the structure of the crystal and the crystallization process- we need more studies for quartz in mineral dust particles.

Example of the first measurement with optimized instrument
Quartz concentration profile: „super dust outbreak“ Korea 2010
Quartz Angstrom Ex.
152

3

45Müller et al., Geophy. Res. Let., 2010
first results

6360nm
546 nmHeight (km)4Tatarov et al., Opt. Exp., 2011
instrument

32100Noh et al., Chemosphere, 2016
overview
246810Quartz BSC COEFF.
9-1 -1(10 Mm sr )0102030
QUARTZ CONC-3(gm )40

Transfer Experience From These Studies to LITES:
Laboratory Experiments with Raman/Fluorescence Microscope
Microscopevisualization
camera40 different dust samples
from desert regions

SampleICCD

532nm CleanDPSS up Filter,
Laser
532nm

Edge
FilterSpectrometer

Aluminum oxide, Quartz, Kaolinite,
Dolomite, Goethite, Calcite, …

Results: Corundum (AL2O3)

Raman lines of corundum

Position of luminescence features

Raman spectrum of corundum

Reference [3] observation:
378, 418, 432, 451, 578, 645, 751

Signal strength of emission
line of corundum shows that
atmospheric Al2O3 molecules
can be detected with lidar.

Emission lineRuby Laser
wavelength:694.3 nmEC - Marie Skłodowska Curie Programme (2017)
European Commission

LIDAR Project CAPABLE

Chemical composition characterizationof Air Pollution (Aerosols and gases) on
the Basis of nonlinear multi-channel
Lidar Experiments

Future Work with LITES: „Chemical Fingerprint“
aerosol types versus aerosol components
OPAC (Database on Optical Properties of Aerosols and Clouds, Hess et al. 1998)
Aerosol components
microphysics, chemistry, morphology
Insoluble
Water-soluble
Soot
Sea-salt: accumulation modecoarse mode
Mineral: nucleation mode
accumulation modecoarse modetransported
Sulfate droplets

Aerosol types
opticsContinental: clean
averagepolluted
Urban
DesertMaritime:clean
polluted
tropicalArctic
Antarctic
Mineral transported
Free troposphere
Stratosphere

Second GALION Workshop, WMO, Geneva, 20-23 September 2010