detailed characterization of aerosol scattering properties · 2011. 8. 10. · • in situ...
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Detailed Characterization of Aerosol Scattering Properties
(Polarimeter Capabilities Theory and Instruments)
J. Vanderlei Martins1, Gergely Dolgos1, Roberto Fernandez-Borda1, Adriana Rocha Lima1, Leroy Sparr2, Lorraine
Remer2
1- UMBC/LACO – JCET2- NASA GSFC
Glory Science Team Meeting – NASA GISS 10-12 August 2011
Holistic Aerosol Characterization Approach
• Laboratory generation and characterization– Natural– Artificial particles
• In situ measurements– Ground Based– Aircraft
• Remote Sensing– Aircraft– Satellite
Produce a database of aerosol particle scattering (and spectral absorption) properties with different particle size, shape, composition
Develop instrumentation and Methods for the polarized hyper-angular measurement of aerosol and cloud particles.
Dust – Collected at UMBC.
Before a) and after b) sieving: particles < 43mm.
FBAG – Fluidized Bed Aerosol Generator
a) b)
Dry Aerosol Generation:
Dry Aerosol GenerationSolid Material » De-agglomeration/Re-suspension » Dry/Humidified aerosols:
Volcano Eija 2010 UMBC Dust b)
Wet and Dry Aerosol Generation
Cubic NaCl Particles
Chemical solutions » Water Droplets » dry/humidified aerosols
Detailed Aerosol Scattering Properties:
Detailed Aerosol Scattering Properties:
Polarized Imaging Nephelometer
• Funded as part of the Langley DEVOTE project– Develop a Polarized Imaging (Polar) Nephelometer
system to characterize the angular distribution of light scattering by aerosol particles
– Demonstrate these measurements inside the Langley B-200 aircraft
• As part of the Glory project we plan to Extend the PI-Neph application by characterizing laboratory and in-situ particles on the ground and aircraft
The Scattering Phase Matrix
Ωincident (θ = 0, φ = 0)
Ωscattered (θ, φ)
Δω
(solid angle element)
θ
φ:
azimuth scattering angle θ: polar scattering angle
⎟⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜⎜
⎝
⎛
in
in
in
in
VUQI
⎟⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜⎜
⎝
⎛
sca
sca
sca
sca
VUQI
φscatterers
Gergely
Dolgos, J. Vanderlei
Martins 9
=
Polarized Imaging Nephelometer
Monday, September 20, 2010 Gergely
Dolgos, J. Vanderlei
Martins 10
I, Q, U
IMAGER
100°
FOV
LASER BEAMS
L = D / tan(θmin ) ~ 1 m
θmin
~ 2°45°
D ~ 1 cm
back scattering
forward scattering
MIRRORS
OBJECTIVE θmin
~ 2°
θmax
~ 178°
Image Data Reduction
LACO PI-Neph Prototype
0 20 40 60 80 100 120 140 160 1801
2
468
10
20
4060
N2 Rayleigh CO 2 Rayleigh N2 Data CO 2 Data Aerosol
F 11(θ
) : P
hase
Fun
ctio
n [A
U]
scattering angle [degrees]
Gergely
Dolgos, J. Vanderlei
Martins 12
F11 Raw Data:
Polarized Phase Function:
Fixed LP
LCVRFixed at 45°
AQWPFixed at 0°
Gergely
Dolgos, J. Vanderlei
Martins 13
( )( )( )( )
iin
iin
iin
iin
iin
S
VUQI
=
⎟⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜⎜
⎝
⎛
ΨΨΨΨ
Time:
Output Images:
0 s 1 s 2 s 3 s
Input
Polariz:
IQU
λ1
IQU
λ2
IQU
λ3
Setup 1: Polarized beam + 1 Unpolarized Camera: Rotate & measure scattering at each wavelength
Fixed LP
LCVRFixed at 45°
AQWPFixed at 0°
Gergely
Dolgos, J. Vanderlei
Martins 14
( )( )( )( )
iin
iin
iin
iin
iin
S
VUQI
=
⎟⎟⎟⎟⎟
⎠
⎞
⎜⎜⎜⎜⎜
⎝
⎛
ΨΨΨΨ
Time:
Output Images:
0 s 1 s 2 s 3 s
Input
Polariz:
IQUV
IQUV
IQUV
1,λ1 2,λ1 3,λ1
IQUV
IQUV
IQUV
1,λ2 2,λ2 3,λ2
IQUV
IQUV
IQUV
1,λ3 2,λ3 3,λ3
Setup 2: Polarized beam + 4 Polarized Cameras: Rotate & measure scattering at each wavelength
Scattering Camera
Retro- reflector
Mai
n B
ody
colimators
Laser beams
Lase
r Box
Elec
tron
ics
Inle
tO
utle
t
Currently testing in the Lab – plan to integrate to NASA Langley Aircraft Sept/11
Alternatives for Polarized Remote Sensing Measurements
HARP (or PACS) – Hyper-angular Rainbow Polarimeter
PACS/HARP Imaging Polarimeter
Goal:
PACS/HARP Imaging Polarimeter
PACS/HARP:Compact hyper-angular, Multi-Spectral Imaging Polarimeter with no operational moving parts
VNIR component to fly in 2011
I0(λ)
I90(λ)I45(λ)
IλQλ
Uλ
-1 IoI45I90
Backup Materials
Design and Lab Tests45O
Alignment Mirror Mount
Liquid Crystal Variable RetarderAchromatic Quarter Wave plate
Linear polarizer
Reference detector
Beam Splitter
Gergely
Dolgos, J. Vanderlei
Martins 22
Automatic Aerosol Sampling
Station for Fennec
Experiment in the Sahara June 2011.
Automatic Controller
Multi-filter Inlet
• Aerosol filter collection• Spectral Absorption• Scattering Coefficient
Airborne Open Nephelometer
Monday, September 20, 2010 Gergely
Dolgos, J. Vanderlei
Martins 24
Scanning Electron Microscopy of Aerosols:(Black Circles are filter pores)
by: Martin Todd, Gill Lizcano(UCL)
0
0.05
0.1
0.15
0.2
0.25
0.3
300 600 900 1200 1500 1800 2100 2400Wavelength (nm)
Abs
. Eff
. (m
2/g)
AeronetAVG and Stdev Dust 2AVG and Stdev Dust 1
Bodele Dust
by: Martin Todd, Gill Lizcano(UCL)
LACO Sampling Station sent to Sahara Fennec Experiment July 2011
Things to add
• New data figure from Gergely• New pictures from Gergely FER
presentation• Picture of PACS aircraft setup• PACS Calibration data