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