remote sensing of atmosphere-ocean systems in the uv · pre-aerosol, clouds, and ocean ecosystem...
TRANSCRIPT
Jacek Chowdhary1 Brian Cairns1,3
Remote sensing of atmosphere-ocean systems in the UV:
How can polarimetry help distinguish reflectance variations
caused by absorbing aerosols from variations caused by CDOM?
1 Columbia University, New York, USA
NASA Ocean Color Research Team meeting
2 NASA/Goddard Institute for Space Studies, New York, USA
PACE Mission
In autumn of 2011 NASA selected a science definition team (SDT) to provide (within 3 years) thescience justification and measurement, as well as mission requirements, for the PACE mission
In autumn of 2014 NASA selected a science team (ST) to pursue studies on inherent opticalproperties (IOPs) and Atmospheric Correction (AC)
Responding to the Challenge of Climate
and Env ironmental Change
National Aeronautics and Space Administration
The Pre-Aerosol, Clouds, and ocean Ecosystem (PACE) mission
will make essential global ocean color measurements, essentialfor understanding the carbon cycle and how it both affects and
is affected by climate change, along with polarimetry
measurements to provide extended data records on clouds and
aerosols.
Pre-Aerosol, Clouds, and ocean Ecosystem (PACE)
“The PACE mission will extend key climate data records whose future was in jeopardy
prior to the FY2011 budget request. Global ocean color measurements, essential forunderstanding the carbon cycle and how it affects and is affected by climate change, will
be made by a radiometer instrument on this mission. A polarimeter instrument will
extend data records on aerosols and clouds using this approach begun by the French
PARASOL mission and expanded upon by NASA’s Glory mission, as well as multi-spectral and multi-angle measurements made by NASA’s MODIS and MISR instruments
on NASA’s EOS platforms (MODIS on terra and Aqua, MISR on Aqua).”
NASA’s plan for a Climate-Centric Architecture for Earth Observations and Applications from Space
June 2010
• Primary mission: Ocean; Secondary mission: atmosphere
• Atmospheric Correction: polarization
o hyperspectral between 800-900
nm, 1-2 nm subsamples (O2 A)
PACE Mission
o 3 SWIR bands
(1240, 1640, 2130 nm)
o spatial resolution = 1 km2
o improved global coverage (1 day)
o spatial resolution better than
500m × 500m
Threshold Ocean Questions SQ 1-7
Goal Terrestrial Questions TSQ 1-3
OCI †
OCI/OG OCI Questions (SQ 1-7, TSQ 1-3)
Goal Coastal Questions CSQ 1-4
o Hyperspectral imager with 5 nm
resolution between 350-800 nm
o 2 NIR bands
(incl. 865 nm)
o OCI instrument capabilities
Option Science Threshold and Goal Questions Brief Instrument Description
Oce
an
Scie
nce o 3 SWIR bands
(1240, 1640, 2130 nm)
o spatial resolution = 1 km2
Note: Threshold Questions define required
research, i.e. they must be addressed
† OCI = Ocean Color Imager ‡ improved atmospheric correction, data continuity for POLDER products§ data continuity for MISR products, albeit with coarser spatial resolution¶ 3M = Multi-directional, Multi-polarization, Multi-spectral
OCI+
OCI-3M ¶
OCI/A
OCI/A-3M
OCI Questions (SQ 1-7, TSQ 1-3)
“Threshold” Atmosphere Question ASQ 1
OCI Questions (SQ 1-7, TSQ 1-3)
Goal Atmosphere Questions ASQ 4,5
OCI+ Questions (SQ 1-7, TSQ 1-3, ASQ 1)
Goal Atmosphere Question ASQ 2
o OCI instrument capabilities
o 3 additional NIR and SWIR
bands (940, 1378, 2250 nm)
o OCI instrument capabilities
o a 3M imager ‡ §
o OCI+ instrument capabilities
o selected atmospheric bands at
spatial resolution 250m × 250m
OCI-3M & OCI/A Questions (SQ 1-7,
TSQ 1-3, ASQ 2,4,5)
Goal Atmosphere Question ASQ 3
o OCI/A instrument capabilities
o a 3M imager ‡ §
Atm
osp
he
re S
cie
nce
absorbingaerosols
CDOM
phytoplankton
pigments
functional groups
particle sizes
physiology
pigment
fluorescence
coastal biology
atmosphericcorrection
(clear ocean)
atmosphericcorrection
(coastal ocean)
SW
IRN
IRV
isib
leU
ltra
vio
let
5 n
m r
eso
luti
on
(3
50
-885
nm
)
26
re
qu
ire
d “m
ult
isp
ectr
al” b
an
ds
3 S
WIR
ba
nd
s
products
PACE Mission
NO2
UV-A Visible NIR SWIR
aerosol absorption
dark ocean
aerosol scattering
black oceanocean science products
Atmospheric Scattering (AS) estimate
NIR & SWIR band ratios: select aerosol scattering model
UV-A radiance: detect (& constrain?) aerosol absorption
AS
~ρw (412)
10–110–2 100 101
10–2
10–1
100
101
Sa
telli
te
In Situ
Santa Barbara Channel, CA
٭ MODIS
+ SeaWiFS
absorbingaerosols
CDOM
phytoplankton
pigments
functional groups
particle sizes
physiology
pigment
fluorescence
coastal biology
atmosphericcorrection
(clear ocean)
atmosphericcorrection
(coastal ocean)
SW
IRN
IRV
isib
leU
ltra
vio
let
5 n
m r
eso
luti
on
(3
50
-885
nm
)
26
re
qu
ire
d “m
ult
isp
ectr
al” b
an
ds
3 S
WIR
ba
nd
s
products
Source: D. Siegel (pers. com.)
PACE Mission
NO2
UV-A Visible NIR SWIR
aerosol absorption
dark ocean
aerosol scattering
black oceanocean science products
Atmospheric Scattering (AS) estimate
NIR & SWIR band ratios: select aerosol scattering model
UV-A radiance: detect (& constrain?) aerosol absorption
AS
~ρw (412)
10–110–2 100 101
10–2
10–1
100
101
Sa
telli
te
In Situ
Santa Barbara Channel, CA
٭ MODIS
+ SeaWiFS
absorbingaerosols
CDOM
phytoplankton
pigments
functional groups
particle sizes
physiology
pigment
fluorescence
coastal biology
atmosphericcorrection
(clear ocean)
atmosphericcorrection
(coastal ocean)
SW
IRN
IRV
isib
leU
ltra
vio
let
5 n
m r
eso
luti
on
(3
50
-885
nm
)
26
re
qu
ire
d “m
ult
isp
ectr
al” b
an
ds
3 S
WIR
ba
nd
s
products
When is the ocean bright enoughto retrieve variations in CDOM?
When is the ocean dark enoughto retrieve variations in aerosolabsorption?
Source: D. Siegel (pers. com.)
RT Comparison studies
Motivation
Results
1) Accuracy for Stokes parameters I, Q, Uemerging from various AOS is better than 10–6
2) Corresponding accuracy in degree of linear polarization better than 0.1%
Part I
RT comparison Studies
Motivation Polarization is an extremely useful tool to retrieve aerosol properties
Synthetic TOA data of I, Q, & U:
o Fine mode aerosol, τ = 0.2
(re = 0.4 μm; ve=0.2; m=1.45
o Rough ocean surface
(W = 7 m/s)
o Black water body
o μ0=0.8; μ=0.2, 0.4, 0.6, 0.8, 1.0
Δφ=60º & 120º
θ0 ≡ π – ϑ0
oce
an
atm
osp
her
e
x
y
zsun
k0
φ0 = 0º
view
k
ϑ
φ
AOS system
provided that the percent linear polarized light (“DLP”) is measured with high accuracies (0.2% - 0.5%)
Source: Mishchenko and Travis, JQSRT 102:13,543-13,553 (1997)
Simulated aerosol retrieval from space-borne observation over ocean at 865 nm
Aerosol candidate models:
o Fine mode aerosol:
τ = 0.01 – 0.4, Δτ = 0.01
re = 0.01 – 0.8 μm, Δre = 0.01
m = 1.3 – 1.7, Δm = 0.01
ω = 0.78 – 1.00, Δω = 0.02
ve = 0.2
>350,000 aerosol candidate models
RT comparison Studies
Motivation
Aerosol candidate models:
o Fine mode aerosol:
τ = 0.01 – 0.4, Δτ = 0.01
re = 0.01 – 0.8 μm, Δre = 0.01
m = 1.3 – 1.7, Δm = 0.01
ω = 0.78 – 1.00, Δω = 0.02
ve = 0.2
>350,000 aerosol candidate models
Source: Mishchenko and Travis, JQSRT 102:13,543-13,553 (1997)
ω=1.00 ω=0.98
ω=0.94 ω=0.92
optic
al th
ickn
ess
optic
al th
ickn
ess
refractive index refractive index
o radiance I,
o 9 viewing angles
o ΔI = 4%
o polarization Q/I and U/I,
o 9 viewing angles
o ΔP = 0.2%
Simulated aerosol retrieval from space-borne observation over ocean at 865 nm
Polarization is an extremely useful tool to retrieve aerosol properties
RT comparison Studies
provided that the percent linear polarized light (“DLP”) is measured with high accuracies (0.2% - 0.5%)
Motivation
o radiance I,
o 9 viewing angles
o ΔI = 6%
o polarization Q/I and U/I,
o 9 viewing angles
o ΔP = 0.8%
optic
al th
ickn
ess
optic
al th
ickn
ess
refractive index refractive index
ω=1.00 ω=0.98
ω=0.94 ω=0.92
Simulated aerosol retrieval from space-borne observation over ocean at 865 nm
Source: Mishchenko and Travis, JQSRT 102:13,543-13,553 (1997)
Polarization is an extremely useful tool to retrieve aerosol properties
Aerosol candidate models:
o Fine mode aerosol:
τ = 0.01 – 0.4, Δτ = 0.01
re = 0.01 – 0.8 μm, Δre = 0.01
m = 1.3 – 1.7, Δm = 0.01
ω = 0.78 – 1.00, Δω = 0.02
ve = 0.2
>350,000 aerosol candidate models
RT comparison Studies
provided that the percent linear polarized light (“DLP”) is measured with high accuracies (0.2% - 0.5%)
Motivation
o radiance I,
o 9 viewing angles
o ΔI = 8%
o polarization Q/I and U/I,
o 9 viewing angles
o ΔP = 2.0%
optic
al th
ickn
ess
optic
al th
ickn
ess
refractive index refractive index
ω=1.00 ω=0.98
ω=0.94 ω=0.92
Simulated aerosol retrieval from space-borne observation over ocean at 865 nm
Source: Mishchenko and Travis, JQSRT 102:13,543-13,553 (1997)
Polarization is an extremely useful tool to retrieve aerosol properties
Aerosol candidate models:
o Fine mode aerosol:
τ = 0.01 – 0.4, Δτ = 0.01
re = 0.01 – 0.8 μm, Δre = 0.01
m = 1.3 – 1.7, Δm = 0.01
ω = 0.78 – 1.00, Δω = 0.02
ve = 0.2
>350,000 aerosol candidate models
RT comparison Studies
provided that the percent linear polarized light (“DLP”) is measured with high accuracies (0.2% - 0.5%)
2015:
~1e-4
~1e-4
~1e-4
absolute difference
I
Q
UAOS system: molecular atmosphere above ocean surface
view angle
0 20 40 60 80
view angle
0 20 40 60 80
Polarization is an extremely useful tool to retrieve aerosol properties
our forward RT computations need to match these high accuracies in DLP !
Motivation
RT comparison Studies
provided that the percent linear polarized light (“DLP”) is measured with high accuracies (0.2% - 0.5%)
Results
θ0 ≡ π – ϑ0
oce
an
atm
osp
her
e
x
y
z
k0
φ0 = 0º
k
ϑ
φ
upper
lower
2 sun angles
13 viewing angles
4 azimuth angles
TOA
SRF
>100 scattering geometries x 2 altitudes
λ = 350 nm, 450 nm, 550 nm, 650 nm
Polarization is an extremely useful tool to retrieve aerosol properties
I, Q, U ΔP ≤ 0.1%
RT comparison Studies
models Ocean Body Ocean Surface Atmosphere
AOS-I
none
rough Gaussian isotropic No foam or shadowing
molecular Pure Rayleigh scattering
AOS-II pure water Pure Rayleigh scattering
rough Gaussian isotropic No foam or shadowing
none
AOS-III pure water Pure Rayleigh scattering
rough Gaussian isotropic No foam or shadowing
molecular Pure Rayleigh scattering
AOS-IV pure water & hydrosol Pure Rayleigh scattering Detritus-Plankton mix
rough Gaussian isotropic No foam or shadowing
molecular Pure Rayleigh scattering
AOS-V pure water & hydrosol Pure Rayleigh scattering Detritus-Plankton mix
rough Gaussian isotropic No foam or shadowing
molecular & aerosol Pure Rayleigh scattering Fine-mode aerosol
provided that the percent linear polarized light (“DLP”) is measured with high accuracies (0.2% - 0.5%)
our forward RT computations need to match these high accuracies in DLP !
Results
10
–10
5
0
–5
–60–40–20 0 20 40 60
dI (x106) dQ (x106) dU (x106) dDLP (%)
SRF, θ0=60° SRF, θ0=60° SRF, θ0=60° SRF, θ0=60°10
–10
5
0
–5
–60–40–20 0 20 40 60
10
–10
5
0
–5
–60–40–20 0 20 40 60
0.2
–0.2
0.1
0.0
–0.1
–60–40–20 0 20 40 60
φ = 60° φ = 120°←║ φ = 60° φ = 120°←║ φ = 60° φ = 120°←║ φ = 60° φ = 120°←║
AOS-I (550 nm)
view angle view angle view angle view angle
Polarization is an extremely useful tool to retrieve aerosol properties
GSFCJPLNRL
UCSDUMBC
RT comparison Studies
models Ocean Body Ocean Surface Atmosphere
AOS-I
none
rough Gaussian isotropic No foam or shadowing
molecular Pure Rayleigh scattering
AOS-II pure water Pure Rayleigh scattering
rough Gaussian isotropic No foam or shadowing
none
AOS-III pure water Pure Rayleigh scattering
rough Gaussian isotropic No foam or shadowing
molecular Pure Rayleigh scattering
AOS-IV pure water & hydrosol Pure Rayleigh scattering Detritus-Plankton mix
rough Gaussian isotropic No foam or shadowing
molecular Pure Rayleigh scattering
AOS-V pure water & hydrosol Pure Rayleigh scattering Detritus-Plankton mix
rough Gaussian isotropic No foam or shadowing
molecular & aerosol Pure Rayleigh scattering Fine-mode aerosol
provided that the percent linear polarized light (“DLP”) is measured with high accuracies (0.2% - 0.5%)
our forward RT computations need to match these high accuracies in DLP !
Results
10
–10
5
0
–5
–60–40–20 0 20 40 60
dI (x106) dQ (x106) dU (x106)
SRF, θ0=60° SRF, θ0=60° SRF, θ0=60° SRF, θ0=60°10
–10
5
0
–5
–60–40–20 0 20 40 60
10
–10
5
0
–5
–60–40–20 0 20 40 60
0.2
–0.2
0.1
0.0
–0.1
–60–40–20 0 20 40 60
φ = 60° φ = 120°←║ φ = 60° φ = 120°←║ φ = 60° φ = 120°←║ φ = 60° φ = 120°←║
AOS-I (550 nm)
view angle view angle view angle view angle
view angle
0 20 40 60 80
~1e-4
dI
~1e-4
dQ
view angle
0 20 40 60 80
~1e-4
dU
view angle
0 20 40 60 80
o Benchmarked >magnitude better
o Satisfies polarization accuracy
Polarization is an extremely useful tool to retrieve aerosol properties
GSFCJPLNRL
UCSDUMBC
RT comparison Studies
provided that the percent linear polarized light (“DLP”) is measured with high accuracies (0.2% - 0.5%)
our forward RT computations need to match these high accuracies in DLP !
dDLP (%)
UV sensitivity Studies
Motivation
Results
1) TOA polarized reflectance is more sensitive to variations in aerosol properties than in ocean
2) This leads to changes in the TOA degree of polarization >>0.3% that have unique spectral and angular patterns for perturbations in CDOM
Part II
UV Sensitivity Studies
Motivation
UV Sensitivity Studies
Reflection r = p I
S0 cosq0
60° 40° 20°
60° 60°
120°120°
q =
Azimuth angle
View angle
Sideward scattering
Backward scattering
Specular reflection
Sunglint region
Anti-solar point for q0
(i.e. backscattering direction)
j−j0 = 0°
180°
UV polarized reflected light is nearly insensitive to variations in the ocean color
But is this light sensitive to the amount and variations in aerosols?
rS0
TOA
SRF
385 nm
4 km
UV Sensitivity Studies
j−j0 = 180°
j−j0 = 0°
rocean (%) (385 nm)
3 3.5 4 4.5 5 7 12 5 13 13.56 ><
contribution of ocean to TOA reflectance: >13%
TOA
SRFrocean (%)
rocean, ,
P(%)
rocean ≡ rocean / r TOA (%)
Case I (open) ocean
Rayleigh scattering
Bodhaine et al. (1999)
Aerosol scattering
re = 0.15 μm, ve = 0.15, τ550 = 0.10
contribution of ocean to TOA polarized reflectance: <5%
average oligotrophic ocean
AOT(550) = 0.1, θ0 = 30°
Chow
dhary
et al. (2012)
4 km
RT results
385 nm
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
UV Sensitivity Studies
j−j0 = 180°
j−j0 = 0°
ΔrTOA (%) (385 nm)
0.5 1 1.5 2 2.5 3.5 4 5 6 93 ><
TOA
SRF
4 km
DrTOA (%)
DrTOA, ,
P(%)
DrTOA ≡ DrTOA / r TOA (%)
Case I (open) ocean
Rayleigh scattering
Bodhaine et al. (1999)
Aerosol scattering
re = 0.15 μm, ve = 0.15, τ550 = 0.10
max CDOM variation
AOT(550) = 0.1, θ0 = 10°
TOA polarized reflectance change: <2%
380 nm
Mediterranean
South Pacif ic
Chl [mg/m3]
DKbio = 0.2433
bio-optical model
Kd
≡ K
w+
Kbio
[1/m
]
More
l et al. (2007)
DKd ≈ 1.04(md)−1 (Da + bb)
CDOM
RT results
TOA reflectance change: ~7%
385 nm
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
UV Sensitivity Studies
j−j0 = 180°
j−j0 = 0°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
ΔrTOA (%) (385 nm)
0.5 1 1.5 2 2.5 3.5 4 5 6 73 ><
ΔrTOA (%) (385 nm)
0.5 1 1.5 2 2.5 3.5 4 5 6 73 ><
TOA
SRF
4 km
DrTOA (%)
DrTOA, ,
P(%)
DrTOA (%)
DrTOA, ,
P(%)
max CDOM variation
TOA polarized reflectance change: <2%
AOT(550) = 0.1, θ0 = 30°
RT results
TOA reflectance change: ~7%
385 nm
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
TOA polarized reflectance change: >7%
change aerosol zchange aerosol z
4 km
6 km
TOA
SRFDrTOA ≡ DrTOA / r TOA (%)
UV Sensitivity Studies
j−j0 = 180°
j−j0 = 0°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
ΔrTOA (x1000) (385 nm)
1 1.5 2 2.5 3 4 12 13 14 153.5 ><
ΔrTOA (x1000) (385 nm)
1 1.5 2 2.5 3 4 12 13 14 153.5 ><
TOA
SRF
4 km
DrTOA (abs)
DrTOA, ,
P(abs)
DrTOA (abs)
DrTOA, ,
P(abs)
max CDOM variation
TOA polarized reflectance change: <0.0015
AOT(550) = 0.1, θ0 = 30°
RT results
TOA reflectance change: ~0.01
385 nm
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
TOA polarized reflectance change: >0.005
change aerosol zchange aerosol z
4 km
6 km
TOA
SRFDrTOA ≡ DrTOA (absolute)
UV Sensitivity Studies
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
ΔrTOA (x1000) (385 nm)
1 1.5 2 2.5 3 4 12 13 14 153.5 ><
DrTOA (abs)
DrTOA, ,
P(abs)
RT results
TOA polarized reflectance change: >0.005
change aerosol zchange aerosol z
4 km
6 km
TOA
SRF
Δ DLP (%) (385 nm)
0.1 0.2.0.3 0.4 0.6 1.0 1.2 1.5 2.0 2.50.8 ><
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
D DLP ≡ D ( rTOA,P / rTOA )
“Polarization is an extremely useful tool to receive aerosol
properties provided that the percent linear polarized light
(DLP) is measured with high accuracies (0.2% - 0.5%)”
TOA DLP change: >1%
UV Sensitivity Studies
RT results
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ DLP (%)
0.05 0.12 .0.2 0.3 0.5 0.9 1.2 1.6 2.0 2.50.7 ><
λ = 355 nm λ = 385 nm λ = 415 nm λ = 445 nm
4 km
6 km
TOA
SRF
TOA
SRF
4 km
TOA DLP change: >1%
UV Sensitivity Studies
RT results
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ DLP (%)
0.05 0.12 .0.2 0.3 0.5 0.9 1.2 1.6 2.0 2.50.7 ><
λ = 355 nm λ = 385 nm λ = 415 nm λ = 412 nm
4 km
6 km
TOA
SRF
TOA
SRF
4 km
TOA DLP change: >1%
10 2 3 4 5 6
1
0
2
3
4
5
6
RSP: retrieved vs true height
Source: Wu et al. (In prep.)
UV Sensitivity Studies
RT results
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ DLP (%)
0.05 0.12 .0.2 0.3 0.5 0.9 1.2 1.6 2.0 2.50.7 ><
λ = 355 nm λ = 385 nm λ = 415 nm λ = 445 nm
TOA
SRF
4 km 4 km
TOA
SRF
Δ CDOM
TOA DLP change: >1%
UV Sensitivity Studies
RT results
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ Intensity (%)
0.5 1.0 1.5 2.0 2.5 3.5 4.0 5.0 6.0 9.03.0 ><
λ = 370 nm λ = 385 nm λ = 400 nm λ = 415 nm
TOA
SRF
4 km 4 km
TOA
SRF
Δ CDOM
TOA intensity change: 3%
Δ ω ω = 0.9 darker
brighter
UV Sensitivity Studies
RT results
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ DLP (%)
0.05 0.12 0.2 0.3 0.4 0.6 0.7 0.8 0.9 1.00.5 ><
λ = 370 nm λ = 385 nm λ = 400 nm λ = 415 nm
TOA
SRF
4 km 4 km
TOA
SRF
Δ CDOM
TOA intensity change: 0.7%
Δ ω ω = 0.9 darker
brighter
UV Sensitivity Studies
RT results
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ DLP (%)
0.05 0.12 0.2 0.3 0.4 0.6 0.7 0.8 0.9 1.00.5 ><
λ = 370 nm λ = 385 nm λ = 400 nm
TOA
SRF
4 km 4 km
TOA
SRF
Δ CDOM
TOA intensity change: 0.7%
Δ ω ω = 0.9 darker
brighter
absorbingaerosols
CDOM
phytoplankton
pigments
functional groups
particle sizes
physiology
pigment
fluorescence
coastal biology
atmosphericcorrection
(clear ocean)
atmosphericcorrection
(coastal ocean)
SW
IRN
IRV
isib
leU
ltra
vio
let
5 n
m r
eso
luti
on
(3
50
-885
nm
)
26
re
qu
ire
d “m
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isp
ectr
al” b
an
ds
3 S
WIR
ba
nd
s
products
UV Sensitivity Studies
RT results
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ DLP (%)
0.05 0.12 0.2 0.3 0.4 0.6 0.7 0.8 0.9 1.00.5 ><
λ = 385 nm λ = 400 nm
TOA
SRF
4 km 4 km
TOA
SRF
Δ CDOM
TOA intensity change: 0.7%
Δ ω ω = 0.9 darker
brighter
absorbingaerosols
CDOM
phytoplankton
pigments
functional groups
particle sizes
physiology
pigment
fluorescence
coastal biology
atmosphericcorrection
(clear ocean)
atmosphericcorrection
(coastal ocean)
SW
IRN
IRV
isib
leU
ltra
vio
let
5 n
m r
eso
luti
on
(3
50
-885
nm
)
26
re
qu
ire
d “m
ult
isp
ectr
al” b
an
ds
3 S
WIR
ba
nd
s
products
SPEX:
• Swath: 60 deg• Angular range: ±60 deg• # view angles: 5• Spectral range: 375-850 nm• Polarimetric accuracy: 0.2%• Radiometric accuracy: 2%
Source: O. Hasekamp (pers. com.)
RT Comparison studies 1) Accuracy for Stokes parameters I, Q, Uemerging from various AOS is better than 10–6
2) Corresponding accuracy in degree of linear polarization better than 0.1%
Conclusions
Part I
Part II
UV sensitivity Studies 1) TOA polarized reflectance is more sensitive to variations in aerosol properties than in ocean
2) This leads to changes in the TOA degree of polarization >>0.3% that have unique spectral and angular patterns for perturbations in CDOM
Backup Slides
RSP retrievals
RSP retrievals
Aerosol Layer Height Retrieval from RSP (synthetic)
radiance + polarization
Polarimetry in near UV: elevated aerosol layer ‘shields’ partly molecular (Rayleigh) scattering polarization measurements
provide aerosol height information.
Polarization measurements in blue / near-UV are needed. (This is for a homogeneous aerosol layer; for plumes MISR has shown
that stereo retrievals form multi-angle radiometry work well)
(Wu et al, in preparation)
only radiance
Aerosol Layer Height Retrieval from RSP (real measurements)
radiance + polarization
• Comparison between RSP and the Cloud Physics Lidar from the ER-2.
• Given the very different measurement approaches and definition of aerosol layer height, the agreement is very encouraging.
• The importance of blue / near-UV polarization measurements is also confirmed for real measurements.
only radiance
(Wu et al, in preparation)
RSP retrievals
Backup Slides
D-P hydrosol model
Reference
“We previously developed a hydrosol model for use in underwater light scattering computations.
We apply this model to measurements of total and polarized reflectance that were acquired over open ocean during the
MILAGRO campaign by the airborne Research Scanning Polarimeter (RSP). Analyses show that our hydrosol model
faithfully reproduces the water-leaving contributions to RSP reflectance.”
DP: Detritus-Plankton mixtures (used for PACE). FF: Fournier-Forand. OTHG: one-term Henyey-Greenstein. Red error bars : RSP data at 62 m above surface.
Detritus-Plankton hydrosol mixtures
Backup Slides
aerosol model variations
UV Sensitivity Studies
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ DLP (%)
0.05 0.12 .0.2 0.3 0.4 0.6 0.7 0.8 0.9 1.00.5 ><
λ = 355 nm λ = 385 nm λ = 415 nm λ = 445 nm
TOA
SRF
4 km
6 km
TOA
SRF
TOA DLP change: >0.3%
3 km
5 km
30°q0 =
UV Sensitivity Studies
Δ DLP (%)
0.05 0.12 .0.2 0.3 0.4 0.6 0.7 0.8 0.9 1.00.5 ><
λ = 355 nm λ = 385 nm λ = 415 nm λ = 445 nm
TOA
SRF
4 km
6 km
TOA
SRF
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
TOA DLP change: >0.7%
3 km
5 km
50°q0 =
UV Sensitivity Studies
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
60° 40° 20°
300° 60°
120°240°
q =
j−j0 = 0°
j−j0 = 180°
Δ DLP (%)
0.05 0.12 .0.2 0.3 0.5 0.9 1.2 1.6 2.0 2.50.7 ><
λ = 355 nm λ = 385 nm λ = 415 nm λ = 445 nm
TOA
SRF
4 km
Δ CDOM
4 km
6 km
TOA
SRF
TOA DLP change: >0.3%