Post on 26-Jun-2020
Optical TheoryBasics - 2
Atmospheric correctionsand parameter retrieval
Jose Moreno
3 September 2007, Lecture D1Lb2
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 2
OPTICAL THEORY-FUNDAMENTALS (2)
Radiation laws: definitions and nomenclatureSources of radiation in natural environment in the optical domainInteraction of radiation with matter in the optical domainIllumination and observation geometriesRadiative transfer in the optical domainGeneral solutions for the radiation transfer in the coupled earth-surface and through the atmosphereDerivation of surface reflectance from measured satellite radiancesSpectral information: signatures of natural objectsSpatial information: uniformity, textures and scalesTemporal information: land surface dynamics at multiple scalesInformation retrieval: from spectral indices to model inversionOverview of applications
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 3
Derivation of surfacereflectance from measured
satellite radiance
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 4
Pre-processing steps:- Radiometric calibration
- Noise removal
- Cloud screening
- Geometric correction
- Atmospheric correction
- Database management
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 5
• Pre-launch radiometric calibration to traceable standard (accepted reference)
• Post launch calibration campaigns to maintain/monitoring in flight calibration (vicarious)
• On-board calibration (both radiometric and spectral)
RADIOMETRIC CALIBRATION
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 6
CLOUD SCREENING
- Very dependent on the availablespectral information
- Many different algorithms (from simplethresholds up to sophisticate techniques)
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 7
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 8
SATELLITE SIGNAL MODELLING
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 9
•The atmosphere modifies theradiation measured by opticalsensors:• Aerosols and gases presentoptical activity at VIS/NIR/SWIR.• Reflectanceincreases/decreases dependingon the wavelength.• Image loses contrast.
Removing the atmospheric influence from remote sensing data is necessary before the data exploitation
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 10
• TOA radiance modeled assuming Lambertian reflectance for the target:
• Analytically invertible to retrieve ρs.
• Removal of adjacency effects
Surface reflectance retrieval
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 11
Non-Lambertian areas with topographic structure:- no analytic inversion under approximations- decoupling 'effective' reflectances and 'effective‘ geometric termsrequired for environment
- multistep numerical procedure required for inversion- multiple reflection terms only significant for high reflectance surroundings
Flat Lambertian areas:
INVERSION OF SURFACE REFLECTANCE
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 12
Atmospheric composition
Permanent Constituents Variable constituents
Constituent % byvolume
Constituent % by volume
Nitrogen (N2) 78.084 Water Vapor (H2O) 0.04Oxygen (O2) 20.948 Ozone (O3) 12 x 10-4
Argon (Ar) 0.934 Sulfur dioxide (SO2)b 0.001 x 10-4
Carbon dioxide (CO2) 0.033 Nitrogen dioxide (NO2) 0.001 x 10-4
Neon (Ne) 18.18 x 10-4 Ammonia (NH3) 0.001 x 10-4
Helium (He) 5.24 x 10-4 Nitric oxide (NO) 0.0005 x 10-4
Krypton (Kr) 1.14 x 10-4 Hydrogen sulfide (H2S) 0.00005 x 10-4
Xenon (Xe) 0.089 x 10-4 Nitric acid vapor traceHydrogen (H2) 0.5 x 10-4
Methane (CH4) 1.5 x 10-4
Nitrous Oxide (N2O) 0.27 x 10-4
Carbon Monoxide (CO) 0.19 x 10-4
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 13
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 14
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 15
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 16
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 17
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 18
110010009008007006005004000 .2
0 .4
0 .6
0 .8
1 .0
1 .2
1 .4
1 .6
dir ectglobal
wavelength (nm)
sola
r rad
iati
on(W
m
nm
)-1
-2
Relative Humidity (%)
0
5000
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15000
20000
25000
30000
35000
0 20 40 60 80 100RH (%)
Heig
ht (g
pm)
Temperature
0
5000
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25000
30000
35000
-80,0 -60,0 -40,0 -20,0 0,0 20,0 40,0Temperature (¼C)
Heig
ht (g
pm)
110010009008007006005004000 . 0
0 . 2
0 . 4
0 . 6
0 . 8
1 . 0
1 . 2
wavelength (nm)
Tota
l Opt
ical
Dep
th
Ozone
0
5000
10000
15000
20000
25000
30000
35000
0,00 2,00 4,00 6,00 8,00 10,00 12,00 14,00 16,00
Ozone (mPa)
Hei
ght (
gpm
)
In-situ radiosoundingsIn-situ spectral irradianceATMOSPHERIC INFORMATION
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 19
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 20
Surface reflectance retrievalAtmospheric correction: Removal of the atmospheric effectsfrom the measured at-sensor radiance, leading to thederivation of surface reflectance images.
AerosolsWater vapor
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 21
TOA BOA
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 22
+ =
µs DEMµil
Cosine correction
Hay’s model
Topographic effects
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 23
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 24
BRDF effects
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 25
Spectral information:signatures of natural objects
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 26
+90
0
-90400 2500wavelength (nm)
view zenith angle
wavelength (nm)
Hyperspectral BRDFSolar Principal Plane
C =0.0405 cmwaterview
zen
ith a
ngle
0.51
0.00
400
2500
-90
+90
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 27
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 28
SOIL REFLECTANCE
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 29
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.60
5
10
15
20
25
30
35
40
45
50
55
60
65
wavelength ( m)
refle
ctan
cegreen vegetation (alfalfa)senescent vegetation (barley)
μ
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 30
refle
ctan
ce
wavelength (nm)
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5
10
15
20
25
30
35
40
45
50
55
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
bare soilorganic litter (humic acid)
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 31
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 32
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 33
MERIS Landsat TM
HyMapCHRIS
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 34
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 35
Spatial information:uniformity, textures
and scales
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 36
SPATIAL SCALES TO BE RESOLVED 10 km toglobal
<1 - 300meters
Local site Global sampling
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 37
VIS/NIR/SWIR Colour Composite Thermal data
Multiresolution data
1.25 m
3.75 m
12.0 m
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 38
Spatialinformationin theimages
- Textures
- Higher orderstatistics
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 39
countingindividual trees by usingQuickbirdvery highresolutionimagery
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 40
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,30
0
0,32
5
0,35
0
0,37
5
0,40
0
0,42
5
0,45
0
0,47
5
0,50
0
0,52
5
0,55
0
0,57
5
0,60
0
0,62
5
0,65
0
0,67
5
0,70
0
0,72
5
0,75
0
0,77
5
0,80
0
0,82
5
0,85
0
0,87
5
0,90
0
0,92
5
0,95
0
0,97
5
1,00
0
1,02
5
1,05
0
1,07
5
1,10
0
PAN
BLUE
GREEN
RED
NIR
QuickBird
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 41
Temporal information:land surface dynamics
at multiple scales
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 42
> 3years
3 - 10days
Requires very large time series
TIME SCALES TO BE RESOLVED
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 43
Time series: Coupling canopyfunctioning and radiative transfermodels for remote sensing data assimilation
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 44
MERIS - 14 July 2003 Landsat - 15 July 2003
MERIS and Landsat both provide time series at different spatial and temporal scales
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 45
Stable calibration,adequate cloud screeningand precise atmosphericcorrections are needed fortime series analisis
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 46
Information retrieval:from spectral indices
to model inversion
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 47
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 48
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 49
MERIS Terrestrial Chlorophyll Index (MTCI)
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 50
Retrievals from hyperspectral data:
Canopy watery = 3,1431x + 857,
R2 = 0,5797
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
-100 0 100 200 300 400 500 600 700 800 900
Index
Corn bar1_12Subarbeet_bar1_12Barley bar1_12Wheat_bar1_12Alfalfa bar_1_12Corn bar2_12Sugarbeet bar2_12Barley bar2_12wheat bar2_12Alfalfa bar2_12Sugarbeet bar1_9Alfalfa bar1_9Sugarbeet bar2_9Alfalfa bar2_9Sugarbeet bar1_15Alfalfa bar1_15Subarbeet bar2_15Alfalfa bar2_15
y = 0,0359x + 0,347R2 = 0,3789
0
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35
40
45
-100 0 100 200 300 400 500 600 700 800 900
Index
Corn bar1_12Sugarbeet bar1_1Barley bar1_12Wheat bar1_12Alfalfa bar1_12Corn bar2_12Sugarbeet bar2_1Barley bar2_12Wheat bar2_12Alfalfa bar2_12Sugarbeet bar1_9Alfalfa bar1_9Sugarbeet bar2_9Alfalfa bar2_9Sugarbeet bar1_1Alfalfa bar1_15Sugarbeet bar2_1Alfalfa bar2_15
Leaf chlorophyllLeaf chlorophyll
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 51
Verhoef and Bach, 2007
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 52
• turbid medium• separation green / senescent parts: LAIT = LAIG + LAIS
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 53
Choice of the merit function
Incorporation of the uncertainties in the inverse process:
[ ] [ ] [ ] [ ]ptpCRMmes
t
CRMmes VVCVVVRRWVRR −−+−−= −− 112 )()(χ
The maximum likelihood on the variables minimize:
Residuals
a prioriCovariance Matrix
Residuals
a prioriCovariance Matrix
Radiometric Part Variable Part2)(∑ ⎥⎦⎤
⎢⎣⎡ −M
iiR
iCRM
imes VRRσ
2
∑ ⎥⎦⎤
⎢⎣⎡ −N
jiV
ipi VVσif diagonal matrixes
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 54
Neuralnetworkmethods
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 55
Spectral-angular synergy:
application of synergy
0
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65
70
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
0
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45
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600
SUGAR BEET
wavelength (nm)
wavelength (nm)
refle
ctan
cere
flect
ance
ALFALFA
Li ne 1 , n oo nLi ne 2 , n oo nLi ne 1 , mo rn in gLi ne 2 , mo rn in gLi ne 1 , a f t e rn oo nLi ne 2 , a f t e rn oo n
SV6 - C03 UTM-X: 577783 UTM-Y: 4324794 LAI = 1.71 fCover = 0.61
Li ne 1 , n oo nLi ne 2 , n oo nLi ne 1 , mo rn in gLi ne 2 , mo rn in gLi ne 1 , a f t e rn oo nLi ne 2 , a f t e rn oo n
V16 - C01 UTM-X: 577550 UTM-Y: 4324069 LAI = 1.84 fCover = 0.95
Homogeneous vegetation:Spectral information dominant
Heterogeneous vegetation:Angular information dominant
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 56
Overview of applications
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 57
- Mapping Applications - cartography - thematic mapping - Monitoring Applications - ecosystems dynamics - natural hazards (fires, floods, desertification) - Research about Land Surface Processes - heat and mass exchange at Land/Atmosphere interface - photosynthesis and net primary production - hydrologic processes - Land/Atmosphere exchange of biochemicals
REMOTE SENSING OF LAND SURFACE PROCESSES
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 58
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 59
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 60
3 September 2007 D1Lb2 Atmospheric corrections and parameter retrievals Jose Moreno 61
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