Disequilibrium in the Ross of Mull Contact Metamorphic Aureole
VI-5475(SamCalValNotes) 1 SAM (Sun and Aureole Measurement) Calibration Prepared for MODIS/VIIRS...
Transcript of VI-5475(SamCalValNotes) 1 SAM (Sun and Aureole Measurement) Calibration Prepared for MODIS/VIIRS...
VI-5475(SamCalValNotes) 1
SAM (Sun and Aureole Measurement)
Calibration
Prepared for MODIS/VIIRS Science Team Meeting
Dennis Villanucci, Andrew LePage
John DeVore, A.T. Stair
January 2010
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Please open in “Notes” mode to see the notes.
VI-5475(SamCalValNotes) 2
1. Introduction
• SAM radiance measurements
- Solar disk and aureole profiles At 670 +/- 5 nm
- Lab calibration NIST traceable
- Field verification using AERONET for low ODs
- Radiometric accuracy: Disk radiance <1%, if OD<~0.6 Disk radiance <~10%, otherwise Aureole radiance ~15%
- Aureole profile precision (gradient): Pixel-to-Pixel Stnd Dev <0.5%
VI-5475(SamCalValNotes) 3
2. SAM Lab CalibrationNIST Standard Practice
Parameter Solar Disk Camera
Aureole Camera
Multiple Exposures: Duration
Relative to 40 ms standard
Relative to 40 ms standard
Radiometric (NIST Traceable Sphere (Absolute: 2%)
Absolute: <1% for ODs <~0.6
(AERONET ref); Otherwise <~10%
Absolute: ~15%
Flat-Field Not Needed See Panel 4
Linearity (Radiance)
See Panel 5 See Panel 5
Temperature Drift
-6ºC to 44ºC Not Needed
Internal
Scattering
Not Needed End-to-end, optics in place
Neutral
Density Filter
Independent Measurement
Not Applicable
Pixel Scale (deg/pixel)
Lab Measurement
Lab Measurement
VI-5475(SamCalValNotes) 4
3. SAM/AERONET Radiance Statistics
• RMS difference < 0.7% (~1000 values)
VI-5475(SamCalValNotes) 5
4. Flat Fielding (Aureole Camera)
Before FlatFielding
Af ter FlatFielding
NI ST Source Flat to 0.5%
Before FlatFielding
Af ter FlatFielding
NI ST Source Flat to 0.5%
VI-5475(SamCalValNotes) 6
5. Linearity (Typical Camera)
Polynomial: y = 6.615E-12 x3 - 1.348E-9 x2 + 1.633E-6 x1
0.0E+00
5.0E-05
1.0E-04
1.5E-04
2.0E-04
2.5E-04
3.0E-04
3.5E-04
4.0E-04
0 50 100 150 200 250
Pixel Value Above Bkgnd
Rad
ian
ce (
W/c
m2/s
r)
1000 ms
Linear
Poly. (1000 ms)
S/ N 300
Linearity of camera response with scene
brightness at one exposure and
temperature. Similar measurements
are made at other exposure durations, and
for each of the cameras used
in the SAM sensor.
VI-5475(SamCalValNotes) 7
6. Aureole FPA Trace Definitions
Up
Down
RightLef t
Average
Up
Down
RightLef t
Average
VI-5475(SamCalValNotes) 8
7. Typical Uniform Cloud Data Traces
• Demonstrates precision of profile
1.E-02
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0.01 0.1 1 10
Angle From Sun Center (deg)
Radia
nce
(W
/cm2/s
r/um
)
Average
Right
Lef t
Up
Down
SAM #300 - GSFC
17 J AN 09 ~ 18.5308 UT
I nstrumentalData Gap
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
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0.01 0.1 1 10
Angle From Sun Center (deg)
Radia
nce
(W
/cm2/s
r/um
)
Average
Right
Lef t
Up
Down
SAM #300 - GSFC
17 J AN 09 ~ 18.5308 UT
I nstrumentalData Gap
VI-5475(SamCalValNotes) 9
8. Radial Average, Std Dev of Traces
• Demonstrates precision of profile
1.E-02
1.E-01
1.E+00
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0.01 0.1 1 10
Angle From Sun Center (deg)
Rad
ian
ce (
W/c
m2/s
r/u
m)
Average
SAM #300 - GSFC
17 J AN 09 ~ 18.5308 UT
I nstrumentalData Gap
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
0.01 0.1 1 10
Angle From Sun Center (deg)
Rad
ian
ce (
W/c
m2/s
r/u
m)
Average
SAM #300 - GSFC
17 J AN 09 ~ 18.5308 UT
I nstrumentalData Gap
VI-5475(SamCalValNotes) 10
9. Non-uniform Cloud Example
1.E-02
1.E-01
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1.E+01
1.E+02
1.E+03
0.01 0.1 1 10
Angle From Sun Center (deg)
Radia
nce
(W
/cm2
/sr/
um
)
Average
Right
Lef t
Up
Down
SAM #300 - GSFC
17 J AN 09 ~ 18.5867 UT
I nstrumentalData Gap
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
0.01 0.1 1 10
Angle From Sun Center (deg)
Radia
nce
(W
/cm2
/sr/
um
)
Average
Right
Lef t
Up
Down
SAM #300 - GSFC
17 J AN 09 ~ 18.5867 UT
I nstrumentalData Gap
• Cloud non-unformity is detectable
VI-5475(SamCalValNotes) 11
10. Moderately Thick Cloud Example
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
0.01 0.1 1 10
Angle From Sun Center (deg)
Radia
nce
(W
/cm2
/sr/
um
)
Average
Right
Lef t
Up
Down
SAM #300 - GSFC
17 J AN 09 ~ 19.0753 UT
Solar Disk Camera
AureoleCamera
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
0.01 0.1 1 10
Angle From Sun Center (deg)
Radia
nce
(W
/cm2
/sr/
um
)
Average
Right
Lef t
Up
Down
SAM #300 - GSFC
17 J AN 09 ~ 19.0753 UT
Solar Disk Camera
AureoleCamera
• Demonstrates accuracy (2 cameras) and precision of profile (gradient)
VI-5475(SamCalValNotes) 12
11. Field Calibration Verification
• For absolute radiometric calibration of cameras; verified for solar disk radiance with thousands of measurements next to AERONET sensors
• For flat fielding of aureole pixel-to-pixel response, e.g. “gradient” correction; verified with hundreds of measurements of uniform clouds
VI-5475(SamCalValNotes) 13
SAM-AERONET Comparison
Quantity AERONET SAMScatterer Aerosols Clouds
(and aerosols)Size range (radius) ~ 0.1 – ~ 1
m~ 2.5 – ~ 25 m
OD range(high precision)
0 to ~ 1 0 to ~ 5 (ice)0 to ~ 10 (water)
Minimum aureole angle from disk edge
~ 2.25º ~ 0.25º
Measurement sampling
~ 10 min (typical)
~ 12 sec (adjustable)
Field of View or Regard
~ 120º(Scan FOR)
+/- ~ 8º (FOV)and ~ 6º to 50º
Pixel IFOV 1.2º 0.015º(1024 x 1280)
OD measurement accuracy (absolute)
0.01 to 0.02 < ~ 0.03
OD measurement precision (relative)
< 0.005 < 0.005
VI-5475(SamCalValNotes) 14
SAM Applications
• Climate (cloud) monitoring
• Cloud physics research
• Satellite algorithm cal/val
• Circumsolar radiation
Dennis Villanucci 781-272-1220 [email protected] LePage 781-272-1220 [email protected]
Contacts: