CALCON Landsat-8 OLI: On-Orbit Spatial Uniformity, Absolute Calibration and Stability

Transcription

1 CALCON 2013 Landsat-8 OLI: On-Orbit Spatial Uniformity, Absolute Calibration and Stability D. Helder F. Pesta J. Brinkmann L. Leigh D. Aaron --South Dakota State University Brian Markham Julia Barsi --NASA Goddard Space Flight Center Ron Morfitt Esad Micijevic --USGS EROS Jeff Czapla-Myers --University of Arizona 1

2 Outline On-orbit spatial uniformity Side-slither Lifetime statistics Absolute radiometric calibration PICS Vicarious Temporal Stability Diffuser Stim Lamps Acknowledgement: SDSU s contribution was supported by the NASA Landsat Project Science Office and USGS EROS. 2

3 OLI On-Orbit Spatial Stability: Side Slither Maneuver 3

4 FPA Projection Effect Side Slither 4

5 SS uncertainties vs. FPM Position FPM 1 FPM 2 FPM 13 FPM Side-Slither Temporal Analysis - Band 1 FPM 1 Det. 1 Classic SMA Total Side-Slither Temporal Analysis - Band 1 FPM 2 Det. 103 Classic SMA Total Side-Slither Temporal Analysis - Band 1 FPM 13 Det. 402 Classic SMA Total Side-Slither Temporal Analysis - Band 1 FPM 14 Det. 490 Classic SMA Total Relative Gain Relative Gain Relative Gain Relative Gain / / / /2013 Date of Collect / / / /2013 Date of Collect / / / /2013 Date of Collect / / / /2 Date of Collect Notes: 1. Plots show one representative detector rel gain across focal plane; grid division = All vertical axes at same scale. 3. Error bars indicate standard deviation of measurement at each site. Relative Gain Side-Slither Temporal Analysis - Band 1 FPM 7 Det. 203 Classic SMA Total / / / /2013 Date of Collect 1 FPM 7 FPM Relative Gain Side-Slither Temporal Analysis - Band 1 FPM 8 Det. 303 Classic SMA Total / / / /2013 Date of Collect Notes: 1. Center FPMs indicate a sweet spot. --increased interaction between SS maneuver and site variability. --likely due to FPM alignment during SS maneuver. 2. Some indication of differences between desert and snow/ice sites --FPM 7 is an example 5

6 Relative Gain Analysis Greenland, Band 1 FPM 1 Default CPF Gains Streaking Metric S i = L i 1/2 L i 1 + L i+1 /L Libya SS Gains 6

7 OLI On-Orbit Spatial Stability: Relative Gains via Lifetime Statistics 7

8 Data Available Over a sufficiently large sample of orbits, the Earth can be treated as a pseudo-random process. Averaging pixel response should show residual pixel differences to uniform illumination USGS Earth Resources Observation and Science (EROS) stores linearized, background subtracted histogram statistics into their Trending Database These are Digital Counts before any absolute or relative gain correction is applied Relative gain estimation works best across scenes with both high scene mean high standard deviation Greenland Mali Ocean 8

9 Sahara Work Around 175/40 The Sahara Desert has high values in many bands, so it is a sample of the Global Distribution Using the average of 480 Available Scenes to find the average pixel column stats for each band 205/50 Then using the classic histogram method relative gains were calculation with FOV as reference RG i = L i L These relative gains were tested on a uniform scene over ice in Greenland 9

10 Coastal Aerosol (Band 1) 'LC LGN01': 'Greenland Ice' Default Histogram Stats 10

11 Coastal Aerosol (Band 1) 'LC LGN01': 'Greenland Ice' Default 11

12 Histogram Stats Coastal Aerosol (Band 1) 'LC LGN01': 'Greenland Ice' 12

13 Striping Coastal Aerosol (Band 1) The streaking metric was reduced dramatically in Band 1 Greenland S i = L i 1/2 L i 1 + L i+1 /L Current (Pre-launch) Histogram Relative Gains Mali Ocean 13

14 OLI ABSOLUTE CALIBRATION: PICS 14

15 OLI On-Orbit Calibration: PICS Absolute Cal Model Calibrated detector-based approach using Terra MODIS Spectral information based on Hyperion The absolute calibration model is of the form ρ LLLLL 4 λ, SSS, VVV = K λ ρ h λ f A (t) [1 SSS 33 m 1 λ VVV λ m 2 λ VVV 2 m 3 λ ] Where, K = scaling factor, ρ h = spectral content of the scene obtained using Hyperion f A (t) = atmospheric model The BRDF coefficients for view zenith angle were derived using Terra MODIS and was scaled to 30 degrees solar zenith angle The BRDF coefficients for view zenith angle were derived using Hyperion measurements (± 18 deg) 15/39

16 Landsat 8 Trending Over Libya 4 6 Collects over Libya 4 starting from April 16. Clouds were visible in 2 images along the South-East Region Trended with smaller ROIs to avoid cloud ~ 60 km x 40 km 16/39

17 OLI Calibration Results over Libya 4 In general, all the bands are within 3%. Higher Differences in Blue, Green and SWIR. Random uncertainty is within 1.5% and systematic uncertainty is within 3% for all bands. 17/39

18 ON ORBIT ABSOLUTE CALIBRATION: UNIV. OF ARIZONA Jeff Czapla-Myers 18

19 SUMMARY OF UNIV. OF ARIZONA WORK FROM DSL (18 MAR 11 MAY 2013) Number of days in field: 29 Field campaigns: 8 Field sites: 5 Landsat 8 OLI attempts: 11 Successful collects: 6 (2 during tandem flight with Landsat 7) Miles driven: ~

20 CALCON 2013 COLLECTION SITES Alkali Lake, NV (P41) 2. Railroad Valley, NV (P40) 3. Ivanpah Playa, CA (P39) 4. Red Lake Playa, AZ (P38 & P39) 5. McLaws Playa, AZ (P36)

21 Alkali Lake RRV Ivanpah Red Lake 21

22 SUMMARY OF ALL BANDS 6 successful Univ. of Arizona field collections 4 different sites in Arizona, California, and Nevada (Alkali Lake, NV clouded over) Uncertainty bars are 1-sigma standard deviation of the results TOA Spectral Radiance TOA Reflectance 22

23 23

24 OLI STABILITY: Lifetime Response Trends 24

25 Diamonds = Stim Lamps Squares = Diffuser 0.6% 25

26 VNIR Band Stability Blue Band 2: Δ = -0.2% Green Band 3: Δ 0.2% Red Band 4: Δ = +0.2% NIR Band 5: Δ = +0.1% 26

27 SWIR, Pan, & Cirrus Band Stability SWIR 1 Band 6: Δ 0.2% SWIR 2 Band 7: Δ 0.2% Pan Band 8: Δ = 0.2% Cirrus Band 9: Δ 0.2% 27

28 Summary & Conclusions On-orbit Spatial Uniformity Very uniform sensor, difficult to find scenes with stripes; coastal aerosol band worst offender Side-slither and lifetime statistics methods are effective in removing striping to streaking metric < 0.2% Vicarious Absolute Calibration: Reflectance-based PICS-based abs cal shows 3% deviation in Coastal aerosol while hovering around 1% in other bands Vicarious approach shows 5% and 4% in Coastal Aerosol and Blue bands and under 3% in the rest Vicarious Absolute Calibration: Radiance-based Initial results indicate within 5% requirement On-Orbit Temporal Stability Very stable instrument in all bands with stim lamps and diffuser in good agreement; no long term degradation apparent. Worst case stability in Coastal Aerosol band with degradation of 0.6% since launch, all other bands at 0.2% 28