RADIOMETRIC CALIBRATION: STATUS. Sindy Sterckx, Stefan Adriaensen, Wouter Dierckx

Transcription

1 RADIOMETRIC CALIBRATION: STATUS Sindy Sterckx, Stefan Adriaensen, Wouter Dierckx

2 OUTLINE PROBA-V radiometric stability VNIR strips SWIR strips Dark current Reprocessing: changes to ICP files

3 PROBA-V INSTRUMENT STABILITY VNIR

4 INSTRUMENT STABILITY : BASED ON OSCAR DESERT METHOD LIBYA-4 BLUE Results OSCAR Libya-4 no A k updates considered LEFT CENTER RIGHT 4

5 INSTRUMENT STABILITY : BASED ON LIBYA4 BLUE Results OSCAR Libya-4 no A k updates considered LEFT CENTER RIGHT 5

6 INSTRUMENT STABILITY : BASED ON LIBYA4 BLUE Results OSCAR Libya-4 no A k updates considered LEFT CENTER %/year -0.46%/year RIGHT -0.51%/year 6

7 INSTRUMENT STABILITY : BASED ON LIBYA-4 RED Results OSCAR Libya-4 no A k updates considered LEFT CENTER RIGHT 7

8 INSTRUMENT STABILITY : BASED ON LIBYA4 RED Results OSCAR Libya-4 no A k updates considered LEFT CENTER -0.13%/year -0.08%/year RIGHT -0.24%/year 8

9 INSTRUMENT STABILITY : BASED ON LIBYA4 NIR Results OSCAR Libya-4 no A k updates considered LEFT CENTER RIGHT 9

10 INSTRUMENT STABILITY : BASED ON LIBYA4 NIR Results OSCAR Libya-4 no A k updates considered LEFT CENTER -0.85%/year -0.80%/year RIGHT -0.58%/year 10

11 SUMMARY TRENDS VNIR STRIPS OVER LIBYA-4 11

12 SUMMARY TRENDS VNIR : AVG OVER 16 DESERT SITES NOTE: surface characterisation based on POLDER/ATSR2 Govaerts & Clerici (2004) Larger absolute bias, but OK for trending MISR/MODIS for Libya-4 and Niger-2 Govaerts, Sterckx & Adriaensen (2013) 12

13 LUNAR CALIBRATION RESULTS: CENTER VNIR %/year +0.32%/year -0.12%/year Confirm relative stability of the VNIR strips responsivity 13

14 VNIR INTER-BAND

15 VERIFICATION OF INTER-BAND CALIBRATION ACCURACY OVER DCC 17

16 STABILITY OF INTERBAND DCC RESULTS 19

17 PROBA-V INSTRUMENT STABILITY SWIR

18 LEFT CAMERA SWIR STABILITY BASED ON OSCAR LIBYA-4 Results OSCAR Libya-4 no A k updates considered %/year -1.7 %/year %/year 21

19 CENTER CAMERA SWIR STABILITY BASED ON OSCAR LIBYA-4 Results OSCAR Libya-4 no A k updates considered %/year -1.4 %/year %/year 22

20 RIGHT CAMERA SWIR STABILITY BASED ON OSCAR LIBYA-4 Results OSCAR Libya-4 no A k updates considered %/year %/year %/year 23

21 SUMMARY TRENDS SWIR LIBYA-4 24

22 SUMMARY TRENDS SWIR 16 DESERTS 25

23 SWIR ICP ABSOLUTE CALIBRATION UPDATES date camera strip % change 20/12/2014 right swir /08/2015 right swir2 1 26/09/2015 left swir /09/2015 left swir /09/2015 left swir /09/2015 center swir /09/2015 center swir /09/2015 center swir /09/2015 right swir /09/2015 right swir

24 SWIR ICP ABSOLUTE CALIBRATION UPDATES (CON T) date camera strip % change 6/2/2016 LEFT swir /2/2016 LEFT swir /2/2016 LEFT swir /2/2016 CENTER swir /2/2016 CENTER swir /2/2016 CENTER swir /2/2016 RIGHT swir /2/2016 RIGHT swir /2/2016 RIGHT swir

25 DARK CURRENT

26 Dark cuurrent in DN at nominal IT Dark cuurrent in DN at nominal IT Dark cuurrent in DN at nominal IT Dark cuurrent in DN at nominal IT Dark cuurrent in DN at nominal IT Dark cuurrent in DN at nominal IT PIXEL DARK CURRENT VALUES AT NOMINAL IT AT REFERENCE TEMP -10 Dark cuurrent in DN at nominal IT LEFT SWIR Pixel CENTER SWIR 1 Dark cuurrent in DN at nominal IT RIGHT 50 SWIR RIGHT 19 SWIR RIGHT 0 SWIR LEFT SWIR Pixel Dark cuurrent in DN at nominal IT LEFT SWIR number of pixels with DC larger than thershold DC (at nominal IT) LEFT CENTER RIGHT 0 CENTER SWIR 2 Threshold 200 DC at nominal IT) SWIR 1 SWIR SWIR 3 SWIR 1 SWIR 2 SWIR SWIR 1 SWIR 2 SWIR Pixel Pixel Pixel Pixel CENTER SWIR Pixel Pixel Pixel

27 DARK CURRENT JUMPS (SOME EXAMPLES) => CAUSE OF VERTICAL STRIPES 30

28 REPROCESSING : RADIOMETRIC ICP FILE

29 REPROCESSING : SWIR ABSOLUTE CALIBRATION PARAMETERS Trending SWIR instead of stepwise updates (REPROCESSING vs OLD) LEFT SWIR Oct Mar Aug Jan Jun Nov Mar-16 CENTER SWIR Oct Mar Aug Jan Jun Nov Mar-16 RIGHT SWIR Oct Mar Aug Jan Jun Nov Mar-16 LEFT SWIR Oct Mar Aug Jan Jun Nov Mar-16 CENTER SWIR Oct Mar Aug Jan Jun Nov Mar-16 RIGHT SWIR Oct Mar-1409-Aug Jan Jun Nov-1531-Mar-16 LEFT SWIR Oct Mar Aug Jan Jun Nov Mar-16 CENTER SWIR Oct-1312-Mar-1409-Aug Jan Jun Nov-1531-Mar-16 RIGHT SWIR Oct Mar-1409-Aug Jan Jun Nov-1531-Mar-16

30 REPROCESSING : VNIR ABSOLUTE CALIBRATION PARAMETERS Bias (inter-camera //inter-band ) adjustments to be implemented from start of operations CENTER to LEFT camera CENTER to RIGHT camera Center BLUE :-1.8 % Center BLUE :-1.8 % Left BLUE : +1.1% Center RED : -2.1% Center RED : -2.1% RIGHT BLUE : +1.2% 35

31 DARK CURRENT Change in DC acquisitions/processing since 2015» Strong reductions Integration Time SWIR DC acquisitions from respectively 3s to 0.6s and later even to 0.2s» Why ICP? For files some for pixels reprocessing recorded DN of > data Risk acquired of nonlinearity/saturation before 2015 : effects at DN > 3300 ( << 4096) Dark current values of saturated pixels will be replaced with the value retrieved from the next closest dark current observation obt ained with low IT (were done before 2015 at irregular time intervals) All ICP files for reprocessing Dark current values ICP file will be based on DC acquisitions of the applicable month ( previous month) Bad pixels declared BAD at the start of the month» change 3s to 0.6s : for < 3 % pixels effect > 1 DN 37

32 EQUALISATIONS SWIR? IMPROVEMENTS UNFORMITY SWIR STRIPS see next ppt :Yaw manoeuvre analysis 38

33 43