1. Radiometric Consistency between AVHRR, MODIS, and VIIRS in SST Bands
- MICROS update since -
Radiometric Consistency between AVHRR, MODIS, and VIIRS in SST Bands
Xingming Liang1,2, Sasha Ignatov1, and Korak Saha1,2
1NOAA/NESDIS/STAR, 2CSU/CIRA
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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2. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Acknowledgments
Advanced Clear-Sky Processor for Oceans (ACSPO; NESDIS SST System): Sensor Radiances over Oceans with Clear-Sky Mask and QC
J. Sapper, Y. Kihai, B. Petrenko, J. Stroup, P. Dash, F. Xu, M. Bouali, X. Zhou – NESDIS SST Team
Community Radiative Transfer Model (CRTM) implemented in ACSPO
F. Weng, Y. Chen, P. Van Delst, Q. Liu, D. Groff, E. Borbas, C. Mueller – CRTM Team
AVHRR, MODIS, VIIRS Characterization & Cross-platform Consistency, including Double Differences (DD) for Global Space-based Inter-Calibration System (GSICS)
F. Wu, F. Yu, L. Wang, F. Weng, C. Cao, J. Xiong, M. Goldberg, T. Hewison, X. Hu, T. Chang – GSICS Team
Simon Hook – NASA/JPL
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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3. Content – Progress since 2012
SNPP VIIRS, Terra/Aqua MODIS, Metop-B AVHRR added in MICROS
Reconciled MODIS with AVHRR and VIIRS sensors
Update on MICROS Double Differences
Conclusion & Future Work
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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4. VIIRS S-NPP, MODIS Terra & Aqua and AVHRR Metop-B added in MICROS
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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5. Background & Objectives
S-NPP Launched 28 October 2011
Bridge mission between POES/EOS and JPSS
US contribution: S-NPP, J1 (2016) and J2 (2021): Afternoon orbit (1:30 pm)
EUMETSAT contribution: Metop-A (2006), -B (2012), -C (2017): Morning orbit (10:30 am)
Sensors: POES/Metop: AVHRR; EOS: MODIS; S-NPP/JPSS: VIIRS
NESDIS is responsible for S-NPP/JPSS radiances (Sensor Data Records, SDR) and derived products (EDR), including SST
SNPP Launch
Stability and cross-platform consistency of VIIRS, MODIS, and AVHRR BTs is critical to ensure stability and continuity of POES, EOS and JPSS SST products
Metop-B Launch
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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6. Platforms/Sensors updated in MICROS
Several AVHRRs analyzed in
Metop-A (FRAC-1km and GAC-4km) – Stable
NOAA19 (GAC) – Stable
NOAA18 (GAC) – Somewhat unstable
NOAA17 (GAC) – Scan Motor Stalled in Feb’2010
NOAA16 (GAC) – Out of family, likely subject to Cal issues
Added in Jan’2012
NPP/VIIRS (0.75km) - Stable
Terra/MODIS (1km) - Stable
Aqua/MODIS (1km) - Stable
Added in Sep’ 2012
Metop-B (FRAC-1km and GAC-4km) – Stable
In pipeline
Geo sensors: MSG/SEVIRI, GOES-R/ABI
Leo sensors: ERS/(A)ATSR
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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7. SST Bands for different sensor
IR37
IR11
IR12
Optional
AVHRR
Ch3B (3.7 µm)
Ch4 (11.3 µm)
Ch5 (12.0 µm)
N/A
MODIS
Ch20 (3.79 µm)
Ch31(11.02 µm)
Ch32 (12.03 µm)
Ch22 (3.96 µm)
Ch23 (4.06 µm)
Ch29 (8.52 µm)
VIIRS
M12 (3.70 µm)
M15 (10.76 µm)
M16 (12.01 µm)
M13 (4.05 µm)
M14 (8.55 µm)
SEVIRI (planned)
Ch4 (3.90 µm)
Ch9 (10.8 µm)
Ch10(12.0 µm)
Ch7 (8.7 µm)
ABI (planned)
Ch7(3.90 µm)
Ch14 (11.2 µm)
Ch15(12.3 µm)
Ch11 (8.5 µm)
Ch13 (10.35 µm)
Only clear-sky ocean 3.7, 11 and 12 µm for AVHRR, MODIS and VIIRS are currently monitored in MICROS
Adding optional bands is underway
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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8. MICROS Data Availability (June 2012 – on)
Data Availability added in MICROS to monitor ACSPO real-time data processing status
ACSPO processing becomes stable after Sep. 2012
Data Gap from Jun-Aug 2012 is due to STAR move to NCWCP
All gaps have been filled after L1B data became available and network stabilized
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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9. Global Daily Maps from SNPP VIIRS, Terra/Aqua MODIS, Metop-B AVHRR
Consistent with analyses, global distributions are uniform & the M-O biases close to 0
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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10. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Global Histograms
AVHRR GAC
High Resolution
3.7 µm
3.7 µm
More clear-sky pixels generated from high res. sensors, especially VIIRS (~100 Mln/Night)
Similar to AVHRR, MODIS&VIIRS shapes are close to Gaussian. M-O bias is slightly positive.
4 AVHRRs (Metop-A, NOAA-16, -18 and -19), VIIRS, Terra MODIS consistent to within ~0.1 K
Terra and Aqua inconsistency: ~0.3 K
Metop-A and -B inconsistency: ~0.15 K
Cross-platform inconsistencies may be due to
Overpass times from 9:30pm-5am – M-O Biases subject to Diurnal Effects
Errors in sensor calibrations
Errors due to real spectral response differences, or inconsistent CRTM coefficients
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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11. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Time Series of M-O Bias
Consistently with AVHRRs, MODIS & VIIRS also show warm M-O biases
All AVHRRs, MODISs and VIIRS are generally stable, except for NOAA-16
M-O biases systematically differ between Metop-A and -B, and Terra and Aqua
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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12. with AVHRR and VIIRS sensors
MODIS reconciled
with AVHRR and VIIRS sensors
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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13. MODIS was initially out-of family in MICROS5
Three MODIS anomalies were initially observed, after MODIS was added in MICROS:
IR37 (Ch20): Terra - Aqua systematically differ by ~0.3 K
IR11 (Ch31): Terra – Aqua consistent, but both are out of AVHRR&VIIRS cluster by ~+0.55K
IR12 (Ch32): Terra – Aqua consistent, but both are out of AVHRR&VIIRS cluster by ~+0.30K
Joint analyses between SST, CRTM, and MODIS sensor calibration Team has shown:
Anomalies in IR11 and IR12 bands are due to suboptimal CRTM coefficients used in CRTM V2.02
For IR37, the Terra-Aqua cross-platform bias is mainly due to MODIS calibration
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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14. MODIS brought in family in MICROS V6
Based on MICROS feedback, CRTM Team updated coefficients in CRTM V2.1. SST Team immediately implemented in MICROS V6
MODIS IR11 and IR12 are back in AVHRR & VIIRS family
MODIS IR37 are shifted by ~-0.1 K for both Terra and Aqua,
But inconsistency between Terra and Aqua in IR37 persists at ~0.3 K
Suggests that it is due to MODIS calibration issue
Work is underway with MODIS calibration support Team to resolve
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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15. Update of MICROS Double Differences
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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16. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Nighttime µm
(Ref=Metop-A GAC)
VIIRS recalibration
CRTM V2.1 implemented
N16: unstable and out of family
All AVHRRs, Terra/MODIS, and NPP/VIIRS are consistent to within ±0.1K
VIIRS Cal Change 7 Mar 2012 reset by +0.14K; Remains in-family
Terra was in AVHRR/VIIRS family, but Aqua was biased by ~0.3 K when CRTM V2.02 used.
They were shifted by and K when CRTM V2.1 was implemented on Sep. 13, 2012.
Metop-A and –B are inconsistent by ~0.17 K, partly due to suboptimal coefficients used in CRTM V2.1.
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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17. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Nighttime µm
(Ref=Metop-A GAC)
CRTM V2.1 implemented
N16: unstable and out of family
VIIRS recalibration
Metop-B: out of family
All AVHRRs and NPP/VIIRS are consistent to within ±0.1K
VIIRS Cal change 7 Mar 2012 reset by +0.14K – now better in family
Terra and Aqua/MODIS out of family by 0.6K – due to suboptimal CRTM coefficients in V2.02
Both were back in family after CRTM V2.1 implemented on Sep. 13, 2012
Metop-A and –B are inconsistent by ~0.3 K, due to suboptimal CRTM coefficients used in CRTM V2.1.
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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18. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Nighttime µm
(Ref=Metop-A GAC)
CRTM V2.1 implemented
VIIRS recalibration
N16: unstable and out of family
All AVHRRs and NPP/VIIRS are consistent to within ±0.1K
VIIRS Cal Change 7 Mar 2012 reset +0.14K – now better in family
Terra and Aqua/MODIS out of family by 0.3K – due to suboptimal CRTM coefficients in V2.02
Both were back in family after CRTM V2.1 implemented on Sep. 13, 2012
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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19. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Nighttime DD’s SST
(Ref=Metop-A GAC)
CRTM V2.1 implemented
New Reg. Coeff. used
VIIRS recalibration
N16: unstable and out of family
All AVHRRs, MODISs and NPP/VIIRS SSTs are consistent to within ±0.1K
VIIRS Cal Change 7 Mar 2012: SST +0.10K – Out of family
New SST coefficients implemented 3 May 2012: SST -0.15K – Back in family
CRTM update resulted regression SSTs more noise, and the new coefficients have been implemented since Dec More data is needed to understand their performance.
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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20. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Conclusion
MODIS Terra & Aqua, VIIRS S-NPP, and AVHRR Metop-B added in MICROS
All new platforms proved stable from Jan 2012 – present
M-O statistics for new platforms are comparable with early AVHRRs in MICROS
Data Availability is developed to monitor ACSPO real-time data processing status
MODIS BTs were biased warm wrt AVHRRs & VIIRS by K , due to incorrect CRTM coefficients in CRTM V2.02, and fixed in CRTM V2.1
Terra-Aqua MODIS inconsistency in 3.7 µm ~0.3K remains - Calibration revision needed
Update of MICROS Double Differences
AVHRRs, MODISs and NPP/VIIRS BTs are consistent to within ±0.1K, except for NOAA-16, Metop-B, and Aqua
VIIRS BTs closer in-family, following CAL update on 7 March 2012
Metop-A and –B inconsistent to ~0.3 K, partly due to suboptimal CRTM coefficients
Consistent CRTM coefficients are critical for Double Differences. Work with CRTM Team is underway to establish version control
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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21. Ongoing and Future Work
Add New Sensors in MICROS
MSG/SEVIRI (in progress), GOES-R/ABI
ERS/(A)ATSR
Improve Accuracy of MICROS DDs
Use more accurate first guess fields – SST# and Profiles
Improve ACSPO cloud mask
Improve CRTM consistency and accuracy (especially affects daytime)
# Saha, K., A. Ignatov, X. M. Liang, and P. Dash (2012), Selecting a first-guess sea surface temperature field as input to forward radiative transfer models, J. Geophys. Res., 117, C12001, doi: /2012JC008384
Understand and Minimize Cross-platform Biases
Model diurnal variation (DV) in first-guess SST input to CRTM
Improve Sensor Radiances (Calibration, Spectral Response Functions)
Extend MICROS to Include Reflectance Bands
Use GOCART and NAAPS 3D aerosol fields inputs into CRTM, evaluate “M”
Evaluate M-O biases and DDs
Aerosol Quality Monitor (AQUAM: was set up to prepare for adding aerosol in CRTM
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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22. GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
Thank you!
GSICS Annual Meeting, March 4-8, 2013, Williamsburg, VA
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