1. V: Instrument & Product Calibration / Validation
Alexander P. Trishchenko* (Environment Canada) Fuzhong Weng (NOAA)
* on secondment from the Canada Centre for Remote Sensing, NRCan

2. Outline EC PCW CalVal Plan STAR CalVal Overview
Calibration requirements for PCW imager vs GOES-R ABI
Planned instrument calibration approach for PCW
Inter-calibration with GEO and LEO, participation in GSICS
STAR CalVal Overview
IJPS Calibration
GOES/GOES-R
NPP/JPSS
Non-NOAA (FY-3/DMSP/NASA/Jason)
GSICS

3. PCW Imager Vs GOES-R/ABI
Subgroup
Wavelength (microns)
S/N, NEDT or NEDR
Calibration Accuracy
Geometric Accuracy (GA)
Dynamic Range 1
VNIR
PCW
bright signal level
(100% albedo SZA=300)
ABI
1:300 at 100% albedo
Solar bands: 5%
IR bands: 0.5K
Solar bands: <4%
IR-bands:
PCW (1-s)
Absolute GA error <0.35 of Angular Sampling Distance (ASD)
Band-to-band co-registration error
<0.3 ASD
ABI (3-s)
Absolute navigation errors 21 to 32 mrad depending on sun eclipse
Band-to-band co-registration error <6.4mrad
% albedo
Linearity range (dim to bright)
Bright: SZA=300, 100% albedo
Dim: SZA=800,1% albedo 2 3 4 5
SWIR 6 7 8 9
MWIR
PCW: [mW/m2/sr/cm-1]
ABI: [mW/m2/sr/cm-1]
4K-410K
4K-400K 10
4K-335K
(4K-300K for Ch.10, 11, >13mm)
4K-300K (Ch.10-11,14)
4K-330K (Ch.13,15-17)
4K-320K(Ch.12)
4K-305K(Ch.18) 11 12 13
LWIR 14 15 16 17 18
LIRCO2
4K-300K 19 20 21
Bands in Bold are Priority 1. The remaining bands are in priority 2 list

4. Calibration for PCW Pre-launch characterization In-flight calibration
Some limited capacity exist in Canada (ABB BOMEM, COMDEV, CSA DFL)
Co-operation with NOAA, NASA and NIST would be very helpful for pre-launch radiometric, geometric and spectral calibration of PCW imager
In-flight calibration
Solar, spectralon diffusor(s): frequent in the beginning, periodic during regular operations (limited by spectralon UV exposure)
Blackbody, every scene
Deep space counts (twice per scan)
Intercalibration between PCW imagers to ensure consistency in derived imagery and products
Lunar calibration – co-operation with NOAA and NASA would be very helpful
NOAA bias analysis using comparison with RTM results would be very useful

5. Intercalibration with LEO and GEO
PCW would significantly benefit from participation in the Global Space-based Inter-Calibration System (GSICS)
Improved quality of PCW imagery and products
Consistency between PCW and other satellite data
PCW can be intercalibrated against polar orbiters (LEO) as well as GEO
The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission led by NASA could be of a unique value for absolute radiometric and spectral calibration

6. Temporal coverage map for PCW system
(% of total time, 100% means 24hrs per day)
VZA <700;
100% coverage >580N;
~ 50% for tropics;
Up to 20% for tropical zone below equator
Good opportunity for temporal and spatial collocation
Trishchenko and Garand, 2010, JTECH, submitted

7. Imagery and Product Cal/Val
Part of the PCW Meteorological Product Application Processing Facility (MAPF) at EC.
L1 QC
Calibration monitoring
Geolocation monitoring
Operational product verification
Operational analysis and reporting statistics
Visual control
Cal/Val activities could be shared with NOAA
Science activities
Focused research in special areas of interest & products
Specialized product cal/val projects involving joint science teams
Partnering with CEOS WGCV and GSICS

8. NESDIS/STAR Operational Calibration
IJPS (NOAA/METOP) Calibration
TVAC analysis
Radiometric calibration
Calibration coefficients LUT and data sets
Spectral and spatial calibration
On-orbit verification and Long-term monitoring
GOES-R Calibration Working Group
Post-launch checkup
Vicarious calibration
NPP/JPSS Calibration
SDR Code processing and updates
On-orbit Verification
Long-term monitoring
Non-NOAA Instruments (FY-3/DMSP/GPM)
WMO GSICS Executive Chair and Coordination Center

9. The GOES-R Calibration Working Group Led by Dr. C. Cao
Verify and ensure well-calibrated, & well-navigated GOES-R L1b data for the life time of the instruments (ABI, GLM, and SWx)
Ensure Level 1B data quality. Provide technical oversight and IV&V for:
Radiometric calibration
Spectral calibration
Spatial calibration/navigation check
Independent verification of L1B data
Evaluate and mitigate instrument performance risks (e.g., possible striping, noise, cross-talk, RVS, spectral response uncertainty, etc)
Provide technical support to the Flight and Ground through PSE
Radiometric
Spectral
Spatial

10. The GOES-R Calibration Working Group Expertise
Prelaunch calibration support (flight segment)
Test data analysis and instrument performance evaluation (bench and thermal vacuum)
Prelaunch test participation on-site at Rochester and Fort Wayne (w/ two CWG representatives)
SI traceability using NIST state-of-the-art technologies such as transfer radiometers (TXR, VXR) as well as SIRCUS characterization
Expertise include advanced degrees in opto-electronics, physics, imaging science, software engineering, and Earth sciences.
Advisors from heritage GOES, POES, and NASA EOS programs
Members from NOAA, NASA, NIST, and MIT/LL
Ground systems
Calibration support to the operational processing system design and development
Postlaunch capability developments
On-orbit verification
Instrument performance evaluation
Anomaly diagnosis
Vicarious calibration
Operational longterm monitoring
Prototyping for GOES-R using current GOES data
GSICS collaboration
From Meteorology
to Metrology

11. Four Phases of Calibration/Validation
1. Pre-Launch (development and I&T)
- CDRL peer review, PDR/CDR
- Algorithm & calibration database development
& verification
- Data format/content/quality flags
- Bench/TVAC tests and analysis
- Trade studies and waivers
- Validation capability development and preparation
- Prelaunch SI traceability
2. Operational check-out (Post-Launch Tests)
- Engineering tests to ensure specification compliance
- Calibration processing
- Anomaly analysis
3. On-orbit verification (Environmental cal. initialization)
- Instrument characterization
- Sensor artifact study and correction
- Algorithm adjustment
- Inter-comparison between satellites, and with NWP
models
- Both SDR and EDR Validation
4. Long-Term Monitoring (Mission operational life)
-Routine monitoring of instrument performance
-Inter-satellite comparison and NWP models
- Efforts focused to maximize pre-launch Cal/Val activities in preparation for
on-orbit instrument calibration

12. Spectral Response Function Analysis
Two sets of pre-launch spectral response functions (SRFs) for ABI
The CIMSS version and the CWG version
Quantified the differences between them and their impacts through spectral analysis using Hyperion and IASI spectra
Working with AWG to assess impact (Walter Wolfe & Jamie Daniels)
Hyperion Derived (VNIR) Targets
IASI Derived (IR) Targets
Developing a set of tools to characterize, evaluate and analyze spectral instruments sensing in the visible through infrared

13. Spectral Response Function Analysis
Differences found between the two sets of SRFs
Solar Bands: differences ranged from near 0 to approaching 2% TOA reflectance
IR Bands: differences from near 0 to >1K in brightness temperature
Recommendation: users should use a consistent set of SRF, until the flight model SRF becomes available
VNIR Results
IR Results
Developing a set of tools to characterize, evaluate and analyze spectral instruments sensing in the visible through infrared

14. NIST Activities
Working with NIST and ITT on the deployment of NIST instruments
VXR: ~ Spring 2011
TXR: ~ 2010
SIRCUS: in discussion with ITT
Thermal Transfer Radiometer (TXR), Visible Transfer Radiometer (VXR), and ASD Spectrometer
Ensure prelaunch SI traceability
Spectral Irradiance and Radiance Responsivity
Calibrations using Uniform Sources (SIRCUS)
Significantly improves solar band spectral response
function characterization/validation
Straylight characterization
Capabilities for IR channels are being developed

15. GOES-R Ground System Support
Defining instrument calibration data sets
Calibration data files proposed
Once every two hours; one for each instrument
Example items:
Instrument temperatures
Calibration event data (e.g., internal target and space view counts)
Calibration data statistics (e.g., instrument noise)
Level 1b landmark data
Calibration data will go into GAS (GOES-R Access Subsystem, 7day storage), and CLASS (for long-term)
Collaborating with NSOF calibration specialists to ensure operational monitoring of:
Calibration-related instrument engineering and science data
L0-to-L1b data processing parameters
Work in process, not all instruments have passed CDR

16. Global Space-based Inter-Calibration System
What is GSICS?
Global Space-based Inter-Calibration System
Initiative of CGMS and WMO
An effort to produce consistent, well-calibrated data from the international constellation of operational meteorological satellites
What are the basic strategies of GSICS?
Best practices/requirements for prelaunch characterisation (with CEOS WGCV)
Improve on-orbit calibration by developing an integrated inter-calibration system
Initially by LEO-GEO Inter-satellite/ inter-sensor calibration
This will allow us to:
Improve consistency between instruments
Produce less bias in Level 1 and 2 products
Retrospectively re-calibrate archive data
Better specify future instruments
Well, what is GSICS?
The Global Space-based Inter-Calibration System (GSICS) is an initiative of CGMS and WMO, which aims to ensure consistent calibration and inter-calibration of operational meteorological satellite instruments.
One of the basic strategies of GSICS is to develop an integrated on-orbit cal/val system - initially by LEO-GEO Inter-satellite/inter-sensor calibration.
This will then allow us to provide corrections to improve the consistency between instruments, produce less biased level 1, and therefore, level 2 data, and ultimately, retrospectively re-calibrate archive data, which is of great interest in the climate monitoring community

17. Regional Processing Research Centers at Operational Space
GSICS organization
Organizations contributing to GSICS:
CMA, CNES, EUMETSAT, ISRO, JAXA, JMA, KMA, NASA, NIST, NOAA, WMO
Overseen by GSICS Executive Panel
Assisted by Research Working Group
and Data management Working Group
GSICS activities rely on:
GSICS Coordination Centre (GCC)
operated by NOAA/NESDIS
Processing & Research Centres (GPRC)
operated by each satellite operator
Calibration Support Segments (CSS)
including field sites and laboratories
GSICS as an element of the space-based component of the Global Observing System
GSICS activities rely on a GSICS Coordination Centre (GCC) operated by NOAA/NESDIS, several GSICS Processing and Research Centres (GPRC) operated by each satellite operator, and will benefit of Calibration Support Segments including field sites and laboratories.
Activities are overseen by a GSICS Executive Panel assisted by a Research Working Group and a Data management Working Group.
Coordination Center
Calibration Support Segments (reference sites, benchmark measurements, aircraft, model simulations)
Regional Processing Research Centers at Operational Space
Agencies

18. ECMWF Meeting, Reading UK
June 22, 2001
Applications of GSICS
Quantify the differences – magnitude and uncertainty
Remove the differences – empirical or physical
Understand the differences – root cause analysis and correction/prevention
N:\Briefings\International\ECMWF June \ECMWF Jun_22_2001.ppt

19. GOES Imager 13.3 μm Channel SRF
GOES-13 PLT found Imager Band 6 cold bias of -2.4 K
Original proposal of a -4.7 cm-1 shift of SRF
Instrument vendor revised SRF, effectively shifted -1 cm-1
NOAA implemented additional -2.1 cm-1 shift, eliminated bias and its dependence on scene temperature (not shown)
This is an activity we work with Dr. Simon Kaplan of NIST on SRF of current GOES. I will say in a minute why the current GOES. The story started when large bias was found for a new channel during GOES-13 PLT. Schmit and Gunshor suggested an SRF shift of 4.7 cm-1. ITT found some errors that effectively shifted ~-1 cm-1, and estimated uncertainty of 1.7 – 3.0 cm-1. We eventually shifted additional -2.1 cm-1, which eliminated bias. So all’s well and end well – end of story?
GOES-13 Imager Band 6 spectral response functions, with (green) and without (blue) a -4.7 cm-1 shift, superimposed on spectral radiance for the U. S. Standard Atmosphere (red).
GOES-13 Imager Band 6 spectral response functions, original (blue) and revised (red), superimposed on AIRS spectral radiance for the U. S. Standard Atmosphere (black).
GOES-13 Imager Band 6 radiance difference (in terms of brightness temperature) from AIRS (blue) and IASI (red), two well calibrated hyperspectral instrument used as reference for GSICS.

20. GSICS Monitoring and Correction

21. Impact of GSICS Correction on GOES-12 Imager radiance
Compared to CRTM, GOES-12 Imager Channel 6 bias was reduced from -2.55K before GSICS correction to -0.11K after
T. Zhu, F. Weng

22. Impact of GSICS Correction for GOES-12 Imager radiance on GFS forecast
GOES-12 imager with and without GSICS bias correction
Anomaly Correlation for 500 mb height over tropics (left) and NH (right)
T. Zhu, F. Weng

23. Impact of GSICS Correction for SEVIRI radiance on GFS forecast
MSG SEVIRI CSR with and without GSICS bias correction
Anomaly Correlation for 500 mb height over tropics (left) and NH (right)
T. Zhu, F. Weng

24. Double Difference Technique: A Robust Way for Estimating Sensor to Sensor biases
It reduces the impact related to temporal difference when two instruments have distinct orbits
It reduces the errors related to forward models and from forecast models
It works in the region where the forward model has the same error characteristics
Assumptions:
The same temporal difference from observations and simulations
Negligible forward model biases for two instruments

25. SSMIS TDR Anomalies
( Observation – Simulation )
54.4 GHz V
55.5 GHz V

26. Double Difference Technique (DDT)

27. Summary
PCW calibration can be leveraged from NOAA GOES-R calibration components
GSICS baseline algorithms can be refined for PCW applications