1. Participating SDR Team Members Cross-track Infrared Sounder
Calibration and Validation Plan of the JPSS Crosstrack Infrared Sounder (CrIS)
Deron Scott1, Gail Bingham1, Chad Fish1, Harri Latvakowski1 , Mark Greenman1, Mark Esplin1, Vladimir Zavyalov1, Yong Han2
1Space Dynamics Laboratory, Utah State University 2National Oceanic and Atmospheric Administration
Abstract
Calibration and Validation Process
Calibration and validation of sensors is important for understanding how a sensor operates during its mission and shows the level of measurements that can be expected. Calibration is an on-going process throughout the mission but is most critical when the complete system comes together and during its initial stage after reaching orbit. Careful planning is required to accurately and efficiently collect data that characterizes the sensors response, process the data in a timely manner to generate results that are useful to mission science, apply the results for processing algorithms, and have a process for improvement as additional information about the sensor becomes available. This paper describes the calibration and validation plan of early on-orbit operations of the Cross-track Infrared Sounder (CrIS). It focuses on the science data record (SDR) portion of the CrIS mission. The CrIS sensor is currently integrated on the NPP spacecraft that is scheduled to launch in October 2011.
Early Orbit Check-out
Purpose: To allow post-launch Cal/Val activities to begin, the NPP spacecraft must be successfully launched and checked out and sensor activation initiated. Because CrIS has cryogenic temperature components, it will undergo an extensive outgas period before it is for ready for performance assessment. The outgassing period will reduce/avoid the likelihood of cryo-ice or other contaminants to build up on the sensor
Activation activities have the primary objective of safely and effectively getting CrIS into operational conditions, including electrical checkout, out-gassing, cooling the detectors, setting the gains and bit trim masks and other necessary functions to allow data flow to begin.
CrIS sensor will be activated through a stepwise process that moves the instrument from the OFF mode to the DIAGNOSTIC mode. NGST assisted by ITT and working with NASA spacecraft have responsibility to perform the sensor activation. MIT will review and contribute as needed.
Pre-launch Ground Testing Calibration/Validation
Completed
Rehearsal Using Proxy Data Sets
On-going
Launch and Sensor Activation
Early Orbit Check-out
L + 55 days
Intensive Cal/Val
L + 90 days
Long-term Monitoring
L days
NPP Mission Phase
Participating SDR Team Members
NASA,
NOAA-STAR
JPSS Program
ITT
UWisc./SSEC
UMBC
Raytheon
NGAS
USU/SDL
MIT/LL
Aerospace
Cross-track Infrared Sounder
(CrIS)
ITT Corporation
The Cross-track Infrared Sounder (CrIS) is part of the NPP system that will be used to produce accurate temperature, water vapor, and pressure profiles on the Joint Polar Satellite System (JPSS) operational missions.
Aspects of CrIS related to calibration:
CrIS sensor measures top of the atmosphere spectral radiance, which is then further processed to develop the temperature, pressure, and water vapor profiles.
Fields of Regard 3 x 3 grid
14 km nadir FOV spatial resolution
On-board internal calibration target
2200 km swath width
±50° Cross track Scans
RDR = Raw Data Record
SDR = Sensor Data Record
EDR = Environmental Data
Record
CrIS Swath 2200km
RDRs
EDR Algorithms
Decode Spacecraft Data
SDR Algorithms
• CrIS
3x3 Array of CrIS FOVs (Each at
14-km Diameter)
Central or Regional Ground Stations
SDRs
0.1 1 10
100
1000
200
210
220
230
240
250
260
270
280
290
Temperature (K)
Pressure (mb)
EDRs
Co-located ATMS SDRs
CrIS
CrIS Sensor Overview:
Intensive Calibration and Validation
Purpose: To derive calibration parameters and validate operation of the CrIS sensor.
Tasks from early orbit check-out, ICV, and Long-term monitoring flow into each other making dividing lines blurry.
During ICV, any anomalies or inconsistent data sets will be investigated to determine if adjustments in the sensor need to be made.
The following tasks will be completed (Note, tasks are numbered consistent with the calibration plan.) :
Task 1: Interferometer Optimization
Task 2: Set Neon Lamp Calibration
Task 3: IR Channel Programmable Amplifier Gain Check and Adjustment
Task 4: Bit Trim and Impulse Mask Checks
Task 7: Detector Linearity Check and Adjustment
Task 8: Geolocation Calibration
Task 9: ICT External Environmental Radiance Model Assessment and Tuning
Task 10: Verification of Onboard Filtering and Decimation of the Interferogram
Task 12: Spike Analysis
Task14: Correlated/Uncorrelated Noise Characterization
Task 15: Residual Analysis
Task 18: Error Budget Assessment
Task 20: Early Broadband Radiance Comparisons with GOES and other Geos
Pre-launch Ground Testing Calibration/Validation
Purpose: Characterize sensor, determine calibration coefficients and Look up tables (LUTs), verify data processing algorithms
Four TVAC tests performed
Thermal-Vac Testing performed at ITT and Ball Aerospace
Initial system level checkout
Calibration parameter derivation
Final Validation
Spacecraft system level TVAC test
Parameters Derived
Long-Term Monitoring
Purpose: To verify that the sensor continues to operates at well characterized levels and variations are documented and understood.
Cal/Val team provides careful tracking and comparisons with reference systems working closely with EDR and Centrals teams. This phase will include SI traceability establishment via aircraft campaign. Continued evaluation of instrument and SDR code issues and IDPS SDR code fine tuning.
The following tasks were started during ICV and will be completed:
Task 5: Noise Equivalent Radiance Difference (NEdN) Check
Task 6: Spectral Calibration
Task 11: Responsivity and Sensitivity Characterization
Task 13: Ice Contamination Analysis
Task 16: Double-difference Cross Comparison with AIRS and IASI
Task 17: SNO Cross Calibration with AIRS and IASI
Task 19: CrIS RDR and SDR Trending and Monitoring
CrIS follows two great, well calibrated instruments to orbit
SDR Cal/Val has/will utilize similar procedures
Co-existence enables direct comparison, and good comparisons from GSICS
Cal/Val team brings direct AIRS/IASI experience
CrIS
AIRS
IASI
Ground testing results show that CrIS is an outstanding instrument compliant to requirements with few exceptions
Rehearsal Using Proxy Data Sets
Purpose: Verify that software tools can read and process data from sensor.
Validation is based on comparisons of CrIS radiances with other satellite sensors
Data sets available:
P-72: 6 orbits of contiguous data using AIRSS as a baseline
NCT?-V? Continuous data sets from multiple rehearsals multiple versions using thermal-vacuum data as a base line
IASI proxy: Single orbit using IASI as a baseline
Data from TVAC testing
Analysis tools available:
GRAVITE: Software and hardware system to allow easy access and processing of data sets.
TVAC tools: Many of the analysis tools developed during TVAC testing will be used during on-orbit analysis.
GTP: Gravite transfer protocol. Used to retrieve directories and files.
Peate: Product and evaluation test element. Includes both atmospheric and sounding elements
CLASS: Comprehensive Large Array-data Stewardship System. Long-term data repository
Summary:
NPP Mission
CrIS integrated into spacecraft awaiting October launch
Ground testing performed in 4 thermal vacuum tests and spacecraft integrated test.
Rehearsal and proxy data available for software tool testing and model predictions
On-orbit calibration loosely divided into early orbit operations, intensive calibration/validation, and long term monitoring
CrIS/ATMS Cal/Val plans have been carefully coordinated to assure comparable results and timing
In development and testing: Cal/Val tools and procedures
NPP mission major objectives:
To provide continuation of the group of Earth system observations initiated by the Earth Observing System (EOS) Terra, Aqua, and Aura mission
To provide the operational forecasting community with pre operational risk reduction, demonstration, and validation for selected JPSS instruments and ground processing data systems.
Five sensors will be flown on the NPP mission
Visible Infrared Imaging Radiometer Suite (VIIRS)
Cross-track Infrared Sounder (CRIP)
Advanced Technology Microwave Sounder (ATMS)
Ozone Mapping an profiler Suite (OMPS)
Clouds and the Earth’s Radiant Energy System (CERES)
Calibration and Validation demonstrate that the CrIS sensor is ready to perform its mission objectives.