NPP VIIRS Pre-Launch Performance and SDR Validation Frank De Luccia, The Aerospace Corporation, El Segundo, CA Bruce Guenther, NOAA - Joint Polar Satellite System, Goddard Space Flight Center, Greenbelt, MD Chris Moeller, University of Wisconsin, Madison, WI, Xiaoxiong Xiong and Robert Wolfe , NASA’s Goddard Space Flight Center, Greenbelt, MD 2011 IEEE International Geoscience and Remote Sensing Symposium (IGARSS) 24-29 July, Vancouver, Canada
32
Embed
NPP VIIRS Pre-Launch Performance and SDR Validation
NPP VIIRS Pre-Launch Performance and SDR Validation. Frank De Luccia , The Aerospace Corporation, El Segundo, CA Bruce Guenther , NOAA - Joint Polar Satellite System, Goddard Space Flight Center, Greenbelt, MD Chris Moeller , University of Wisconsin, Madison, WI, - PowerPoint PPT Presentation
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
NPP VIIRS Pre-Launch Performance and SDR Validation
Frank De Luccia, The Aerospace Corporation, El Segundo, CABruce Guenther, NOAA - Joint Polar Satellite System, Goddard Space Flight
Center, Greenbelt, MDChris Moeller, University of Wisconsin, Madison, WI,
Xiaoxiong Xiong and Robert Wolfe , NASA’s Goddard Space Flight Center, Greenbelt, MD
2011 IEEE International Geoscience and Remote Sensing Symposium (IGARSS)
– Comparisons to MODIS Aqua as reference• Spectral characteristics• Spatial characteristics • Radiometric sensitivity - SNR and NEdT• Polarization sensitivity
– Performance summary and issues • SDR Validation
– Calibration and Validation (Cal/Val) team– Cal/Val plans and task structure– Principal activities per Cal/Val phase
• Summary
Instrument Background
4
Instrument Background
• NPP VIIRS manufactured by Raytheon under subcontract to Northrop Grumman for NPOESS– NPP instruments now under
3000 km across track by 13 km along track at nadir
2330 km across track by 10 km along track at nadir
Size 1.3 m x 1.4 m x 0.9 m 1.0 m x 1.6 m x 1.0 m
Weight 263 kg 250 kg
Power 154 W 225 W
Data Rate 10.4 Mbps (peak) 11 Mbps (peak)
Quantization 12 bits 12 bits
Design Life 7 years 5 years
5
Instrument Background – cont’d
Flat-panel Cryoradiator
4-Mirror Anastigmat(FMA) All Reflective
Aft Optics Imager
3-Mirror Anastigmat(TMA) All reflectiveRotating telescope
MODISBlackbody
MODISSolar Diffuser
Half-angle Mirror
Separately Mounted Electronics Module
Cold FPADewar Assembly
MODIS derivedSolar DiffuserStability Monitor(SDSM)
6
Environmental Data Products (EDRs) Derived from VIIRS Sensor Data Records (SDRs)
Product Group EDRs/Other ProductsImagery Imagery*
Surface Temperatures
Sea Surface Temperature Land Surface TemperatureIce Surface Temperature
Clouds Cloud Base Height Cloud Top HeightCloud Cover/Layers Cloud Top PressureCloud Particle Size Cloud Top TemperatureCloud Optical Thickness Cloud Mask**
VIIRS Polarization Sensitivity• VIIRS polarization performance is generally
better than that of MODIS. • Unlike MODIS, NPP VIIRS polarization
sensitivity varies strongly with field angle resulting in detector dependence.
• VIIRS pre-launch characterization provides high-quality, per-pixel characterization of polarization sensitivity and phase for use in data product processing.
Performance Summary and Issues• VIIRS performance is comparable or superior to that of MODIS Aqua in
corresponding bands in all key performance areas except crosstalk and out-of-band spectral response. – NPP VIIRS has optical crosstalk in the VisNIR (0.8% average) due to high angle
scattering in the spectral filters• May impact Ocean Color/Chlorophyll and Aerosol data products.
– NPP VIIRS out-of-band (OOB) spectral response somewhat higher than MODIS Aqua due to same scattering mechanism in filters
– Second and subsequent VIIRS flight units will have reduced optical crosstalk and OOB response due to improved spectral filters.
• VIIRS polarization sensitivity is lower than that of MODIS Aqua but is detector dependent– Requires per-pixel correction in Ocean Color processing– Banding effects in SDRs displayed as images
• In other key performance areas not addressed here, such as band-to-band registration, near-field response and stray light response, VIIRS performance compares favorably with that of MODIS Aqua.
SDR Validation
VIIRS SDR Cal/Val Team
14
Organization Key Personnel
NOAA/NESDIS Center for Satellite Applications and Research (STAR)
Changyong Cao - VIIRS SDR Cal/Val Management LeadFuzhong Weng – JPSS SDR Cal/Val ChairMark Liu, Tim Chang
The Aerospace Corporation Frank De Luccia - VIIRS SDR Cal/Val Technical LeadDavid Moyer, Scott Houchin, Kameron Rausch, Christopher Florio, Jason Cardema, Evan Haas, Patrick Yuen, Allen Raines, Jeff Lipeles, Aaron Myrick, Zaven Petrosyan
NASA GSFC• NPP Instrument Characterization Support Team (NICST)• NPP Instrument Calibration and Support Element (NICSE)
Jack Xiong and Kurt Thome - Instrument ScientistsHassan Oudrari, Robert Wolfe, Robert Barnes, Gene Eplee, Fred PattNICST: Jeff McIntire (Lead), Ning Lei, Thomas Schwarting, Junqiang Sun, Alin Tolea, Shihyan Lee, Aisheng WuNICSE: Vincent Chiang (Lead), Mash Nishihama, Gary Lin
University of Wisconsin Chris Moeller
MIT Lincoln Laboratory Juliette Costa, Ed Bicknell
Northrop Grumman Airborne Systems
Lushalan Liao
15
Evolution of VIIRS Calibration and Validation Plans
• On-orbit cal/val tasks were defined in an intensive government-contractor team collaboration– Cal/val strategies draw heavily on MODIS experience– Inputs on specific activities distilled into 54 tasks
• VIIRS SDR Calibration Plan produced and peer reviewed in 2009– Comprehensive description of VIIRS calibration program– Describes team, team interactions, tasks, tools and ground truth resources– Maps cal/val activities into cal/val phases– Provides metrics for evaluating SDR product maturity
• VIIRS SDR Calibration/Validation Operations Concept (OPSCON) Document developed in 2011 – Infrastructure support definition– Data flow and process definition to support cal/val rehearsals
• Managerial leadership has transitioned to Changyong Cao of NOAA STAR– Roles and responsibilities have evolved to reflect increased participation of NOAA
STAR
16
Six Broad Categories of On-Orbit Cal/Val Tasks
• Functional Performance and Format Evaluation (FPF 1-7) – FPF tasks involve evaluating instrument functions and verifying the correctness of data formats.
Performed early in the mission, and will not be repeated unless the instrument suffers a catastrophic event.
• Calibration System Evaluation (CSE 1-6)– CSE tasks evaluate the performance of the onboard calibration system and update the calibration
– IMG tasks evaluate the quantitative and qualitative spatial performance characteristics of the instrument.
• Radiometric Evaluation (RAD 1-25)– RAD tasks evaluate the radiometric performance of the data product algorithm. Radiometric
evaluation will include evaluation of spectral characteristics since changes in these characteristics relative to the pre-launch baseline will mainly manifest themselves as in-band radiometric errors.
• Geolocation Evaluation (GEO 1-7)– GEO tasks evaluate the geolocation accuracy of the data product.
• Performance and Telemetry Trending (PTT 1-5)– PTT tasks evaluate long-term changes in the performance of both the instrument and the data
product.
17
Pre-Launch Activities• Continued analysis and refinement of performance baseline
based on test program• Verification of at-launch SDR algorithm look-up tables (LUTs)
– Improvements where warranted• Operational code review and error checking• Cal/val tool development
– RDR and SDR readers, LUT readers/writers– Custom tools for cal/val analysis tasks
• Practice and training in operation of VIIRS SDR operational code– Algorithm Development Library (ADL) version of code allows cal/val team
to modify and test LUT updates and potential algorithm improvements• Task rehearsals to demonstrate readiness for on-orbit cal/val
18
Early Orbit Checkout (EOC)• Verify instrument operability and functionality
– Signal – Noise– Scan rate
• Compare signal and noise characteristics to pre-launch baseline
• Verify RDR, SDR and intermediate product formats and validity of content
• Early use of Solar Diffuser Stability Monitor– Critical for beginning time series to trend change in Solar Diffuser
• Geolocation match-ups– Ground Control Points (GCPs) from Landsat
• Feedback on SDR quality from EDR validation efforts• Maneuvers• Exploitation of lunar data• SDR algorithm tuning and LUT updates• Continued performance and telemetry trending
Objective is achievement of stable, “validated/calibrated” SDRs by end of ICV.
20
Long-Term Monitoring (LTM)• Routine performance of reflective band off-line calibration • Periodic measurement and trending of key instrument
characteristics– Operability– Noise/SNR– Gains– Critical temperatures, voltages, currents in telemetry
• Periodic repetition of ICV tasks to maintain calibration and SDR quality– Radiometry– Geolocation
21
VIIRS Cal/Val Activities by Phase
L + 50 days
Early Orbit Checkout (EOC) Phase
Intensive Calibration & Validation (ICV) Phase
Pre-Launch Phase
Laun
ch
Long Term Monitoring(LTM) Phase
L + 180 days
SensorCharacterization
Performance & Telemetry Trending
Baseline
SDR Cal/ValPlan Development
SDR AlgorithmInitialization &
Update Capability
Cal/Val ToolDevelopment
FunctionalCheckout
DataInventory
RDR/SDRVerification
RadianceMatch-Ups
Geolocation
Performance &TelemetryTrending
SDR AlgorithmTuning
SDR Parameter
& LUT Updates
RadianceMatch-Ups
Geolocation
Performance &TelemetryTrending
SDR Parameter
& LUT Updates
22
SDR Product Maturity Levels • Beta
– Early release product, initial calibration applied, minimally validated and may still contain significant errors
– Available to allow users to gain familiarity with data formats and parameters – Product is not appropriate as the basis for quantitative scientific publications studies and
applications• Provisional
– Product quality may not be optimal – Incremental product improvements are still occurring as calibration parameters are
adjusted with sensor on-orbit characterization– General research community is encouraged to participate in the QA and validation of the
product, but need to be aware that product validation and QA are ongoing – Users are urged to contact NPP Cal/Val Team representatives prior to use of the data in
publications • Validated/Calibrated
– On-orbit sensor performance characterized and calibration parameters adjusted accordingly
– Ready for use by the Centrals, and in scientific publications– There may be later improved versions
Inter-Satellite Comparisons• Analysis of Simultaneous Nadir
Overpass (SNO) data from VIIRS and other satellites will reveal relative biases
• Off-nadir inter-satellite comparisons will be exploited also, particularly to evaluate Response vs Scan Angle effects
• Leverages validation performed for other satellite systems
• VIIRS/MODIS comparisons expected to be particularly useful– MODIS instruments well validated– Many similar bands with similar
radiometric performance
23
MODIS Terra/AVHRR 11 m Band Comparison(Xiong et al., CEOS-IVOS 2004)
24
CrIS-VIIRS Cal/Val (heritage AIRS-MODIS)
Abundant matchups on every Aqua orbit.
14 orbits per day(>10E6 matchups/day)
AIRS footprints overlain on MODIS image. Filter the sample to retain spatially uniform scenes.
Radiometric performance as function of scene temperature
Radiometric performance as function of scan mirror angle
25
Use of Maneuvers for VIIRS SDR Validation (1)
• S/C Maneuvers for VIIRS Calibration – Scientific benefits and implementation strategies are based on lessons and
experience from heritage missions and sensors, such as MODIS and SeaWiFS– All 3 types of VIIRS maneuvers have been approved for the NPP mission
• Roll Maneuvers– Near monthly event with lunar phase angles at 55 degree and roll angles less
than -14 degrees – Provide an accurate and long-term monitoring of VIIRS RSB calibration
stability and independent monitoring of SD degradation
• Yaw Maneuvers– Once during initial S/C checkout; could repeat every 3 years depending on
the SD degradation rate – Validate SD solar attenuation screen (SAS) and SDSM sun view screen
transmission as a function of solar illumination angles and assure VIIRS SDR quality for the RSB
26
Use of Maneuvers for VIIRS SDR Validation (2)
• Pitch Maneuvers– Once during initial S/C checkout; could repeat depending on scan-angle
dependent changes in TEB responses– Validate sensor response versus scan angle (RVS) and assure VIIRS SDR
quality for the TEB
• Operation and Data Analysis Support– Maneuver implementation working group established to coordinate
among different groups (and instruments) – VIIRS maneuver data analysis tools developed primarily from MODIS
experience
27
Use of Lunar Data for VIIRS SDR Validation (1)
• Track Changes in Sensor Responses for VIIRS Reflective Solar Bands– Both MODIS and SeaWiFS have used lunar time series to track changes in
sensor responses; lunar viewing geometry corrections are made using ROLO lunar model
• Provide Independent Monitoring of VIIRS Solar Diffuser Degradation– The angle of incidence (AOI) of VIIRS space view, through which the lunar
observations are made, is identical to the AOI of SD observations
• Enable Calibration Inter-comparison with Other Sensors (e.g. MODIS)– This is similar to the effort made to inter-compare Terra and Aqua MODIS,
MODIS and SeaWiFS
28
Use of Lunar Data for VIIRS SDR Validation (2)
SeaWiFS Normalized Lunar Radiance Terra and Aqua MODIS B1 Lunar Irradiance
29
VIIRS Geolocation Matchups• Example of first 90 days of control point
matchups from MODIS/Terra• Good (> 60% normalized cross correlation)
control point matchups per day: 260• Used to perform initial refinement of
instrument to spacecraft alignment and to refine rotating telescope and half angle mirror geometric parameters
Aircraft Campaigns • Aircraft underflights can provide high quality radiometric validation
across the VIIRS spectrum– Direct observations of the integrated upwelling earth scene radiance in nearly
same time, space, and geometry as the on-orbit sensor– NIST traceable uncertainties for some airborne instruments
• Approach based upon heritage validation of AIRS, MODIS, IASI.• Preliminary plans for aircraft campaigns have been developed but are
currently “on hold” due to funding constraints • Platforms: ER-2 and/or WB-57• Instruments desired for VIIRS SDR validation
– Enhanced MODIS Airborne Simulator (EMAS)• 50 channel Vis/IR spectrometer, 50 m resolution, 36 km swath • Expected to include reflective solar band (RSB) Hyperspectral Imager (HSI)
– Scanning High-resolution Interferometer Sounder (SHIS)• Scanning M/LWIR 0.5 cm-1 interferometer, 2 km resolution, 32 km swath• NIST traceable calibration
– Cloud Physics Lidar (CPL) • Micropulse dual polarization lidar, 15 m resolution, nadir only
30
31
Approach based upon heritage efforts for AIRS and MODIS
SHIS, etc.on ER-2
q 20 km
705 km
MODIS on Terra/Aqua
11.01 um
Fly instrumented ER-2 along satellite track
Matching geometry of earth scene observations
Histogram of radiometric matchups
32
Summary• VIIRS calibration and validation plans draw heavily on MODIS
strategies and experience– Similar data products– Similar on-board calibrators– Similar radiometric and geolocation retrieval approaches
• VIIRS pre-launch performance baseline very well established– Extensive instrument characterization provided in test program– Independent data analysis by multiple contractor and government
teams has provided highly reliable parameter values for SDR algorithm LUTs
• Experienced, multi-organization calibration/validation team is well prepared to execute VIIRS on-orbit validation