Status of Cross-Track Infrared Sounder (CrIS) Pre–launch Calibration: Update Denise Hagan, Chunming Wang, Giovanni De Amici, Degui Gu (Northrop Grumman Space Technology) Denis Tremblay (Science Data Processing Inc.) Gene Kratz (Raytheon Information Systems) AIRS and NPP Sounding Team Meeting Pasadena, California May 4, 2009 5/04/09 1
Objectives • Provide update on status of calibration activities, since last AIRS/NPP meeting in October – TVAC test status – Current FM1 Internal Calibration Target (ICT) emissivity – External Calibration Target (ECT) NIST transfer – Non-linearity correction – Key CalVal milestones • Poster in lobby area describes over-all calibration and key performance parameters • Revercomb et al presentation (this session) provides overview of instrument absolute radiometry including correction methodology for non-linearity effects 5/04/09 2
TVAC Test Status (1/2) • CrIS system level testing performed during TVAC1 and TVAC2 in spring and summer (‘09) including – Cooler, cold start, survival heaters – EMI – Vibration – Dynamic interaction – Thermal cycling and balance – FOV Slit and Spot Scan – Radiometric calibration at 3 different instrument temperature regimes, including NEdN, long and short-term repeatability, non-linearity – Spectral ILS and accuracy measurements (Gas Cell) at 3 different instrument temperature regimes (e.g. Mission Nominal, Protoqual Low and Protoqual High) – Scan scenario (multiple orbits) • TVAC3 radiometric regression testing using replacement ICT (from EDU3) completed late ‘09 – Includes repeat of non-linearity testing – Includes test to determine ICT cavity emissivity 5/04/09 3
TVAC Test Status (1/2) • CrIS system level testing performed during TVAC1 and TVAC2 performed during spring and summer (‘09) including – Cooler, cold start, survival heaters – EMI – Vibration – Dynamic interaction – Thermal cycling and balance – FOV Slit and Spot Scan – Radiometric calibration at 3 different instrument temperature regimes, including NEdN, long and short-term repeatability, non-linearity – Spectral ILS and accuracy measurements (Gas Cell) at 3 different instrument temperature regimes (e.g. Mission Nominal, Protoqual Low and Protoqual High) – Scan scenario (multiple orbits) • TVAC3 radiometric regression testing using replacement ICT (from EDU3) completed late ‘09 – Includes repeat of non-linearity testing – Included test to determine ICT cavity emissivity 5/04/09 4
TVAC Test Status (2/2) Summary of Key Performance Analyses • NEdN Trending • Spectral overlay and comparisons with line-by-line models • Non-linearity • Short and long term repeatability • Target effective emissivity retrievals • Spatial registration/spot size and center positions • Scan scenario • Dynamic Interaction effects All analyses are completed 5/04/09 5
Current FM1 ICT Emissivity • Curve shows emissivity values currently used in SDR algorithm for radiometric cal • ITT Derived ICT cavity effective emissivity almost exactly matches NIST measurements of coating coupon B ‘dull’ Enhanced Martin Black ICT Retrieved Effective and Surface Emissivities using TSSR Constraint in SWIR (FM1-3 IR15565 Step 112, PQH Side1, Target =-180C, ECT=315.12, ICT=315.06, 10/19/08 20:13:36-22:22:30) ITT cavity 1.00 emissivity retrieved TSSR Measurement 0.99 0.976 0.006 Emissivity 0.98 0.97 0.96 0.95 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 5/04/09 6 Wavenumber (cm -1 )
ECT NIST Transfer • ICT/ECT PRTs NIST traceable • ECT NIST radiance transfer activities are funded – Measure spatial variation of outgoing radiance of ECT using NIST TXR – ECT reflectance measurements (under review as new scope) • TRR held March ’09 • Test on hold pending purchase of NIST translation stage • Measurements should provide additional margin for assessing instrument absolute radiometric uncertainty 5/04/09 7
Non-linearity • Non-linearity corrections incorporated into latest version of SDR algorithm (V2.18) • Corrections work well, reducing non-linearity to about 0.1% or better for most scene temperatures (See Revercomb et al this session) • Efforts moving toward addressing on-orbit method for non-linearity assessment 5/04/09 8
Key CV Milestones • CrIS PSR scheduled July 15 ’09 • NIST ECT calibration Aug ’09 (tentative) • NPOESS CDR completed (April ’09) – CrIS NPP and NPOESS C1 SDR CalVal plans under CM at NGAS – CrIS EDR CalVal plan in progress for review by external community (Summer ‘09) 5/04/09 9
Back-ups 5/04/09 10
CrIS Noise vs. Heritage Sensors Chart added to address question that arose from M. Chahine at Oct ’09 presentation Courtesy C. Barnet, NOAA 5/04/09 11
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