3 Blackwell_IGARSS11_2860_MO3.T04.3.pptx


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  • I will begin with an overview of the ATMS sensor and move onto to validation plans once the NPP satellite launches. The talk concludes with a discussion of applications of the ATMS data.
  • Shown is a picture of the NPP satellite with the five sensors installed.
  • An overview of the ATMS sensor.
  • History of the ATMS development.
  • The principal challenge of the ATMS development was the consolidation of three sensors (AMSU-A, AMSU-B, and MHS) into a single sensor with a longer lifetime requirement.
  • The frequency dependence of atmospheric absorption allows different altitudes to be sensed by spacing channels along absorption lines
  • An overview of the principal differences between ATMS and AMSU.
  • Spatial attributes of ATMS and AMSU.
  • These data products will be derived from ATMS observations.
  • I will begin with an overview of the ATMS sensor and move onto to validation plans once the NPP satellite launches. The talk concludes with a discussion of applications of the ATMS data.
  • The ATMS PFM has completed its characterization and satellite-level testing is mainly to confirm performance after five years. The pre-launch characterization included antenna pattern characterization using a Compact Antenna Test Range (CATR), susceptibility to radio frequency interference, and calibration accuracy and RMS analysis in a thermal vacuum chamber using precision external calibration targets. Listed in the second bullet were some results of the characterization. The sensor had larger than expected non-linearity and required a waiver, but it generally exceeds AMSU. A temperature-dependent NL correction factor was derived from Thermal-Vacuum data. The EDR performance is still being evaluated, but we’re hopeful they can be met with some on-orbit calibration that I’ll discuss more later in the presentation.
  • I will begin with an overview of the ATMS sensor and move onto to validation plans once the NPP satellite launches. The talk concludes with a discussion of applications of the ATMS data.
  • Post-launch cal/val has an extensive history and is becoming increasingly sophisticated. The ATMS SDR validation plan includes Simultaneous Nadir Overpass; Double Difference; radiance comparisons using NWP, radiosondes, and CrIS radiances; aircraft campaigns; satellite maneuvers, etc. Another tool will be an end-to-end ATMS/CrIMSS system error model/budget that will model the system from RDRs to EDRs and will use information derived from sensor thermal-vacuum data, radiative transfer, heritage sensors, and eventually ATMS data. The rest of this presentations will discuss the ATMS proxy data that uses AMSU/MHS, aircraft validation, and on-orbit spacecraft maneuvers.
  • At a very abstract level, here are the objectives and primary components of a successful cal/val campaign. I will touch on most of these during the presentation.
  • ATMS observations will be used to improve forecast accuracy. The microwave instruments have the largest positive impact on forecast accuracy.
  • Recent work is shown where ATMS observations are used to estimate the intensity of precipitation.
  • 3 Blackwell_IGARSS11_2860_MO3.T04.3.pptx

    1. 1. NPP ATMS Prelaunch Performance Assessment and Sensor Data Record Validation<br />W. J. Blackwell, L. Chidester (SDL), C. Cull, E. J. Kim (NASA GSFC), R. V. Leslie,<br /> C.-H. Lyu (NASA GSFC), T. Mo (NOAA STAR), and I. Osaretin<br />IGARSS<br />July 25, 2011<br />This work was sponsored by the National Oceanographic and Atmospheric Administration under Air Force Contract FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the United States Government.<br />
    2. 2. Outline<br />ATMS Overview<br />Background and development<br />Performance<br />Prelaunch testing<br />Antenna<br />Radiometric TVAC<br />Post-launch validationof sensor/product performance<br />Planning/schedule/objectives<br />Tasks<br />Summary<br />
    3. 3. NPOESS Preparatory Project<br /><ul><li>Launch site: Vandenberg AFB
    4. 4. Launch vehicle: Boeing Delta II
    5. 5. Spacecraft: Ball Aerospace Commercial Platform 2000
    6. 6. Instruments: VIIRS, CrIS, ATMS, OMPS, & CERES
    7. 7. Orbits: 824 km (NPP); sun-synchronous with a 1:30 p.m. local-time ascending node crossing</li></ul>NPP (NPOESS Preparatory Project)<br />Oct. 25, 2011 Launch<br />National Polar-orbiting Operational Environmental Satellite System -> Joint Polar Satellite System<br />
    8. 8. NPOESS Preparatory ProjectOctober 25, 2011 Launch<br />Photo courtesy of Ball Aerospace, Boulder, CO.<br />
    9. 9. Advanced Technology Microwave Sounder (ATMS)<br />ATMS is a 22 channel MW sounder<br />Frequencies range from 23-183 GHz<br />Total-power, two-point external calibration<br />Continuous cross-track scanning, with torque & momentum compensation<br />Orbits: 833 km (JPSS); 824 km (NPP); sun-synchronous<br />Thermal control by spacecraft cold plate<br />Contractor: Northrop Grumman Electronics Systems (NGES)<br />70 cm<br />
    10. 10. ATMS Development<br />ATMS NPP unit (“F1") developed by NASA/Goddard<br />ATMS NPP unit delivered in 2005<br />ATMS JPSS-1 unit (“F2”) currently in development (antenna and TVACtesting in 2011/12, delivery in 2012)<br />Principal challenges/advantages:<br />Reduced size/power relative to AMSU<br />Scan drive mechanism<br />MMIC technology<br />Improved spatial coverage (no gaps between swaths)<br />Nyquist spatial sampling of temperature bands (improved information content relative to AMSU-A)<br />
    11. 11. ATMS Design Challenge<br />AMSU-A1<br />Reduce the volume by 3x<br /><ul><li>73x30x61 cm
    12. 12. 67 W
    13. 13. 54 kg
    14. 14. 3-yr life</li></ul>AMSU-A2<br /><ul><li>75x70x64 cm
    15. 15. 24 W
    16. 16. 50 kg
    17. 17. 3-yr life</li></ul>MHS<br /><ul><li>75x56x69 cm
    18. 18. 61 W
    19. 19. 50 kg
    20. 20. 4-yr life
    21. 21. 70x40x60 cm
    22. 22. 110 W
    23. 23. 85 kg
    24. 24. 8 year life</li></ul>Figure courtesy NGES, Azusa, CA<br />
    25. 25. Atmospheric Transmission at Microwave Wavelengths<br />ATMS channels<br />The frequency dependence of atmospheric absorption allows different altitudes to be sensed by spacing channels along absorption lines<br />
    26. 26. Spectral Differences: ATMS vs. AMSU/MHS <br />AMSU/MHS<br />ATMS<br /><ul><li>ATMS has 22 channels and AMSU/MHS have 20, with polarization differences between some channels</li></ul>− QV = Quasi-vertical; polarization vector is parallel to the scan plane at nadir<br /> − QH = Quasi-horizontal; polarization vector is perpendicular to the scan plane at nadir<br />AMSU-A<br />Exact match to AMSU/MHS<br />Only Polarization different<br />Unique Passband<br />MHS<br />Unique Passband, and Pol. different <br />from closest AMSU/MHS channels<br />
    27. 27. Spatial Differences: ATMS vs. AMSU/MHS<br />Beamwidth (degrees)<br />Spatial sampling<br />ATMS scan period: 8/3 sec; AMSU-A scan period: 8 sec<br />ATMS measures 96 footprints per scan (30/90 for AMSU-A/B)<br />
    28. 28. Summary of Key Sensor Parameters<br />
    29. 29. ATMS Data Products<br />1FOV = ATMS “Field of View”; FOR = CrIMSS “Field of Regard”<br />RDR, TDR, SDR, and EDR products will be available via CLASS<br />
    30. 30. Outline<br />ATMS Overview<br />Background and development<br />Performance<br />Prelaunch testing<br />Antenna<br />Radiometric TVAC<br />Post-launch validationof sensor/product performance<br />Planning/schedule/objectives<br />Tasks<br />Summary<br />
    31. 31. ATMS Pre-Launch Testing<br />Essential for two objectives:<br />Ensure sensor meets performance specifications<br />Ensure calibration parameters that are needed for SDR processing are adequately and accurately defined<br />PFM testing revealed several issues that will require calibration corrections in the SDR:<br />Non-linearity (temperature-dependent for 31.4-GHz channel)<br />Cross-polarization (sometimes 10X higher than AMSU)<br />Antenna beam spillover from secondary parabolic reflector approaching 2% for some channels<br />A variety of prelaunch testing is performed to assess performance and reliability<br />EMI/EMC - anechoic chamber for both emitted and susceptible measurements <br />Mechanical – mass, CG, vibration, & torque on various fixtures<br />Radiometric – thermal vacuum (TVac) testing<br />Antenna – Compact Antenna Test Range (CATR)<br />
    32. 32. Compact Antenna Range Testing<br />Compact Antenna Test Range<br />RF source illuminates the Antenna Under Test (AUT), i.e., ATMS antenna subsystem<br />Uses a parabolic reflector to collimate the electromagnetic radiation to illuminate the AUT in the far-field region <br />AUT is attached to a positioner to rotate the AUT into the proper orientation<br />Test measures the power received by the AUT compared to a standard antenna with a known antenna gain pattern<br />Specifications verified: <br />Beam pointing accuracy<br />Beamwidth<br />Beam efficiency<br />Earth intercept<br />
    33. 33. Thermal Vacuum Parameters<br />Dynamic range (brightness temperature range of 93-320 K)<br />NEΔT (sensitivity)<br />Calibration accuracy (bias)<br />Linearity (deviation from linear regression)<br />Short term gain fluctuation (ΔG/G) (gain stability or 1/f noise)<br />Hysteresis (repeatability)<br />NASA/LARC<br /><ul><li>Measure the calibration parameters that are needed by the SDR algorithm (e.g., non-linearity correction factor)
    34. 34. Validate that the sensor meets performance requirements
    35. 35. Provide pre-launch performance validation in a flight-like environment</li></li></ul><li>Outline<br />ATMS Overview<br />Background and development<br />Performance<br />Prelaunch testing<br />Antenna<br />Radiometric TVAC<br />Post-launch validationof sensor/product performance<br />Planning/schedule/objectives<br />Tasks<br />Summary<br />
    36. 36. Post-Launch Cal/Val Timeline<br />L+90<br />L+12<br />L+13<br />L+ 40<br />IPO/NGAS ATMS<br />NASA/NGES<br />NGES/NASA<br />
    37. 37. ATMS Post-Launch Calibration/Validation in a Nutshell<br />Post-launch is Cal/Val has four phases: Activation, Checkout, Intensive Cal/Val, and Long-term Trending<br />Tasks within the phases can be categorized:<br />Sensor Evaluation: interference, performance evaluation, etc.<br />TDR/SDR Verification: geolocation, accuracy, etc.<br />SDR Algorithm Tunable Parameters: bias correction, space view sector, etc.<br />Activation Phase: Sensor is turned on and a sensor functional evaluation is performed; ATMS is collecting science data<br />Checkout Phase: Performance evaluation and RFI evaluations<br />Intensive Cal/Val: Verification of SDR attributes such as geolocation, resampling, brightness temperature accuracy (Simultaneous Nadir Overpass, Double Difference, radiosondes/NWP simulations, aircraft verification campaigns), and satellite maneuvers<br />
    38. 38. ATMS On-Orbit FOV Characterization<br />Spacecraft maneuvers (constant pitch up or roll, for example) could be used to sweep antenna beam across vicarious calibration sources<br />Moon (probably too weak/broad for pattern assessment)<br />Earth’s limb (requires atmospheric characterization)<br />Focus of today’s presentation<br />Land/sea boundary (good for verification of geolocation)<br />With knowledge of the atmospheric state, the antenna pattern can be recovered with deconvolution techniques<br />Objectives of this study - quantitatively assess:<br />The benefits of various maneuvers <br />How accurately can the pattern be recovered?<br />The limitations of this approach<br />How much roll/pitch is needed for an adequate measurement?<br />The error sources and their impact<br />
    39. 39. TB’s Across Earth/Space Transition<br />LIMB<br />(STANDARD<br />ATMOSPHERE)<br />SURFACE<br />BEYOND STANDARD ATMOSPHERE<br />62.17°<br />
    40. 40. 54<br />183<br />425<br />118<br />NPOESS Airborne Sounder Testbed<br />NAST<br />OBJECTIVES<br /><ul><li>Satellite calibration/validation
    41. 41. Simulate spaceborne instruments </li></ul> (i.e. CrIS, ATMS, IASI)<br /><ul><li>Preview high resolution products
    42. 42. Evaluate key EDR algorithms</li></ul>INSTRUMENTS: NAST-I & NAST-M<br />NAST- I: IR Interferometer Sounder<br />NAST- M: Microwave Sounder<br />5 Bands: 23/31 (to be added), 54, 118, 183, 425 GHz<br />~100km<br />NAST- M<br />Cruising altitude: ~17-20 km<br />Cross-track scanning: - 65º to 65º<br />
    43. 43. MetOp Satellite Validation <br />JAIVEx<br />Tb Comparison AMSU-A<br />April 20th, 2007 collection<br />GHz Bias<br />50.3<br />-0.25K<br />52.8<br />1.4K<br />53.75<br />-0.2K<br />Gulf of Mexico<br />-0.2K<br />54.4<br />AMSU-A (MetOp) [Kelvin]<br />54.94<br />-0.9K<br /><20min<br />MetOp<br /> path<br />NAST-M [Kelvin]<br />
    44. 44. Summary<br />All key radiometric requirements were satisfied<br />Radiometric accuracy exceeds 1K<br />Radiometric sensitivity exceeds requirements<br />Similar to AMSU for similar effective footprint sizes<br />Linearity performance generally exceeds AMSU<br />Antenna pattern testing indicates good performance<br />Opportunity for spacecraft maneuvers allows improved characterization of ATMS spatial response function<br />Post-launch cal/val plans are well defined<br />Readiness exercises ongoing<br />Areas to watch have been illuminated during prelaunch testing<br />
    45. 45. Backup Slides<br />
    46. 46. Utility of Aircraft Underflights<br />What do aircraft measurements provide that we cannot get anywhere else?<br />Why not just compare to radiosondes or NWP?<br />Direct radiance comparisons<br />Removes modeling errors<br />Mobile platform<br />High spatial & temporal coincidence achievable<br />Spectral response matched to satellite<br />With additional radiometers for calibration<br />Higher spatial resolution than satellite<br />Additional instrumentation deployed<br />Coincident video data<br />Dropsondes<br />Example video image<br />Solar <br />glint<br />Ocean<br />Clouds<br />
    47. 47. Synergistic Use of MW+IR:Infrared Provides High Spatial Resolution<br />For example, CrIS provides 15km horizontal and 1km vertical resolution<br />
    48. 48. Passive Microwave Measurements Provide Low Spatial Resolution, but Penetrate Clouds<br />For example, ATMS provides 33km horizontal and 3km vertical resolution<br />
    49. 49. AMSU-A: Large, Positive Forecast Impact<br />Source: Gelaro, Rienecker et al., 2008, NASA GMAO<br />
    50. 50. ATMS Storm Mapping:Improvements Relative to AMSU<br />Source: Surussavadee and Staelin, NASA PMM Presentation, 7/08<br />