CERES Instrument Overview / Calibration Kory J. Priestley Climate Science Peer Review NASA Langley Research Center June 5th, 2007

NASA Langley Research Center / Science Directorate Role and responsibilities of the CERES Instrument Working Group in the Radiation Sciences Program CERES Instrument Overview Radiometric Calibration Goals and on-orbit performance Instrument Overview / Calibration

NASA Langley Research Center / Science Directorate SNOW-ICE MAPS ATMO STRUCTURE AEROSOLS CERES DATA PROCESSING FLOW CERES CALIBRATION/ LOCATION ERBE INVERSION ERBE AVERAGING ERBE-LIKE PRODUCTS CERES DATA TRMM, Terra, Aqua CLOUD ID; TOA/SURFACE FLUXES ANGULAR DISTRIBUTION MODELS SURFACE AND ATMOSPHERIC FLUXES TIME/SPACE AVERAGING CERES TIME AVERAGE CLOUD/RADIATION TOA, SFC, ATMOS GEOSTATIONARY DATA 3-hourly 1-degree grid High level of data fusion; up to 11 instruments on 7 spacecraft all integrated to obtain climate accuracy in top to bottom fluxes ~ 8-dimensional radiative assimilation CLOUD IMAGER DATA SOLAR ZEN. ALBEDO MODELS CERES TOA & SURFACE PRODUCTS LaRC Fu-Liou RADIATIVE MODEL GEOSTATIONARY DATA monthly 1-degree grid

NASA Langley Research Center / Science Directorate Characterize and calibrate the instrument spectrally, spatially and radiometrically Responsible for ensuring instrument performance is in consonance with all science objectives Continually looking at ways to improve measurement technology to maximize scientific return Long term goal is to minimize the dichotomy between science, engineering, and project management CERES Instrument Working Group

NASA Langley Research Center / Science Directorate Design is based upon the Earth Radiation Budget Experiment (ERBE) philosophy Instrument was designed, manufactured and tested by TRW (Redondo Beach, CA) Contains three sensor assemblies with cassegrain optics and thermistor bolometer detectors Sensors measure thermal radiation in the near-visible through far-infrared spectral region Three sensor channels are coaligned and mounted on a spindle which rotates about the elevation axis Hemispherical sampling obtained with an azimuthal axis drive system Calibration Accuracy Requirements - 0.5% LW, 1.0% SW CERES Instrument

NASA Langley Research Center / Science Directorate Fixed Azimuth Plane Scanning (FAPS, Xtrack) Rotating Azimuth Plane Scanning (RAPS) Primary CERES Operational Modes

NASA Langley Research Center / Science Directorate Proto-Flight Model Sample Note: LW DAY = Total - Shortwave CERES Spectral Response Function

NASA Langley Research Center / Science Directorate Requirements for CERES are more stringent than ERBE’s by a factor of 2 Requirements per Ohring et. al. are more stringent than CERES by a factor of 3-5 Spectral Regions SolarTerrestrial Atmospheric Window Wavelengths  m  m  m Scene levels<100 w/m 2 -sr>100 w/m 2 -sr<100 w/m 2 -sr>100 w/m 2 -srAll Levels Accuracy Requirements 0.8 w/m 2 -sr1.0 %0.8 w/m 2 -sr0.5 %0.3 w/m 2 -sr Stability Requirements < 0.14%/yr< 0.1%/yr Climate Stability Goals < 0.6 w/m 2 /dec < 0.03 %/yr < 0.2 w/m 2 /dec < 0.02%/yr Radiometric Performance Requirements 5-Year CERES Mission Lifetime

NASA Langley Research Center / Science Directorate CERES Terra/Aqua Health & Status With the exception of the SW channel on the CERES/Aqua FM-4 Instrument, the CERES Terra/Aqua instruments are functioning nominally… SpacecraftInstrumentsLaunch Science Initiation Collected Data (Months) TRMMPFM11/971/989 TerraFM1, FM212/993/ AquaFM3, FM45/026/ NPPFM52009? Instrument Years of Data

NASA Langley Research Center / Science Directorate Cal-Val Approach Pre-Launch -Implement a rigorous & thorough ground calibration/characterization program -Cal/Val role must be prominent in original proposal and SOW -System level characterization is typically last test performed prior to delivery of the instrument -Cost and schedule constraints typically drive programs at that point Post-Launch -Implement a protocol of independent studies to characterize on-orbit performance -Studies should cover all spectral, spatial and temporal scales as well as data product levels -Continuous development of new validation studies Data Product Release Strategy -Develop a logical and well understood approach to data release. -Minimize the number of Editions/Versions of Data -Utilize Data Quality Summaries for the community

NASA Langley Research Center / Science Directorate Radiometric Calibration Facility Narrow Field of View Blackbody (NFBB) is primary standard (Emissivity of greater than ) 12.5 cm Wide Field of View Blackbody (WFBB) Cold Space Reference (CSR) blackbodies New SW reference source (SWRS) with minimum LW variations and better spectral characterization 5 cm i.d. integrating sphere with associated optics Cryogenically cooled Transfer Active Cavity Radiometer (TACR) Point Response Function characterization source Constant Radiance Reference to determine scan dependent offsets Earth infrared radiation simulators Liquid nitrogen cooled shroud wall

NASA Langley Research Center / Science Directorate Product Spatial Scale Temporal Scale Metric Spectral Band Internal BB Filtered Radiance N/A Absolute StabilityTOT, WN On-BoardInternal Lamp Filtered Radiance N/A Absolute StabilitySW Solar Filtered Radiance N/A Relative StabilityTOT, SW Theoretical Line-by-Line Filtered Radiance > 20 KmInstantaneous Inter-Channel Theoretical Agreement TOT, WN Unfiltering Algorithm Theoretical Validation N/A TOT, SW, WN Inter-satellite (Direct Comparison) Unfiltered Radiance 1-deg Grid1 per crossing Inter-Instrument Agreement, Stability TOT, SW, WN Vicarious Globally Matched Pixels (Direct Comparison) Unfiltered Radiance Pixel to PixelDaily Inter-Instrument Agreement TOT, SW, WN Tropical Mean (Geographical Average) Unfiltered Radiance 20N – 20SMonthly Inter-Channel Agreement, Stability TOT, WN DCC Albedo Unfiltered Radiance >40 KmMonthly Inter-Instrument agreement, Stability SW DCC 3-channel Unfiltered Radiance >100 KmMonthly Inter-Channel consistency, stability TOT, SW TIme Space AveragingFluxesGlobalMonthly Inter-Instrument Agreement LW, SW Lunar Radiance Measurements Filtered Radiance Sub PixelQuarterly Inter-Instrument Agreement LW, SW, WN CERES Instrument Radiometric Validation Activities

NASA Langley Research Center / Science Directorate BDS and ERBE-Like Data Product Release Strategy Edition1_CV - Static Algorithms and coefficients - baseline product used in cal/val protocol Edition2 - Utilizes temporally varying coefficients to correct for traceable radiometric drift. All spectral changes are broadband and ‘gray’. Edition3 - Release date Fall Will incorporate temporally varying spectral artifacts in the SW measurements. A complete re-analysis of Ground Calibration with additional component characterization measurements. User Applied Revisions - Advance capabilities to the users prior to the release of the next Edition. Edition2 products lag Edition1 by a minimum of 4 months

NASA Langley Research Center / Science Directorate Note: Values apply to all-sky global averages Units are in %/yr Edition1_CVEdition2Edition2_Rev1Edition 3 FM1FM2FM3FM4FM1 FM 2 FM3FM4FM1 FM 2 FM3FM4FM1FM2 FM 3 FM4 LW day <.1 LW night <.1.1 <.1.1 <.1 SW <.1.25 <.1 WN<.1.1 <.1.1 <.1.1 <.1 (Anticipated) Cal/Val Protocol demonstrates radiometric stability of the data products through 12/2006 of…. CERES Unfiltered Radiance Summary

NASA Langley Research Center / Science Directorate Lessons Learned / Future Direction How do we move CERES towards achieving the new climate calibration stability goals? In the future there will only be a single CERES or CERES II instrument per spacecraft, eliminating key Direct Comparison validation capabilities… New Programmatic Paradigms - Maintain positive/open relationship with hardware provider. Avoid ‘Us’ vs. ‘Them’ mentality. Handling Procedures - Keep instruments clean, develop inspection/cleaning procedures. Ground Characterization Procedures - Improve absolute traceability, Collaborate with NIST, other international agencies Operational Mode - Do not point optics in ‘forward’ looking direction Hardware Improvements - Improve post-launch spectral characterization capabilities