Climate Absolute Radiance and Refractivity Observatory (CLARREO) Summary

1. Climate Absolute Radiance and Refractivity Observatory(CLARREO)Summary David Young Project Scientist CLARREO Mission Formulation Team NASA Langley Research Center May 12, 2009

2. What we’ve accomplished • We have reviewed our work so far • We have identified key risks to mission success • We’ve agreed to the high-level requirements for both IR and GPS observations • We’re close to agreement on an approach for the SW observations • We will identify continued studies to resolve outstanding issues. • Resolve polarization question with HQ • Next: We will draft the science objectives Next:

3. Level 1 Requirements and Mission Success Criteria Document • 2SCIENCE DEFINITION 6 • 2.1MISSION SCOPE 6 • 2.2MISSION OBJECTIVE 7 • 2.3SCIENCE OBJECTIVES 7 • 2.4IMPLEMENTATION APPROACH 7 • 3PROGRAMMATIC REQUIREMENTS 15 • 3.1SCIENCE MEASUREMENT REQUIREMENTS 15 • 3.2MISSION AND SPACECRAFT PERFORMANCE 16 • 3.3MISSION CONTINUITY REQUIREMENT 16 • 3.4LAUNCH REQUIREMENTS 17 • 3.5GROUND SYSTEM REQUIREMENTS 17 • 3.6MISSION DATA REQUIREMENTS 17

4. Action • Draft Requirement document sections (June 1) • Dave Y / team • Draft Science Objectives (May 22) • Bruce / Team • Draft Science Measurement Requirements (May 22) • Marty / team • Draft SW Science Measurement Requirements (May 22) • Kurt / team • Draft GPS Science Measurement Requirements (May 22) • Stephen / Tony / team

5. Action • Dual vs. single instrument analysis • Marty / team • Document SW issues with plan / schedule to solve • Kurt • Submit Science Requirement Reports!!!!!!! (May 29) • All • Resolve differences on polarization effects on calibration • Lukashin / Mischenko • Involve NIST • Communicate • Evaluate mission options (Steve S)

6. Outstanding Issues - IR • Two instruments per spacecraft or one? • Cast argument in terms of verification and validation strategy • Clearly defined flow down from science objective to measurement requirements in ”NASA methodology” • Spectrally dependent error specs for input to OSSEs & studies • Specify uncertainty in fingerprints • Statements of science for 3 to 5 year ‘foundation’ mission • e.g., far-IR science; cross-cal science; SI-traceable record; • “Conventional” ground/aircraft based validation • 10 km IFOV needed for validation et al? (K Bowman) • Far-IR validation - • High precision of earthbound sensors vs. CLARREO • Contamination effects on mirror polarization stability (to hold at nadir-only pointing) • Pointing – accuracy and knowledge. • Factor in effect on image motion compensation requirement

7. Outstanding Issues - SW • See other file

8. Outstanding Issues - GPS • Resolve orbit sampling concerns • Define science requirement for altitude range

9. Sampling Issues • Orbit options for IR, SW, GPS • SW sampling using radiance • SW orbit selection

10. Engineering perspective

12. Mission Drivers from Science that Need to be Closed • Separation of infrared and reflected solar • Do infrared and reflected solar measurements need to be coincident • Impacts: Mission architecture, number of observatories • Friday Status: • Need rationale for reflected solar in a sun-synch orbit (that related to science objectives) • Need description of mode of operation (benchmark mode and/or inter-calibration mode) • Need inter-calibration traceability analysis • Date Needed: June 1, 2009 • Number of observatories • Pending final results from science sampling study and verification from the science team • Impacts: Mission architecture, mission cost • Friday Status: Holding at 2 • Date Needed: June 1, 2009 • Instrument fields of regard • Pending results from all-sky benchmarking study to confirm infrared nadir-only pointing • Confirm wide ranging field of regard for solar spectrometers • Impacts: Mass, power, and complexity (gimbals and mirror mechanisms) • Friday Status: • Infrared: holding at off-axis nadir; require study of contamination effects on mirror polarization stability • Reflected solar: FOR holds for polar orbit, needs to be determined for sun-sync orbit • Date Needed: June 1, 2009

13. Mission Drivers from Science that Need to be Closed • Orbit selection (altitude, inclination, plane separation) • Pending final results from science sampling study and inter-calibration analyses • Impacts: Spacecraft propulsion, Atlas V DSS suitability • Friday Status: Inter-calibration approach suggests 83deg and 90deg orbits preferable • Date Needed: July 1, 2009 • Number of instruments • Pending science rationale for duplication of infrared and solar instruments • Impacts: Observatory mass and power, mission cost • Friday Status: Consider study to look at impact on sampling error from loss of earth-view data due to calibration/verification operations • Date Needed: July 15, 2009 • Infrared instrument accuracy • Definition of systematic error in radiance units, as a function of wavelength/wavenumber • Impacts: Determination of method to combine measures of various uncertainties • Friday Status: Waiting on derivation from climate signal estimation algorithm • Date Needed: July 15, 2009

14. Mission Drivers from Science that Need to be Closed • Consider polarimeter accommodation • Add science goal and update level 1 requirements • Need: Orbit (sun-synch or polar), instrument type, mode of operation • Impact:Orbit, spacecraft, payload, launch vehicle • Friday Status: New mission driver • Date Needed: June 15, 2009 • Requirement-based mission design • Update and, more importantly, begin to use flowdown of science objectives->Level 1 requirements->Level 2 requirements • Impact: All mission elements • Friday Status: New mission driver • Date Needed: June 1, 2009 • Track these action items at weekly science telecon?

15. Backup

16. CLARREO Mission Design Process L2 Measurement Requirements Update Payload Conceptual Design L1Science Objectives Update PEL Observatory Design Concept Bottoms-up Design Process Apply Technical Margins L1 Mission Requirements Update MEL Iterate until resulting design is feasible (meets requirements & doesn’t conflict w/ concept) Launch Vehicle Identification Mission Concept Iteration Complete (PPT Charts, Technical Allocation, MEL, Requirements, Mission Operations Concept) Milestone Events

17. The Science Driving CLARREO • The science driving the CLARREO mission is contained in two societal objectives. • Societal objective of establishing a climate benchmark: • The essential responsibility to current and future generations to put in place a benchmark climate record, global in its extent, accurate in perpetuity, tested against independent strategies that reveal systematic errors, and pinned to international standards on-orbit. • Societal objective of testing climate models: • The critical need for climate forecasts that are tested and trusted through a disciplined strategy using state-of-the-art observations with mathematically rigorous techniques to systematically improve those forecasts.

18. Draft Level 1 Science Objectives • Primary Objectives • Demonstrate capability to make decadal change observations necessary to derive cloud feedback • Demonstrate capability to make decadal change observations necessary to derive water vapor and lapse rate feedback • Demonstrate capability to make decadal change observations necessary to derive temperature and humidity responses • Secondary Objectives • Demonstrate capability to make decadal change observations necessary to derive snow and ice albedo feedback • Demonstrate capability to make decadal change observations necessary to derive land albedo change • Demonstrate capability to make decadal change observations necessary to derive vegetation index change

19. IR Measurement Requirement • CLARREO shall measure the nadir infrared radiance emission spectra of the Earth at top of atmosphere • over 3 years with • radiance level that corresponds to 0.1 K accuracy (3s confidence with SI-traceability) at 1000 wavenumbersTBR • 10 degree zonal annual average through global spatial scales • Rationale: • This accuracy is required for the detection of anticipated decadal climate change trends. High accuracy spectra across the full thermal infrared relevant to climate change will allow testing of climate models to understand their prediction accuracy by comparing emitted spectral radiance zonally and globally over decadal timescales to model outputs. It will also allow coverage of several years gap in the climate record while maintaining the ability to detect decadal climate change trends.

20. Solar reflected measurement requirement • CLARREO shall measure the solar spectral reflectance relative to the solar irradiance spectrum • over 3 years with • accuracy of 0.3% at 2 sigma confidence with SI-traceability TBR at • 10 degree zonal annual average through global spatial scales • Rationale: • This accuracy is required for benchmarking and intercalibration of other sensors for the detection of anticipated decadal climate change trends. High accuracy spectra across the full solar sprctrum relevant to climate change will allow testing of climate models to understand their prediction accuracy by comparing spectral reflectance zonally and globally over decadal timescales to model outputs. It will also allow coverage of several years gap in the climate record while maintaining the ability to detect decadal climate change trends

21. GNSSRO Measurement Requirement • CLARREO shall measure the refractivity through the Earth's atmosphere • over 3 years as a • 5º zonal mean (TBR) through global spatial scales, and at • monthly and annual time scales. • Tony M. draft: • Monthly-mean refractivity profiles0.1 K "equivalent" temperature precision (3-sigma)1 km vertical resolution0-40 km altitudePole-to-pole zonal average5-degree latitude binsUnbiased sampling (geophysics and LT)Systematic error < 0.05 K, all altitudesSystematic error determined in orbit tied to NIST standards

22. GNSSRO Measurement Requirement Rationale • Rationale: This scaling will achieve sufficient accuracy (0.01-0.02%, TBR) in an observed data type that is sensitive to vertical temperature structure between 5 km and 25 km (goal: 3 km – 45 km) above the surface, in enough detail such that this measurement can be compared to future measurements to reveal trends on decadal timescales. • GPSRO is sensitive to several key phenomena in climate change, namely thermal expansion of the troposphere, temperature change in the upper troposphere and stratosphere, and the migration of baroclinic zones in the atmosphere. This accuracy is required for the detection of anticipated decadal climate change trends