1. Climate Absolute Radiance and Refractivity Observatory (CLARREO) The Story so Far… David F. Young NASA Langley Research Center CLARREO Mission Study Lead CLARREO Science Workshop 21-23 October 2008 Washington, DC

2. Slide 2 Outline CLARREO and the Decadal Survey Basics of the mission CLARREO science questions Goals and structure of the Workshop

3. Slide 3 Decadal Survey Missions Near-Term Missions Mid-Term Missions Late-Term Missions

4. Slide 4 What is CLARREO? Climate Absolute Radiance and Refractivity Observatory One of the highest priority missions described in the NRC Earth Science Decadal Survey –Recommended in first group of 4 missions (“Tier 1”) A climate-focused mission –Foundation is on-orbit traceability of calibration –Long-term trend detection –Improvement and testing of climate predictions –Calibration of operational sensors –Details in following sessions

5. Slide 5 NASA / NOAA Roles for CLARREO NASA portion of CLARREO –Initiation of a climate record of SI traceable spectrally resolved radiance and atmospheric refractivity with the accuracy and sampling required to assess and predict the impact of changes in climate forcing variables on climate change. NOAA portion of CLARREO –Continuation of solar irradiance and earth radiation budget observations (TSIS and CERES) –Steps already underway CERES on NPP CERES and TSIS approved for NPOESS C1

6. Slide 6 Baseline Mission from the Decadal Survey 11 high-absolute accuracy instruments, 3 satellites, 3 launches for $200M 90° polar orbits for diurnal sampling Redundant IR spectrometers on each satellite –200 - 2000 cm-1 with 1 cm-1 resolution –Nadir viewing with ~100 km FOV –Accuracy goal: 0.1 K (3  ) GPS radio occultation receivers on each satellite Solar spectrometers on third satellite –300 - 2000 nm with 15 nm resolution –Accuracy goal: 3 parts per 1000

7. Slide 7 But, what is CLARREO?

8. Slide 8 Defining CLARREO NASA has formed a team to complete Pre-Phase A studies to define the CLARREO mission The study plan represents an integrated strategy that engages climate scientists, modelers, satellite instrument teams and calibration experts from: - NASA LaRC, GSFC, and JPL - U.C. Berkeley / GISS / GFDL - Harvard University - University of Wisconsin-Madison - Laboratory for Atmospheric and Space Physics - Contributing, but not funded: National Institute of Standards and Technology Begin by defining the societal objectives and key science questions to be addressed by CLARREO

9. Slide 9 CLARREO Societal Objectives Establishment of a climate benchmark: The essential responsibility to present 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. Development of an operational climate forecast that is tested and trusted through a disciplined strategy using state-of-the-art observations with mathematically rigorous techniques to systematically improve those forecasts.

10. Slide 10 CLARREO Imperative Initiate an unprecedented, high accuracy record of climate change that is tested, trusted and necessary to provide sound policy decisions. Initiate a record of direct observables with the high accuracy and information content necessary to detect long term climate change trends and to test and systematically improve climate predictions. Observe the SI traceable spectrally resolved radiance and atmospheric refractivity with the accuracy and sampling required to assess and predict the impact of changes in climate forcing variables on climate change.

11. Slide 11 CLARREO Science Questions Given the rapid increase in climate forcing from carbon release, how is the Earth 痴 climate system changing? Recognizing the impact on both scientific understanding and societal objectives resulting from the irrefutable, high accuracy, SI traceable Keeling CO2 record, what measurements obtained from space would constitute an analogous high accuracy, SI traceable climate record defining the global response of the climate system to the anthropogenic and natural forcing?

12. Slide 12 How CLARREO Fits In

13. Slide 13 CLARREO Science Questions

14. Slide 14 Draft CLARREO Science Questions: Climate Forcing

15. Slide 15 Draft CLARREO Science Questions: Climate Response

16. Slide 16 Draft CLARREO Science Questions: Climate Feedbacks and Sensitivity

17. Slide 17 NASA Planning for CLARREO Engage community –Decadal Survey –First workshop in July 2007 to provide community feedback –Current Workshop Pre Phase A studies (May 2008 - September 2009) –Define primary science objective from the DS –Identify gaps from workshop –Directed studies focused on key cost drivers –Direct involvement of climate modeling community Technology Risk Reduction –Instrument Incubator program used to address key technology development

18. Slide 18 Goals of FY08 - FY09 Studies Define clear mission requirements to ensure that NASA’s performance objectives are met, future costs are contained, and delays are minimized. Respond to several key areas of concern - CLARREO needs clearer science requirements - CLARREO needs more buy-in from the climate modeling community that it is intended to serve. - The ESD cost estimate for CLARREO is much higher than the DS estimate Working towards a potential Mission Concept Review in late FY09 / early FY10. Earliest possible launch within current budget is 2017

19. Slide 19 Implementing CLARREO: Key Open Questions IDPriority Questions A1 What climate trend components can benchmark radiances provide (clouds, water vapor, temp, etc)? B,C1 What climate trend components can be provided by intercalibration? Can you intercalibrate filter radiometers (MODIS) to achieve climate accuracy? D2 Will the accuracy of the GNSS radio occultation enable us to determine the systematic errors in climate record? E2 What is the optimal way to "independently" validate the CLARREO data? F3 What is the required spatial/ temporal/angular coverage? G4 What is the spectral resolution required (IR and solar)? Note: decadal survey recommends 1 cm^-1 for IR, 15nm for solar. H4 What is the appropriate footprint size for optimal fingerprinting, inter-calibration, and validation? I4 What is the spectral range required for infrared? Using the Decadal Survey, recommendations from the July 2007 Workshop, and community feedback the following key set of questions were identified that must be answered by trade studies before a mission can be rigorously defined.

20. Slide 20 Study Integration - LW Traceability Matrix X X Key Studies Contributing Studies Science Driver

21. Slide 21 CLARREO Benchmark Radiance Climate Model OSSEs CLARREO Mission Objectives include monitoring of climate change using SI-traceable spectral radiance benchmarks at high absolute accuracy Approach –Climate OSSE using CLARREO simulator in climate model for decadal change –NCAR, GFDL, and NASA GISS climate models key participants - IR clear-sky already published, IR all-sky underway, Solar is new. Key benchmark radiance trade studies: - Add CLARREO simulators to major climate models to test CLARREO decadal change spectra signals. - Verify accuracy of simulators using monthly mean properties versus individual time steps. The first use of the OSSE concept with decade to century climate models Simulate Decadal Spectral Signals Climate Model Predicted Change Test Climate Model Predicted Spectral Signals Against CLARREO Spectral Benchmarks Determine Climate Model Prediction Accuracy, Needed Improvements

22. Slide 22 CLARREO and Intercalibration Goals consistent with recent reports on satellite calibration requirements: –NASA / NOAA / NIST / NPOESS Satellite Climate Calibration Workshop (Ohring et al., 2005) –Global Climate Observing System (GCOS) international report –Achieving Satellite Instrument Calibration for Climate Change (ASIC 3 ) –Global Spacebased Inter-Calibration System (GSICS)

23. Slide 23 CLARREO Solar Spectral Intercalibration CLARREO Mission Objectives require that climate variables remotely sensed from space using reflected solar radiation be at accuracies sufficient for detection of decadal change. - Accuracy requirements for decadal change taken from previous reports - A potential method to achieve climate accuracy is for CLARREO to calibrate other sensors. Three approaches –Climate OSSE using CLARREO simulator in climate model for decadal change - Simulate MODIS and VIIRS using Schiamachy in orbit spaceborne spectrometer (< 1nm  ; 30 by 60km fov) - Simulate CLARREO using MODIS surface/aerosol/cloud properties + radiative transfer theory (< 1nm  ; 1km fov) There are several key intercalibration studies - Does spectral response of filters change enough over time to alias climate change (e.g. MODIS, VIIRS)? - Can CLARREO detect and correct spectral response changes of other sensors? - Can CLARREO achieve sufficient space-time- angle sampling for intercalibration of other sensors? CLARREO 600km orbit Aqua MODIS, CERES 705km orbit CLARREO Calibrates CERES/VIIRS Climate Change Cloud Feedback Observations

24. Slide 24 CLARREO Technology Investments A New Class of Advanced Accuracy Satellite Instrumentation (AASI) for the CLARREO Mission (Wisconsin / Harvard) –Develop and demonstrate key technologies necessary to measure IR spectrally resolved radiances with ultra-high accuracy (<0.1 K 3 sigma) brightness temperature (at scene temperature) for CLARREO. –Technologies include: On-orbit Absolute Radiance Standard including Miniature Phase Change Cells On-orbit Cavity Emissivity Module using quantum cascade laser (QCL) and heated halo reflection On-orbit Spectral Response Module using QCL CORSAIR: Calibrated Observations of Radiance Spectra from the Atmosphere in the far-InfraRed (NASA Langley) –Performance goals are 0.1 Kelvin absolute radiometric accuracy (3 standard deviations) over a spectral range from 200 to 2000 cm -1 with a resolution of 1.0 cm -1. –Technologies include IR detector elements sensitive from 15 to 50 µm that do not require cryogenic cooling SI traceable blackbody radiance standards for wavelengths beyond 15 µm Robust optical beamsplitters with continuous high efficiency over the full 200 to 2000 cm -1 spectral range A Hyperspectral Imager to Meet CLARREO Goals of High Absolute Accuracy and On-Orbit SI Traceability (LASP) –Improve radiometric accuracy of visible & Near- Infrared hyperspectral imaging needed for Earth climate studies via cross-calibrations from spectral solar irradiances. –Enable on-orbit end-to-end spatial/spectral imager radiometric calibrations and degradation tracking with 0.2% SI-traceable accuracy Detector Beamsplitter Blackbody

25. Slide 25 Status Studies formulated and begun in June 2008 Draft of CLARREO Science Questions nearly complete Preparing for development of Level 1 requirements Planning for Mission Concept Review in 2009

26. Slide 26 Workshop Sessions I.Introduction to CLARREO Chair: David Young II.Science Questions: Climate Benchmarking and S.I. Traceability Chair: Jim Anderson III.Science Questions: Climate Prediction and Climate Model Testing Chair: Bill Collins IV.Sampling Chair: Daniel Kirk-Davidoff V.Applied S.I. Traceability (and Instrument Incubator Proposals) Chair: John Dykema VI.Inter-calibration of Operational Instruments Using CLARREO Chair: Bruce Wielicki VII.The Way Forward Chair: David Young

27. Slide 27 Workshop Goals Discuss and refine the CLARREO science objectives Present results from on-going science trade studies for community comment Define and refine the links between the identified science objectives and the measurement requirements Present CLARREO-related Instrument Incubator Proposal Selections Identify requirements for technological development to enable mission success Identify studies needed to further the readiness of the CLARREO mission.

28. Slide 28 Discussion Points Climate Benchmarking and S.I. Traceability Climate Prediction and Climate Model Testing

29. Slide 29 Discussion Points Sampling The sampling rate requirement for accurate measurement increase as the length of the averaging period decreases, and as the statistical order of the measurement increases. How can we most clearly and concisely express the trade-off between the number of CLARREO orbiters and the attainment of CLARREO mission science goals? What metrics of CLARREO science value should be used to determine the optimal field of view for the IR and visible instrument, and what weight should they be given? How does the additional variable of solar zenith angle affect the sampling problem for the creation of benchmark observations of solar reflectance? Applied S.I. Traceability What further technical advances are necessary to make each IIP flight worthy? What systematic errors are known for IR, SW and how do we quantify them?

30. Slide 30 Discussion Points Inter-calibration of Operational Instruments What spectral properties (e.g. coverage, resolution, sampling) are required of CLARREO for accurate intercalibration of operational IR imagers and sounders, solar and IR imagers, and broadband instruments like CERES? What combination of CLARREO instrument noise performance and footprint size is required of CLARREO for accurate IR and solar reflected intercalibration? What is the right time interval for calibration at climate accuracy? Can we detect and correct spectral changes from in orbit optics contamination? What is the requirement for in-situ/aircraft validation of CLARREO itself?

31. Slide 31 CLARREO - Why Now? The timing of the CLARREO mission (why now?) is a result of recent advances in a wide range of scientific, metrology, and technological research. These recent advances include: –a clearer understanding of the value of decadal change observations at high accuracy in providing the critical testing ground for the accuracy of climate model predictions. –a clearer understanding of the level of uncertainty in climate forcings and feedbacks, –improved accuracy of infrared blackbody sources using phase change temperature measurements as part of highly accurate deep well blackbodies. –improved accuracy of spaceborne spectral and total solar irradiance using active cavity absolute detectors (e.g. SORCE) –factor of 1000 improved sensitivity of active cavity detectors through cryogenic cooling (including mechanical coolers) to low temperatures. –new methods at national physics laboratories developed to increase the accuracy of solar wavelength standards by an order of magnitude. ( SIRCUS ) –greatly increased experience with more accurate high spectral resolution mid-infrared spectrometers and interferometers for temperature, water vapor, and cloud sounding (AIRS, IASI, CrIS spaceborne instruments as well as AERI, NAST-I, HIS, and Intessa ground and airborne instruments. –the first successful Far Infrared interferometer flights on a high altitude balloon (FIRST) – greatly improved methods and understanding of how to accurately intercalibrate instruments in orbit including interferometers, imagers, and broadband radiation budget instruments.

32. Slide 32 CLARREO - Why Now? These advances combine to enable CLARREO to be a completely new type of climate mission. A mission focused on accuracy at decade time scales through two complementary methodologies: spectral radiance benchmarks, and intercalibration of other orbiting sensors. A mission focused on high spectral resolution and broad spectral coverage throughout the solar and infrared spectrum that drive the Earth’s climate energy system and climate change. A mission able to leverage its capability across a wide range of climate science disciplines, and satellite earth observing systems. CLARREO will be the first mission capable of providing an anchor at decade time scales to a climate observing system which is currently an accident of international weather and research observing systems. Every year we delay is a year lost in beginning that climate observing system.