Climate Absolute Radiance and Refractivity Observatory (CLARREO)

The Story so Far…

David F. YoungNASA Langley Research CenterCLARREO Mission Study Lead

CLARREO Science Workshop

21-23 October 2008 Washington, DC

2Slide

Outline

• CLARREO and the Decadal Survey

• Basics of the mission

• CLARREO science questions

• Goals and structure of the Workshop

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Decadal Survey Missions

Near-Term Missions

Mid-Term Missions

Late-Term Missions

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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

5Slide

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

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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

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But, what is CLARREO?

8Slide

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

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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.

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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.

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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?

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How CLARREO Fits In

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CLARREO Science Questions

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Draft CLARREO Science Questions:Climate Forcing

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Draft CLARREO Science Questions:Climate Response

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Draft CLARREO Science Questions:Climate Feedbacks and Sensitivity

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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

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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

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Implementing CLARREO: Key Open Questions

Implementing CLARREO: Key Open Questions

ID Priority Questions

A 1 What climate trend components can benchmark radiances provide (clouds, water vapor, temp, etc)?

B,C 1 What climate trend components can be provided by intercalibration?

Can you intercalibrate filter radiometers (MODIS) to achieve climate accuracy?

D 2 Will the accuracy of the GNSS radio occultation enable us to determine the systematic errors in climate record?

E 2 What is the optimal way to "independently" validate the CLARREO data?

F 3 What is the required spatial/ temporal/angular coverage?

G 4 What is the spectral resolution required (IR and solar)? Note: decadal survey recommends 1 cm^-1 for IR, 15nm for solar.

H 4 What is the appropriate footprint size for optimal fingerprinting, inter-calibration, and validation?

I 4 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.

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Study Integration - LW Traceability Matrix

XXKey Studies

ContributingStudies

FOV Swath λ Resolutionλ Coverage Accuracy Noise ( )Orbit s / S C Pointing / S C Pointing Science Driver ( )km ( )km ( -1)cm ( -1)cm ( , 2K ) ( , 1K ) (#, , )Inclin Alt( , )Range Speed /Knowl Cont

Benchmark Spectral Radiance ( )Spectral Radiance Clear Sky X X X X X X ( )Spectral Radiance All Sky X X X X X X Surface Temperature X X X

Air Temperature Profile X X X Water Vapor Profile X X X ( , , ,Cloud Property C Z Tε(λ), )Deff X X X X

Infrared Aerosol Forcing X X Water Vapor Greenhouse Effect X X X Cloud Feedback X X X X X Water Vapor Feedback X X X X Lapse Rate Feedback X X X X

Calibration of Other Sensors, , CrIS IASI AIRS spectrometers X X X X X X X X X

/ / MODIS VIIRS AATSR imagers X X X X X X X/ Landsat ASTER imagers X X X X

CERES broadband X X X X X Geo Imagers X X X X X ( . . )Geo Sounders e g GIFTS X X X X X ( )Geo broadband GERB X X X X X

Science Driver

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CLARREO Benchmark Radiance Climate Model OSSEs

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 DecadalSpectral Signals

Climate ModelPredicted Change

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Test Climate Model Predicted Spectral SignalsTest Climate Model Predicted Spectral SignalsAgainst CLARREO Spectral Benchmarks Against CLARREO Spectral Benchmarks

Determine Climate Model PredictionDetermine Climate Model PredictionAccuracy, Needed ImprovementsAccuracy, Needed Improvements

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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 (ASIC3)

– Global Spacebased Inter-Calibration System (GSICS)

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CLARREO Solar Spectral IntercalibrationCLARREO 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 λ; 30 by 60km fov)

- Simulate CLARREO using MODIS surface/aerosol/cloud properties + radiative transfer theory (< 1nm λ; 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 CLARREO Calibrates CERES/VIIRSCERES/VIIRS

Climate Change

Cloud FeedbackCloud FeedbackObservationsObservations

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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

BeamsplitterBlackbody

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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

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Workshop Sessions

I. Introduction to CLARREOChair: David Young

II. Science Questions: Climate Benchmarking and S.I. TraceabilityChair: Jim Anderson

III. Science Questions: Climate Prediction and Climate Model Testing

Chair: Bill Collins

IV. SamplingChair: Daniel Kirk-Davidoff

V. Applied S.I. Traceability (and Instrument Incubator Proposals)Chair: John Dykema

VI. Inter-calibration of Operational Instruments Using CLARREOChair: Bruce Wielicki

VII. The Way ForwardChair: David Young

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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.

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Discussion Points

Climate Benchmarking and S.I. Traceability

Climate Prediction and Climate Model Testing

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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?

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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?

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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.

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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.