# Presentation: 475293

## CLARREO Pre-Phase A StudyJPL Study ActivitiesTom Pagano, Eric Fetzer, Kevin Bowman, Alex Ruzmaikin, Hartmut Aumann, Samantha Infeld

- CLARREO Pre-Phase A StudyJPL Study ActivitiesTom Pagano, Eric Fetzer, Kevin Bowman, Alex Ruzmaikin, Hartmut Aumann, Samantha Infeld

- California Institute of Technology
- Jet Propulsion Laboratory
- tpagano@jpl.nasa.gov
- May 1, 2008

- AIRS Water Vapor
- Isosurfaces

## JPL Study Team

- Hartmut Aumann:  AIRS Climate Science
- Kevin Bowman:  TES Climate Science
- Mous Chahine:  AIRS Science
- Eric Fetzer:  AIRS Water Vapor
- Samantha Infeld:  Mission Systems Engineering
- Tony Mannucci:  GPS Science
- Tom Pagano:  Instrument Calibration
- Alex Ruzmaikin:  Climate Science
- Joao Teixiera:  Climate Model Validation
- Duane Waliser:  Climate Model Assessment

## JPL Agenda

- JPL Perspective 	Pagano
- Radiance Tasks
- Simulated CLARREO IR Data SetsUsing AIRS and IASI
- Instrument Error Analysis
- Cross-calibration Sensitivity
- Science Tasks	Fetzer
- Science Questions
- Current Capabilities
- Future needs from CLARREO
- Modeling Tasks	Bowman
- Relation of OSSE’s to Measurement Requirements

***Also present from JPL:  Samantha Infeld and Alex Ruzmaikin***

## JPL CLARREO Team Perspective

**CLARREO is a great idea.**
**JPL manages Aqua AIRS and Aura TES experiments**
- Both hyperspectral infrared instruments
**AIRS and TES now used for climate science**
- Model Validation, Process Studies, Trending
- AIRS radiances are the only climate data record from AIRS today.  Geophysical products not far behind (2 years)
- AIRS, CrIS and IASI Calibration Exceptional and Meet Majority of CLARREO MW/LW Measurement requirements with better coverage and resolution.
**Plan to continue climate observations using CrIS & IASI**
- NASA NPP Sci Team / PEATE to continue work with CrIS & IASI
**Hyperspectral sounders will be around “in perpetuity”**
- Low risk of NOAA discontinuing them because they provide real forecast impact and NOAA  has a high interest in climate observations
- Additional Hardware Cost to NASA:  **Free**
**CLARREO is a great idea**
**CLARREO must address the key uncertainties in climate science**
- What are the CLARREO science questions (not measurement requirements)?
- The question is not “What can we do with CLARREO”, but “What can CLARREO do for us”?
- Can we phrase a question that if answered will improve model representation of cloud and water vapor feedbacks?  See Fetzer “Testable Hypotheses”

## AIRS Climate Data Products

***Global:  Day & Night, Pole to Pole, Land & Oceans, Cloudy & Clear, Daily***

## AIRS Products Validation Status

- *Necessary Products are required to retrieve accurate temperature profiles (1K/km) in all condition
- **Product not yet available in AIRS Level 2 Files.  Products will be available in Version 6

##  Sounder Constellation in Place Continuously from 2002 onward

**AIRS**
**1:30 PM Orbit**
**14 km GSD**
**±49.5° Swath**
**Aqua: 2002**

**IASI**
**10:30 AM Orbit**
**12 km GSD**
**±49° Swath**
**MetOp 2007**

**TES on Aura**
**1:30 PM Orbit**

**NPP**

**C1**

**C3**

**C2**

**CrIS**
**1:30 PM Orbit**
**14 km GSD**
**±48.3° Swath**
**NPP: 2010**
**C1: 2013 C3: 2020**

**NPOESS**
**5:30 AM**
**C2: 2016**
**CrIS De-Manifested**

- Sounder NEdT Comparison

- Performance
- Comparable for
- AIRS, CrIS and IASI

**Notes:**
The timeframe for observations of the current and planned sounder suite ranges from 2002 to the distant future.  In the near future we could be very fortunate to have four hyperspectral instruments simultaneously operating in orbit.  Beyond this the international operational sounder system is in place.  Please note that CrIS on the NPOESS C2 Spacecraft was de-manifested.

## AIRS/CrIS and IASI Provide 4 Points in Diurnal Cycle

- AIRS:  Aqua: 13:30, 1:30TES:  Aura: 13:30, 1:30
- CrIS:  NPOESS C1 and C3: 13:30, 1:30
- IASI:  MetOp, 9:30, 21:30
- CrIS:  NPOESS C2 (Demanifested): 5:30, 17:30

- C

- A

- C

- A

- I

- I

- C

- C

- A

- C

- C

- I

- Diurnal Cycle of SST

*Recommendation made to “NRC Panel on Options to Ensure the Climate Record from the NPOESS and GOES-R Spacecraft” that loss of CrIS on C2 will impact ability to study diurnal cycle (June, 2007)*

**Notes:**
The Sounder Constellation covers 4 points in the diurnal cycle.  CrIS or CLARREO on the NPOESS C2 Spacecraft would provide two additional points in the diurnal cycle, key for some cycles like the one shown here for SST.  Differences calculated using AIRS and IASI data match the in-situ values shown in the graph well.

## AIRS/CrIS show high accuracy(Based on pre-flight test and estimates)

**AIRS Accuracy < 0.2K 3********, 250K**

**CrIS Accuracy < 0.2K 3********, 287K**

- Requirement

**Requirement**

**With Linearity****Correction**

**Predicted**

- T. Pagano
- ITT Estimates converted to T. Edge effects not shown.

**CLARREO Requirement**

**CLARREO Requirement**

- Pagano, IEEE TGRS, 2007
- Pagano, Proc ITOVS, 2003
- Pagano, AGU 2007
- Pagano, SPIE 2008 (TBD)

**NIST Traceable**

## Radiometric Accuracy and Stability Validation match Observational Accuracy

**Scanning HIS Validates Rad Accy to <0.2K – Tobin, Revercomb (UW)**

**RTGSST Validates Radiometric Stability <10mK/Y – H. Aumann (JPL)**

***Reference:  JGR, ******VOL. 111, April 2006***

- AIRS

***Given perfect Accuracy stability is ESSENTIAL to Climate observations***
***to differentiate instrument variability from scene variability***
***Validated against NIST Traceable Buoys***

**Notes:**
In our opinion it was not enough to verify accuracy and stability pre-flight.  Scientist require independent validation of the data.  We currently have over 5 billion spectra acquired from AIRS; the large number facilitates validation.  Comparison with the interpolated Buoy RTG Sea Surface Temperature network verifies stability to be better than 8mK.  Absolute accuracy was validated using the scanning HIS aircraft instrument.  Spectral accuracy is validated using atmospheric spectroscopy.  AIRS shows less than 1ppm/year drift with frequency knowledge better than 1ppm.

## Cross-Calibration of AIRS and IASI made with tropical clear data sets

**Clear AIRS**
**74,841**
**Clear IASI**
**40,407**
******x < 10 km**
**Night**
**719**
******t < 5 hrs**
**309**

**3 Million AIRS**
**Total Obs/Day**

## AIRS and IASI Warm Radiometry Agree in Window Regions to less than 50 mK

**Mean Difference: 0.0356 K**
**Standard Deviation: 0.1319 K**

**Mean Difference: -0.0063 K**
**Standard Deviation: 0.1961 K**

- Longwave Window

- Shortwave Window

**Warm (~290K), Uniform, Clear**
**No Spectral Correction, No PC Filtering**

**AIRS-IASI (K)**

**AIRS-IASI (K)**

**Cross-calibration of Sounder Radiometry Not Required by CLARREO.**
**We will test how well CLARREO cross-calibrate using this technique.**

## Fractional Clear Drops Fast with Spatial Resolution 

- 1J. Krijger et. al, The effect of sensor resolution on the number of cloud-free observations from space, Atmos. Chem. Phys. Discuss., 6, 4465-4499, 2006, _[www.atmos-chem-phys-discuss.net/6/4465/2006](http://www.atmos-chem-phys-discuss.net/6/4465/2006)_

- 1 km, 32%

- 100 km, 2%

- 15 km, 12%

- Fraction Clear vs Area
- For 1K Cloud Contamination1

**Notes:**
We have found that validation is an essential part of our climate observational program.  What makes validation work is the ability to find sufficient clear samples.  The number drops by at least a factor of 5 going from 15 km to 100 km.   The numbers shown here are a factor of about 5 larger than needed for < 0.2K cloud contamination.  Another factor in the validation and cross-comparisons is the wide swath of the sounders and their good NEdT.

## Cross-Calibration and Comparison Successful with Imagers and Sounders

**AIRS-MODIS/HIRS ****Trend in Radiometric Calibration ****Dome Concordia**

**MODIS Bias ~ 1K**

***Shift in MODIS Calibration Algorithm V4 to V5***

**HIRS Stable**

**S. Broberg, Evaluation of AIRS, MODIS, and HIRS 11 micron brightness temperature difference changes from 2002 through 2006, SPIE 6296-22, August 2006**

**Must Calibrate**
**Temperature **
**Dependence**

**Notes:**
The high accuracy of AIRS has allowed cross comparison with other instruments including MODIS, HIRS and IASI.  The stability and accuracy of AIRS allowed us to see a significant change in the MODIS calibration due to a change in the Level 1B algorithm.  No change was observed in HIRS for the same time period.  A single comparison with IASI for a uniform scene at Dome C showed virtually no detectible bias compared to AIRS.

## AIRS Radiance Trending Analysis

- Linear fit:    -30  42 mK/y

- Nonlinear trend insignificant  for monthly data, significant for 8-day data

- A. Ruzmaikin

- Difficulty with Trends:  Nonlinear
-  Linear fits and averaging could be misleading
- Signed forcing: anthropogenic (+), volcanic (-), solar (), ...
- Interlock with natural variability -- 2-order fingerprint may be insufficient
- Data must have high time cadence (1 day) and spatial resolution (≤ 10 km) to allow successful data analysis over mission life (< 10 yrs) using advanced nonlinear methods

## Spatial or Temporal Averaging Will Reduce Sensitivity to Clouds

**10-day average**

**Without time average**

**10-day average**

**Without time average**

**High clouds got washed out!**

**King-Fai, Duane Waliser, Yuk Yung, CalTech**

## Cloud variability (scene noise) masks calibration errors in high contrast scenes 

- Spatial Response Function
- Must be well known
- Channel 774, FP 70

- AIRS-MODIS
- Non-uniform Scene

- Corrected
- 0.57K

- Uncorrected
- 4.2K

- Simple
- Correction
- 2.26K

**Higher Spatial Resolution CLARREO (<5 km) will**
** ****Improve characterization of biases in high contrast scenes**
** ****Will improve SNR of cross-comparisons**
** ****Will improve accuracy of validation (more samples per aircraft overpass)**

- D. Eliott, et. al, “The Impact Of the AIRS Spatial Response On Channel-To-Channel
- and Multi-Instrument Data Analyses”, Proc. SPIE, 6296-01 (2006)

**Notes:**
Spatial response limits ability to cross-calibrate in non-uniform scenes.  Knowledge of the spatial response improves the comparison significantly, but not to the levels required to reduce the noise for sufficient SNR for comparison.

## CLARREO Measurement Ideas

**CLARREO is needed to advance science and improve cross-calibration**
- CLARREO must provide an advancement in observational performance beyond the current sounders
- Low spatial resolution reduces sensitivity to phenomenon affecting climate signatures; cloud, water vapor and temperature variability (correlations)
- Narrow swath reduces global coverage and sampling
- Both of these will limit CLARREO’s ability to do climate science and cross-calibration
- Going to great expense to achieve diurnal cycle and sampling
- Multiple satellites will greatly increase program costs
- Sounders cover 4 points in diurnal cycle
- Multiple instruments will not reduce systematic errors (especially if built the same and calibrated by the same equipment)
- Cost of higher performance need not be high
- Use of modern technologies (e.g. Large Format Array HgCdTe)
- Use of technology developed in industry on GOES HES and NASA IIP
- Overall program would be more robust if we can
- Start with a single satellite.  Eventually we will move to constellations.
- Improve spatial resolution (better than sounders) and wide swath
- Single instruments rather than redundant.

## AIRS Water VaporWide Swath gives Daily Global Coverage

- This one feature has made AIRS data invaluable for cross-calibration and climate science products (Level 3 Products)

## Task Summary: Generate and Analyze CLARREO simulated radiance data sets

- Generate Simulated CLARREO Climate Data Product
- AIRS and IASI Data
- ~6 years, ~14 km
- Nadir Only
- Aggregate to 152 x 90, 602 x 90, 902 x 90 km.
- Repeat/Combine with IASI Data
- ~12 Months, ~ 12 km
- Nadir Only
- Aggregate to 152 x 90, 602 x 90, 902 x 90 km
- Generate Clear Data Subset of Aggregates
- Science Assessment
- Is spatial/temporal coverage sufficient to trend stability?
- Extrapolate to full-up CLARREO suite by analysis
- Verify ability to cross-calibrate with IASI and MODIS
- What resolution is best suited for cross-calibration?
- Trend Assessment

## Slide 21