# Presentation: 424984

## Atmospheric Infrared Sounder (AIRS) 

**Atmospheric Infrared Sounder (AIRS) **
**validation with S-HIS **
**(Scanning High-resolution ****Interferometer Sounder)**

- _Hank Revercomb_, David C. Tobin, Robert O. Knuteson, Fred A. Best, William L. Smith*, Paul van Delst, Daniel D. LaPorte, Scott D. Ellington, Mark W.Werner, Ralph G. Dedecker, Ray K. Garcia, Nick N. Ciganovich, H.Benjamin Howell**University of Wisconsin, SSEC ***** NASA LaRC**
- Optical Society of America, ORS/FTS Topical Meeting, Quebec City, 3-6 February 2003

## Calibration and Validation for IR radiance observationsare now concerned with tenths of K, not degrees K !

**Calibration and Validation for**** IR radiance observations****are now concerned with **_**tenths of K, not degrees K**_** !**
**High Spectral Resolution is an important part of the reason**

##  New Era: Spaceborne High-resolution IR  AIRS/CrIS/IASI (LEO) to GIFTS/HES (GEO)

**CrIS**

**CO****2**

** ****CO**

**CH****4**

**CO****2**

**O****3**

**N****2****O**

**N****2****O**

**CO****2**

**H****2****O**

**H****2****O**

**AIRS/CrIS**

**GIFTS**

**GOES Sounder**

**IASI**

## TOPICS

-  _AIRS_
-  _Scanning-HIS_
-  _Radiance Validation_:
-  Oklahoma, ARM UAV “Grand Tour”(SHIS on Proteus at 15 km, 16 Nov 2002)
-  Gulf of Mexico, Terra/Aqua 2002      (SHIS on ER2 at 20 km,        21 Nov 2002)
-  _Summary_

## AIRS-AMSU-HSB

**AIRS-AMSU-HSB**
**Atmospheric Infrared Sounder**
**Advanced Microwave Sounding Unit**
**Humidity Sounder for Brazil**

## AIRS 4 May 2002 Launch

**AIRS****14 June 2002**

- Calculated

- NASA Aqua

**Notes:**
This is just a few pictures of AIRS.  The one on the top left is of AIRS just prior to integration onto the Aqua sensor suite.  AIRS is a grating spectrometer.  The one on the right is the Aqua sensor suite at TRW undergoing a “shake” test.  The one on the bottom left is a sample simulated spectrum.  X-axis is in wavenumbers.  The spectral resolving power (delta v over v) is 1200.

## AIRS Global Coverage20 July 2002 Ascending, LW Window

**AIRS Global Coverage****20 July 2002 Ascending, LW Window**

**Notes:**
This shows the ascending data (day-time) for the current AIRS “focus day” of 20 July 2002.  The image is of a longwave window channel brightness temperature (using a GOES colormap), along with various sample spectra.

We’ve had global observations of high spectral resolution before (IRIS and IMG), but they were not really atmospheric profile sounders.  The AIRS data is very clean, and the applications are numerous.  This is what many of us have been waiting for, and working towards for many years.  There are many un-tapped opportunities: SO2 detection from volcanoes, the blue-spike fire detection, new cloud detection techniques, low level inversion detection for severe weather, new spectroscopy investigations, climate change signatures, ... 

## EMISSIVITY AND NONLINEARITY MEASURED PRE-FLIGHT

**Small corrections (******** 0.1-0.2 %)       Uncertainty <0.1% expected**

- (Tom Pagano, AIRS Project Manager)

## SCAN ANGLE DEPENDENCE MEASURED & MODELED PRE-FLIGHT

_**Good Agreement**_**: Expect <0.1 K residual errors after correction**

- (Tom Pagano, AIRS Project Manager)

## Scanning HIS with Calibration Summary

**Scanning HIS ****with Calibration Summary**
**& 1st Uplooking Spectrum**

##  UW Scanning HIS:  1998-Present(HIS: High-resolution Interferometer Sounder, 1985-1998)

**	**_**Characteristics**_
**Spectral Coverage:**  3-17 microns
**Spectral Resolution:**    0.5 cm-1
**Resolving power:**      1000-6000
**Footprint Diam:** 1.5 km @ 15 km
**Cross-Track Scan:** Programmable
-   including uplooking zenith view

** ****Radiances for ****      Radiative Transfer**
** ****Temp & Water Vapor ****      Retrievals**
** ****Cloud Radiative Prop.**
** ****Surface Emissivity & T**
** ****Trace Gas Retrievals**

_**Applications:**_

## SSEC Scanning HIS on 1st ARM-UAV Mission with Proteus, October 2002

**S-HIS**** scans cross-****track downward &****looks upward**

## RSSTHBBTABBTRFLHBB ABB

- TABB = 260K, THBB = 310K

**RSS****T****HBB****T****ABB****T****RFL********HBB** ******ABB**

## Scanning-HIS Radiometric Calibration Budget for 11/21 case

- TABB = 260K, THBB = 310K

## Scanning-HIS Radiometric Calibration Budget for 11/16 case

- TABB = 227K, THBB = 310K

## Scanning-HIS LW/MW and MW/SW Band Overlap

**Scanning-HIS LW/MW and MW/SW Band Overlap**

- LW HgCdTe band

- MW HgCdTe band

- SW InSb band

- LW/MW overlap

- MW/SW overlap

- Radiance, mW/m2 sr cm-1

## Scanning-HIS LW/MW and MW/SW Band Overlap11-16-2002

**Scanning-HIS LW/MW and MW/SW Band Overlap**11-16-2002

- LW HgCdTe band

- MW HgCdTe band

- SW InSb band

- LW/MW overlap

- MW/SW overlap

## S-HIS zenith and cross-track scanning Earth views 11-16-2002 from Proteus @ ~14km

## Observed and Caculated zenith views from Proteus @ ~14km

- Calculated
- Observed

- Calculation based on 18Z ECMWF analysis, with 0.0004 cm H2O above 14km

## Radiance Validation of AIRS with S-HIS

**Radiance Validation ****of AIRS with S-HIS**

##                 AIRS / SHIS Comparisons

-                 **AIRS / SHIS Comparisons**
-  A detailed comparison should account for:
-  instrumental noise and scene variations
-  Different observation altitudes (AIRS is 705km, SHIS is ~20km on ER2, ~14km on Proteus)
-  Different view angles (AIRS is near nadir, SHIS is ~±35deg from nadir)
-  Different spatial footprints (AIRS is ~15km at nadir, SHIS is ~2km at nadir)
-  Different spectral response (AIRS =/1200, SHIS =~0.5 cm-1) and sampling

- SHIS and AIRS SRFs

##           AIRS / SHIS Comparison steps

**          ****AIRS / SHIS Comparison steps**
- . _Average SHIS data within AIRS FOV(s) & compare_
-  No attempt to account for view angle, altitude, spectral differences.
- . _Compare Residuals from calculations_:                                 (obs-calc)SHIS to (obs-calc)AIRS
-  SHIS and AIRS calcs each done at correct altitudes,   view angles, spectral resolution and sampling.
-  Monochromatic calcs done using same forward model,  atmospheric state, and surface property inputs.
- . _Difference Residuals: Spectral Resolutions made similar_
-  valid comparison except for channels mainly sensitive to   upper  atmosphere, above proteus altitude

## ARM UAV Campaign

- MODIS cloud mask
- (green is confident clear)

**ARM UAV Campaign**
- 19:24 UTC (daytime), Lamont Oklahoma
- 11/16/2002

- Proteus flight track

- Aqua Sub-satellite track

- time coincidence
- (near ARM site)

- AIRS and SHIS
- 12m brightness temperatures

- 280K

- 289K

**ARM offers good atmospheric knowledge**

## MODIS 12 m Band Brightness Temperatures and selected AIRS FOVs

**6 AIRS FOVs used in the following comparisons**

- MODIS 12 m Band Brightness Temperatures and selected AIRS FOVs

## “comparison 0”

_**“**__**comparison 0”**_
- 6 AIRS FOVs, 601 SHIS FOVs, PC filtering

- AIRS
- SHIS

- S-HIS Spectrum Nyquist sampled without gaps

## “comparison 0”

- AIRS
- SHIS

_**“**__**comparison 0”**_
- 6 AIRS FOVs, 601 SHIS FOVs, PC filtering

## Terra/Aqua Experiment-2002

- 0.65mm     1.90mm    3.74mm   11.01mm     RGB

- MAS Quicklooks flight leg 5

- MODIS cloud mask
- (green is confident clear)

- ER2 Flight track

**Terra/Aqua Experiment-2002**
- 19:40 UTC (daytime), Gulf of Mexico11/21/2002

- Aqua Sub-satellite track

- time coincidence

## MODIS 12 m Band Tbs(K) & near-nadir AIRS FOVs

- MODIS 12 m Band Tbs(K) & near-nadir AIRS FOVs

## MODIS 12 micron Band & near-nadir AIRS FOVs

**8 AIRS FOVs used in the following comparisons**

- 1 Degree

## PC Noise Filtering of SHIS and AIRS

- _PC Noise Filtering of SHIS and AIRS_
- noise normalized, 20 PCs per band

- Original AIRS
- PC Filtered AIRS

- Original SHIS
- PC Filtered SHIS

- granule 196, scan lines 113, 114, 115;
- rows 45, 46.  Bad_Flag==0

- 41 nadir spectra along flight line #5
- (note: 2km spatial resolution adds real scene variability)

## “comparison 0”

_**“**__**comparison 0”**_
- 8 AIRS FOVs, 448 SHIS FOVs, PC filtering

- AIRS
- SHIS

## “comparison 0”

_**“**__**comparison 0”**_
- 8 AIRS FOVs, 448 SHIS FOVs, PC filtering

- S-HIS Spectrum Nyquist sampled without gaps

## Atmospheric Profiles

## AIRS Compared to S-HIS, 21 Nov 2002

- “Comparison 2”

- wavenumber

_**AIRS**_** Compared to **_**S-HIS**_**, 21 Nov 2002**

- AIRS & S-HIS Obs-Calc

- _Black_ is Calculation

## AIRS Compared to S-HIS, 21 Nov 2002

- “Comparison 2”

- wavenumber

_**AIRS**_** Compared to **_**S-HIS**_**, 21 Nov 2002**

- AIRS & S-HIS Obs-Calc

- _Black_ is Calculation

## AIRS Compared to S-HIS, 21 Nov 2002

- “Comparison 2”

- wavenumber

_**AIRS**_** Compared to **_**S-HIS**_**, 21 Nov 2002**

- AIRS & S-HIS Obs-Calc

- _Black_ is Calculation

**Different viewing angle make daytime comparisons less accurate**

## Small Spectral Shift (3% of resolution) in AIRS Module-05 identified from S-HIS Validation 

- Small Spectral Shift (3% of resolution) in AIRS Module-05 identified from S-HIS Validation

## “Comparison 2” (21 November 2002) Excluding channels strongly affected by atmosphere above Proteus

- (AIRSobs-AIRScalc)-
-    (SHISobs-SHIScalc) (K)

- “Comparison 2” (21 November 2002) Excluding channels strongly affected by atmosphere above Proteus

## “Comparison 2” (21 November 2002) Excluding channels strongly affected by atmosphere above Proteus

- (AIRSobs-AIRScalc)-(SHISobs-SHIScalc) (K)

- AIRSobs (K)

- “Comparison 2” (21 November 2002) Excluding channels strongly affected by atmosphere above Proteus

## Summary

**Summary**

- The calibration uncertainty of advanced high spectral resolution observations are approaching the 0.1 K desired for climate applications
- Aircraft high spectral resolution observations from Scanning-HIS [& its cousin the NPOESS Airborne Sounder Testbed (NAST)] are now proven tools for the detailed validation of satellite based observations
-  AIRS is providing high quality global radiances for atmospheric sounding and climate applications

## Status of ARM Best EstimateT & Water Vapor Profiles:  Dave Tobin

-   288 overpasses to date
-   comparisons to T & water vapor retrievals    included after 16 Nov 2002
-   files and auxillary images online at     http://glacier.ssec.wisc.edu/~davet/     armBestEstimateFiles/sgp/v1.1/files.htm
-   NetCDF files also at     weather.jpl.nasa.gov/ in /home/davet/
-   Mean & Standard Deviation superior     to Global Radiosondes and ECMWF

**Status of ARM Best Estimate****T & Water Vapor Profiles:  Dave Tobin**

## ARM Best EstimateClear Case

- Red = Best EstimateBlue = Sonde1Green = Sonde2Magenta = AIRSBlack = AMSU

**ARM Best Estimate****Clear Case**

- Radiance Spectra

## ARM Best Estimate:  8 January 2003 Clear Case

**ARM Best Estimate:  8 January 2003 Clear Case**

## Red = Best EstimateBlue = Sonde1Green = Sonde2Magenta = AIRSBlack = AMSU

- Red = Best EstimateBlue = Sonde1Green = Sonde2Magenta = AIRSBlack = AMSU

**ARM Best Estimate****Cloudy Case**

- Radiance Spectra

## AIRS Observed-Calculated (UMBC): Clear, Night

**AIRS Observed-Calculated (UMBC): Clear, Night**

**Global****Radiosondes**

**ARM Best****Estimate**

## AIRS Observed-Calculated (UMBC): Clear, Night

**Global****ECMWF**

**ARM Best****Estimate**

## The following 3 slides show comparisons of the uncorrected and corrected profiles.  

- The first 2 slides are the RS-80s, which include all 3 corrections (rs80 time lag, contamination bias, temperature dependence calibration bias) for two representations of the contamination correction (“allage” and “maxage”)
- The third slide is for the RS-90s, which are corrected only for rs90 time lag.

**Comparisons of Corrected and Uncorrected**
**Vaisala RS-80 and RS-90 Radiosonde Profiles**
**from WVIOP2000**
- Corrections provided by Larry Miloshevich.

## Corrected for time lag, contamination (all-age) & T-dependent calibration

**Corrected for ****time lag, contamination (all-age) & T-dependent calibration**

## Corrected for time lag, contamination (maxage) & T-dependent calibration

**Corrected for ****time lag, contamination (maxage) & T-dependent calibration**

## Time-lag correction only

**Time-lag correction only**

## Notes:

- RS-80 corrections are large, resulting in wetter profiles, by up to ~50% wetter at 15km, much larger above 20km.
- RS-80 corrections significant even at the ground, due to the contamination contribution.
- RS-90 corrections are less than 5% up to 15km.
- RS-90 corrections result in *dryer* profiles, by up to 15% at 18km.
- The following slide shows the effect of the RS-90 corrections on AIRS calculated brightness temperatures.  This is a nadir case with the mean WVIOP2000 RS-90 profile, with and without the mean RS-90 correction.

## Slide 52