# Presentation: 258118

## Spectroscopic Issues Associated with Atmospheric Remote Sensing

**Tony Clough,  Mark Shephard and Jennifer Delamere **
**Atmospheric & Environmental Research, Inc.**
**Colleagues**
**University of Wisconsin**
**International Radiation Symposium**
**Busan, Korea**
**August 2004**

**Spectroscopic Issues Associated with ****Atmospheric Remote Sensing**

## Evaluation of CCM3 with HIRS Radiances

- Iacono et al., JGR 2003
- Cloud Cleared:	  Bates
- Channel 4:  	Temperature Field
- Channel 12:  	Water Vapor Field

## Slide 3

## Slide 4

## Remote Sensing of Ozone

- Ozone Sonde Issues  (Spatial, Temporal, Accuracy)
-  extremely valuable
- Ozone Spectroscopy
-   Flaud - French Group: 0%
-   Maryanne Smith - Langley: +3%
-   UV:  **-**5%
-   Microwave: Pure Rotation Lines

## Remote Sensing of Water Vapor at the ARM Sites

- 	Sonde Issues  (Spatial, Temporal, Accuracy (Bias))
- Column:  Microwave
- Atmospheric Measurement (mwr scaled sondes)
- Transition Frequencies
- Strengths  (Stark Effect: 0.5%)
- Widths (Temperature Dependence)
- Shape:     Voigt
- Continuum
- 	Tropospheric Profile:  Raman Lidar
- Night/Day
- Cloud Clearing

## Spectral Brightness Temperature and MWR Frequencies

## MWRP / MonoRTM Residuals   (5 frequencies)

**    ****	****	****	****HalfWidth: ****MONORTM Value**
**    ****	****	****PWV:   ****Retrieved from 23.835 GHz  BT_MWRP**** **
**a**** + ****b**** * BT_MWRP**

## MWR - Modeled (PWV scaled to match 23.8 GHZ MWR)

## Slide 10

## Slide 11

## Remote Sensing of Temperature in the Infrared

- Carbon Dioxide
- Transition Frequencies   (Pressure Shift)
- Strengths
- Widths (Temperature Dependence)
- Shape:
- Voigt
- Chi Function   (function and temperature dependence)
- Galatry ....      (transition from Doppler to Voigt)
- Line Coupling (Perturbation Approach/Exact Diagonalization)
- Q Branches
- P and R Branches
- Continuum

## Slide 13

## Slide 15

## Slide 16

## Slide 17

## AIRS Validation with Retrieved Temperature Profile

- AIRS Validation with Retrieved Temperature Profile

- AIRS
-       1200 resolving power
- LBLRTM HITRAN 2000
- LBLRTM (Gaussian)

- CO2  (2)        O3               CH4           H2O  (1.63 prec. cm pwv)                         CO2 (3)

## Slide 19

## Slide 20

## Remote Sensing of Water Vapor in the Infrared

- Atmospheric Measurement (mwr scaled sondes)
- Transition Frequencies   (Pressure Shifts)
- Strengths
- Widths (Temperature Dependence)
- Shape:     Voigt
- Continuum

- Definition:  Continuum is that absorption with slow spectral dependence which,
- 	 when added to the line by line absorption, provides agreement with measurement.
- Scaling:	 Dependence on pressure, temperature and mixing ratio must be ‘robust’
- mt_ckd:	Contributions from two sources:
- Allowed line contribution
- Collision-Induced contribution

## Slide 22

## Slide 23

## Slide 24

## Slide 25

## Summary

- Water Vapor
- Effectively no ground truth
- Reasonable consistency across the band
- NO evidence (yet) for
- line shape other than Voigt
- higher spectral content for the continuum

- Significant improvement in line parameters since IRS 2004 (MIPAS-EOS)  **BUT**
- Spectroscopy is the current limitation on the accuracy of retrievals from space!

- Carbon Dioxide
****2 and ****3 are not consistent   (****2 strengths are effectively  ~4%  .gt.  ****3)
- Water vapor temperature retrieval consistent with ****3
- Issues
- chi factor
- Continuum
- Line coupling:  Q and P & R

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