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Tony Clough, Mark Shephard and Jennifer Delamere Atmospheric & Environmental Research, Inc.

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.

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Tony Clough, Mark Shephard and Jennifer Delamere Atmospheric & Environmental Research, Inc.

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  1. 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

  2. Evaluation of CCM3 with HIRS Radiances • Iacono et al., JGR 2003 • Cloud Cleared: Bates • Channel 4: Temperature Field • Channel 12: Water Vapor Field

  3. 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

  4. 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

  5. Spectral Brightness Temperature and MWR Frequencies

  6. MWRP / MonoRTM Residuals (5 frequencies) HalfWidth: MONORTM Value PWV: Retrieved from 23.835 GHz BT_MWRP a + b * BT_MWRP

  7. MWR - Modeled (PWV scaled to match 23.8 GHZ MWR)

  8. Atmospheric Validation of Forward Model • Measurement • Instrument Function - Photometry • AERI - HIS AIRS sfc air space • Characterization of the Atmospheric Path including Surface • Sonde • Temperature • Water Vapor • Forward Model • Line Parameters • LBLRTM (line shape) • Continuum Atmospheric Spectroscopy from Space: long paths, cold temperatures

  9. “AIRS SHIS Comparison 2” (21 November 2002) Excluding channels strongly affected by atmosphere above ER2 Revercomb et al. (AIRSobs-AIRScalc)- (SHISobs-SHIScalc) (K)

  10. 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

  11. Continuum: Includes following contributions • 25 cm-1 beyond line center • within -/+ 25 cm-1 at 25 cm-1 value Chi function: The spectral function by which the Lorentz line shape (impact) must be multiplied to obtain the “true” line shape.

  12. AERIDownwelling at the Surface Arctic SHIS AFWEXUpwelling at 8 km Dry

  13. AIRS Validation with Sonde/Climatological Profile • AIRS 1200 resolving power • LBLRTM HITRAN 2000 • LBLRTM (Gaussian) CO2 (n2) O3 CH4 H2O (1.63 prec. cm pwv)CO2 (n3) HITRAN 2000 H2O Stratosphere Troposphere

  14. Residuals vs Brightness Temperature n2 band n3 band Stratosphere Troposphere

  15. Temperature Retrieval using the n3 CO2 Band Climatology Sonde

  16. H2O AIRS Validation with Retrieved Temperature Profile • AIRS 1200 resolving power • LBLRTM HITRAN 2000 • LBLRTM (Gaussian) CO2 (n2) O3 CH4 H2O (1.63 prec. cm pwv)CO2 (n3)

  17. AIRS 1200 resolving power • LBLRTM HITRAN 2000 • LBLRTM (Gaussian) • AIRS 1200 resolving power • LBLRTM HITRAN 2000 • LBLRTM (Gaussian) CO2 (n2) O3 CH4 H2O (1.63 prec. cm pwv)CO2 (n3) CO2 (n2) O3 CH4 H2O (1.63 prec. cm pwv)CO2 (n3) HITRAN 2000 AIRS Validation with Sonde/Climatological Profile H2O AIRS Validation with Retrieved Temperature Profile (n3)

  18. n2

  19. 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

  20. AERI_ER Validation in the Polar Window ARM NSA Retrieved Column Water Vapor HITRAN 2000/2004 mt_ckd_1.1 Radiance(mW / m^2 sr cm-1) N2O Q Branch CO2 Q Branch Wavenumber (cm-1)

  21. AERI Downwelling at the Surface ARM SGP Moist Toth _1%

  22. CAMEX HISUpwelling at 20 km Ocean - low pwv Temp: R (n2) CO2 Water Vapor: Sonde Temp: R (n2) CO2 Water Vapor: Retrieved Temp: Retrieved Water Vapor: Retrieved

  23. HIS CO Region:Upwelling at 20 km Ocean low pwv __ __ __ __ __ H2O CO2 Q

  24. http://rtweb.aer.com • 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 • Carbon Dioxide • n2 and n3 are not consistent (n2 strengths are effectively ~4% .gt. n3) • Water vapor temperature retrieval consistent with n3 • Issues • chi factor • Continuum • Line coupling: Q and P & R Significant improvement in line parameters since IRS 2004 (MIPAS-EOS)BUT Spectroscopy is the current limitation on the accuracy of retrievals from space!

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