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CO2 Spectroscopy Evaluation

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Page 19th Biennial HITRAN Database Conference9th Biennial HITRAN Database ConferenceCOCO22 Spectroscopy Evaluation Using Spectroscopy Evaluation UsingAtmospheric Solar Absorption SpectraAtmospheric Solar Absorption SpectraBhaswar Sen, Linda R. Brown, Charles. E. Miller,Geoffrey C. Toon and Robert A. TothJet Propulsion LaboratoryCalifornia Institute of TechnologyPasadena, CaliforniaRebecca A. Washenfelder and Paul O. WennbergCalifornia Institute of TechnologyPasadena, California2 of 209th Biennial HITRAN Database Conference June 22, 06The broad spectral coverage of FTS solar absorption spectra, together withtheir high SNR and resolving power, make them very useful for assessing theadequacy of the CO2 spectroscopic databases. Unambiguous photon path history• All measured photons come from the Sun. Achieve large optical densities• Path lengths of up to 100 km Evaluate significant omissions in the current linelist• Missing gases, isotopologues, hot bands. Evaluate pressure-dependent parameters• Widths, shifts, collision-induced absorption Evaluate adequacy of physics• Far-wing line shapes, line-mixing. Assess consistency of spectral parameters between different regions• Broad spectral coverageWhy Use Solar Absorption Spectra?3 of 209th Biennial HITRAN Database Conference June 22, 06Mass: 250 kg, Size: 1.4 x 0.7 x 0.8 m.Parallel HgCdTe & InSb detectorssimultaneously cover 650-5650 cm-1.KBr beamsplitter & compensator.Double-passed configuration up to120 cm OPD (0.008 cm-1 resolution).The JPL MkIV Balloon-Borne Interferometer4 of 209th Biennial HITRAN Database Conference June 22, 06Park Falls Automated Solar Observatory447-m WLEF tower← In situ and Ground-based FTIR ↓5 of 209th Biennial HITRAN Database Conference June 22, 06Size: 3 x 2 x 1 m.Parallel Si Diode & InGaAs detectorssimultaneously cover 3900-15600 cm-1.CaF2 beamsplitter & compensator.Double-passed configuration up to 159cm OPD (0.0062 cm-1 resolution.)HCl cell for wavelength and ILScalibrationThe IFS 125HR InterferometerScannerInterferometerDetectorsSolar Beam6 of 209th Biennial HITRAN Database Conference June 22, 06Relative Advantages of Solar Absorption Spectra:Balloon-Borne versus Ground-BasedMkIV balloon-borne solar occultation spectra Evaluate line positions Evaluate relative band strengths Small line-of-sight H2O column Solar and instrumental features are removed by ratioing with low-airmass spectrumIFS 125HR ground-based solar absorption spectra Evaluate air-broadened widths and pressure-induces shifts Absolute band strengths• Continuous Psurf measurements by CIT (0.1 hPa precision)• In situ CO2 profile (0.1 ppmv precision)• Continuous profiles by NOAA (0 - 400 m)• Weekly air-borne profile by NOAA (<4 km)• Periodic air-borne profile by Harvard University (<12 km)• Radiosonde temperature profile (1 K <30 km)7 of 209th Biennial HITRAN Database Conference June 22, 06The JPL 2006 CO2 Interim Linelist* Based on new analysis of 42 CO2 laboratory spectra recorded with theKitt Peak FTS at 0.01 cm-1 resolution.• Cell lengths of 3.47 cm, 2.46 m and 25 - 410 m•12C16O2 with normal (0.9842) and enhanced (0.9952) abundance• Assumes Voigt line shapes• Band strength uncertainties < 0.5% (J′ ≤ 40)• 58 new band strengths measured for the main isotope• Self-broadened widths and pressure-induced shifts for 15 bands Improved 12C16O2 molecular line parameters: 4500 - 6989 cm-1• 4188 transitions for 8 isotopologues (Smin = 4.x10-28)• HITRAN 2004 spectral parameters for other isotopes• Air-broadened widths similar to HITRAN 2004• Air-broadened shifts estimated from near-infrared N2O (HITRAN 2004 has shifts equal zero in this spectral range)*C.E. Miller: Line mixing in pure CO2 at 6348 cm-1*R.A. Toth: Line strengths and self-broadening coefficients of CO2 from 4600 - 7000 cm-18 of 209th Biennial HITRAN Database Conference June 22, 06The high-resolution MkIV balloonspectrum allows us to investigateerrors in the line positions.In this and all following figures,diamond symbols represent measuredspectrum. Line represents fittedcalculation.The upper panel illustrates 3 wrongCO2 line positions in HITRAN 2004.The lower panel illustrates fits to thesame spectrum using the improvedJPL 2006 CO2 spectroscopy.The error in the CO2 line positions isresolved.Spectroscopy of CO2: Line Position Error9 of 209th Biennial HITRAN Database Conference June 22, 06The high-resolution MkIV balloonspectrum allows us to investigatemissing lines.The upper panel illustrates a weakmissing CO2 transition in HITRAN2004.The lower panel illustrates fits to thesame spectrum using the JPL 2006CO2 spectroscopy.Spectroscopy of CO2: Missing Lines10 of 209th Biennial HITRAN Database Conference June 22, 06Fits to MkIV spectrum (31 km tangentaltitude) with HITRAN 2004 (upperpanel) and JPL 2006 (lower panel)CO2spectroscopy, respectively.The σrms has improved nearly 70%.Note the low amount of H2O absorptionin the limb spectrum.The 20013←00001 band is used byMkIV to determine observationgeometry.It will also be used by OCO to measureatmospheric CO2.Spectroscopy of CO2: The 2 µm Fermi Triad11 of 209th Biennial HITRAN Database Conference June 22, 06Fits to the IFS 125HR ground-basedsolar absorption spectrum with HITRAN2004 (upper panel) and JPL 2006(lower panel) CO2 spectroscopy,respectively.The σrms has improved nearly 50%.Note the significant H2O absorption inthe ground-based spectrum.Spectroscopy of CO2: The 2 µm Fermi Triad12 of 209th Biennial HITRAN Database Conference June 22, 06Fits to the IFS 125HR ground-basedsolar absorption spectrum with HITRAN2004 (upper panel) and JPL 2006 (lowerpanel) CO2 spectroscopy, respectively.The σrms has improved nearly 40%.The 1.6 µm (30013←00001) band willalso be used by OCO to measureatmospheric CO2.Spectroscopy of CO2: The 1.6 µm Fermi Tetrad13 of 209th Biennial HITRAN Database Conference June 22, 06Spectroscopy of CO2: The 1.58 µm Fermi TetradFits to the IFS 125HR ground-basedsolar absorption spectrum with HITRAN2004 (upper panel) and JPL 2006 (lowerpanel) CO2 spectroscopy, respectively.The σrms has improved nearly 30%.The 1.58 µm (30012←00001) band isused by SCIAMACHY to measureatmospheric CO2.14 of 209th Biennial HITRAN Database Conference June 22, 06Fits to the IFS 125HR ground-basedsolar absorption spectrum withHITRAN 2004 (upper panel) and JPL2006 (lower panel).Using HITRAN 2004, the 1.65 µm(30014←00001)


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