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TAFTS: Water Vapour Continuum Data from the 2008 CAVIAR Field Campaign

TAFTS: Water Vapour Continuum Data from the 2008 CAVIAR Field Campaign. Ralph Beeby, Paul Green, Juliet Pickering. Outline. Introduction LBLRTM simulations TAFTS flight data LBLRTM/TAFTS comparison: Flight B400 Continuum coefficients Conclusions & further work. Introduction.

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TAFTS: Water Vapour Continuum Data from the 2008 CAVIAR Field Campaign

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  1. TAFTS: Water Vapour Continuum Data from the 2008 CAVIAR Field Campaign Ralph Beeby, Paul Green, Juliet Pickering CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  2. Outline • Introduction • LBLRTM simulations • TAFTS flight data • LBLRTM/TAFTS comparison: Flight B400 • Continuum coefficients • Conclusions & further work CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  3. Introduction • TAFTS mounted on-board UKMO/FAAM BAe-146 for CAVIAR field campaigns • Aim: to use TAFTS spectra to measure the water vapour continuum in the far-IR • Method: • LBLRTM uses current model of water vapour continuum to simulate atmospheric spectra • Compare TAFTS (observed) spectra with LBLRTM (simulated) spectra • Differences between TAFTS and LBLRTM  changes to continuum? • Case study: flight B400, 18/09/2008, Camborne CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  4. Simulating Spectra with LBLRTM • LBLRTM takes 1-D atmospheric profile as input – need to estimate temperature and water vapour profiles from sondes and aircraft data • Uses MT_CKD 2.5 continuum – can adjust the strength within the simulation for comparison with TAFTS data • Below: spectrum for run 4 (34kft / 251mb) UW CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  5. TAFTS Spectrum • Run 4: 34,000ft (251mb), upwelling radiances CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  6. TAFTS Spectrum: Windows • Spectral features of continuum visible in windows between strong WV absorption lines • Compare TAFTS and LBLRTM in windows to see where continuum needs adjustment CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  7. Continuum • Changes to continuum suggested by differences between TAFTS and LBLRTM CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  8. Continuum (2) • Some windows suggest correction of >100% CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  9. Continuum (3) • Currently large uncertainties associated with data • Size of spread mostly due to differences between TAFTS and simulation CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  10. Comparison • Still parts of windows where TAFTS and LBLRTM do not agree • Option 1: adjust TAFTS data • Option 2: adjust simulations CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  11. Fine-tuning • TAFTS? • Deghosting routine • Finish uncertainty analysis: e, DT error • LBLRTM? • Differences between LBLRTM and observed spectra can suggest where T or WV profile need adjusting • 1DVar retrieval scheme performed using ARIES data (Courtesy S Newman) - see how this affects far-IR CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  12. TAFTS/ARIES Inter-comparison CAVIAR Field Campaign Meeting, Imperial College 29/3/11

  13. Conclusions & further work • First corrections to continuum from B400 – hope to refine these values • Improve TAFTS data with de-ghosting routine, improve simulation with adjustments to profile – retrieval • Repeat for other runs – are they consistent? • Compare continuum with ARIES data CAVIAR Field Campaign Meeting, Imperial College 29/3/11

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