CAVIAR Field Campaign Mee ting, Imperial College 29 /3/11 TAFTS: Water Vapour Continuum Data from the 2008 CAVIAR Field Campaign Ralph Beeby, Paul Green, Juliet Pickering
Mar 28, 2015
CAVIAR Field Campaign Meeting, Imperial College 29/3/11
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
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
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
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
TAFTS Spectrum
• Run 4: 34,000ft (251mb), upwelling radiances
CAVIAR Field Campaign Meeting, Imperial College 29/3/11
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
Continuum
• Changes to continuum suggested by differences between TAFTS and LBLRTM
CAVIAR Field Campaign Meeting, Imperial College 29/3/11
Continuum (2)
• Some windows suggest correction of >100%
CAVIAR Field Campaign Meeting, Imperial College 29/3/11
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
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
Fine-tuning
• TAFTS?• Deghosting routine• Finish uncertainty analysis: , T 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
TAFTS/ARIES Inter-comparison
CAVIAR Field Campaign Meeting, Imperial College 29/3/11
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