CAVIAR – Continuum Absorption by Visible and Infrared Radiation and its Atmospheric Relevance PI: Keith Shine Department of Meteorology, University of Reading Co-I’s: Stephen Ball Department of Chemistry, University of Leicester Tom Gardiner National Physical Laboratory Roderic Jones Department of Chemistry, University of Cambridge John Harries, Juliet Pickering Blackett Laboratory, Imperial College London Kevin Smith Rutherford Appleton Laboratory, STFC Jonathan Taylor and Stuart Newman Met Office Jonathan Tennyson Department of Physics, University College London Co-ordinator: Igor Ptashnik Dept of Meteorology, Univ of Reading And (roughly!) 5 post-doc researchers and 3 PhD
Transcript
CAVIAR – Continuum Absorption by Visible and Infrared Radiation and its Atmospheric
RelevancePI: Keith Shine Department of Meteorology, University of Reading Co-I’s: Stephen Ball Department of Chemistry, University of LeicesterTom Gardiner National Physical LaboratoryRoderic Jones Department of Chemistry, University of Cambridge John Harries, Juliet Pickering Blackett Laboratory, Imperial College LondonKevin Smith Rutherford Appleton Laboratory, STFCJonathan Taylor and Stuart Newman Met OfficeJonathan Tennyson Department of Physics, University College LondonCo-ordinator: Igor Ptashnik Dept of Meteorology, Univ of ReadingAnd (roughly!) 5 post-doc researchers and 3 PhD students
We know …
• Water vapour is by far the most important greenhouse gas in the atmosphere; we know it is important for remote sensing; we know it is an important contributor to climate feedbacks We also know
…
• That it possesses a radiatively-important continuum, pervasive from the visible to microwave, which is represented in many models in a semi-empirical way, using observations from a limited number of wavenumbers and measurement conditions
Major Aims • Describe the continuum across a broad wavelength range and a broad range of atmospheric and near-atmospheric conditions, using both laboratory and field measurements
• Explain the underlying cause of the continuum – can we separate out far-wing line shape contributions from dimer explanations?
• Provide the community with an improved continuum model (perhaps in a CKD-like form)
visible near IR mid IR far IR
Measurements
WP1 Molecular Modelling
WP2 Laboratory Measurements
WP3 Field Measurements
WP4 Synthesis Everyone!
WP5 Impact on Understanding
WP6 Provision of model for wider use
Everyone!
The Programme
The work flow
line-by-line radiative transfer models
existing continuum models
existing spectral line databases
targeted lab measurements
field campaigns
Instrument upgrades and calibration
dimer model development
dimer model refinement
new continuum model
impact on understanding of atmospheric processes, incl climate and remote sensing
preparation of continuum model for community use
synthesisrefinement of line database
Work commenced …
Work soon commencing! …
The Project• Formally, we started on 1 October 2006 … will formally end 30 June 2011 (including a no-cost extension)
• Annual meetings with international involvement
Major progress in second year: 1
• Development of a new potential energy surface for water dimer, which will allow improved ab-initio calculations of its spectra
• Analyses of new laboratory measurements to derive the continuum across the near-infrared
Major progress in second year: 2
• Advances in the broadband cavity-ringdown and cavity-enhanced methodologies and new results
• A major calibration exercise so that all CAVIAR field instrumentation are now traceable to the same standard
Major progress in second year: 3
• A major field campaign using aircraft and ground-based high-spectral resolution spectrometers, plus supporting data
Photo from Liam Tallis
Challenges for third year: 1
• Production of new ab initio dimer spectrum and comparison with measurements
• New laboratory measurements using both “traditional FTS” and “cavity” – a particular emphasis will need to be on the between-band absorption, as this is most important for the “AR” in “CAVIAR”
Challenges for third year: 2
• Analysis of new laboratory measurements
• Full analysis of calibration of field instruments
• Full analysis of Camborne Field Campaign
• The second field campaign at Jungfraujoch in summer 2009
Challenges for third year: 3
Begin serious work on the three remaining workpackages:
• Synthesis of lab and field measurements and theoretical work
• Modelling the impact of the continuum on the radiation balance
• Developing a continuum model for community use
Clough et al. J.Geophys.Res, 1992
Conclusions• In Year 2, we have made significant progress in
model and instrument development, acquired and analysed new laboratory data, performed the major Camborne field experiment, and have advanced plans for the Jungfraujoch 2009 campaign
• The legacy of the project: - extensive new set of observations over a wide
range of conditions in both lab and field - new physically-based continuum model with wide
range of potential users – in basic science, in weather and climate prediction and in remote sensing
- cohort of post-docs and students trained in a cross-disciplinary environment
