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Satellite Cloud and Aerosol climate records for the ESA Climate Change Initiative (CCI) Caroline Poulsen, Gareth Thomas, Richard Siddans, Don Grainger, Adam Povey and Greg McGarragh RAL and University of Oxford and thanks also to CCI teams. Outline. Science

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  1. Satellite Cloud and Aerosol climate records for the ESA Climate Change Initiative (CCI)Caroline Poulsen, Gareth Thomas, Richard Siddans, Don Grainger, Adam Povey and Greg McGarraghRAL and University of Oxfordand thanks also to CCI teams.

  2. Outline • Science • Ingredients for a cloud and aerosol climatology • Instruments • Calibration • Algorithm • Aerosol/Cloud consistency • Future

  3. Clouds responses to greenhouse warming ftp://ftp-cmsaf.dwd.de/CCI/FeedbackLoop1/L3C/ Image from IPCC report We need long term observational records to verify and quantitatively assess

  4. Instruments (which will be processed using ORAC algorithm) • Visible/IR • AVHRR 1982-2012 (Cloud) • A/ATSR (1991)1995-2010 (Cloud and Aerosol) • MODIS 2000-2014 (Cloud) • Approx 300 TB output products. • 3,600,000 CPU processing hours

  5. Calibration and Stability ATSR stability, slides courtesy Dave Smith RAL

  6. ORAC (Oxford RAL Aerosol and Clouds) 62% of points agree with Cloudsat within the average uncertainty estimate(For an ideal error budget, it should be 66%) True uncertainty= Cloudsat-AATSR • Optimal estimation algorithm • http://proj.badc.rl.ac.uk/orac • Pixel level uncertainty • Visible and IR channels used together to ensure: • Radiative consistency • All surface-atmosphere properties determined from a satellite instrument are consistent with the TOA radiance field. Forward model systematic

  7. Less low clouds • More clouds at the poles • Poleward shift in clouds • Rising of the melting layer • Rising level of high cloud • Less low clouds? • More clouds at the poles? • Poleward shift in clouds? • Rising of the melting layer? • Rising level of high cloud? • ?? Example AATSR cloud products

  8. Aerosol effects on clouds

  9. Consistency: The global TOA radiation field is generated from a mixture of clear and cloudy skies. • Aerosol and Cloud retrieved using similar algorithm • Aerosol and Cloud will use a consistent cloud identification

  10. Comparison of aerosol CCI and cloud CCI cloud masks AEROSOL CCI/ CLOUD CCI • Aerosol CCI applies a tight cloud flagging criteria. • Cloud CCI misidentifies some thick aerosol as cloud • Many observations are considered neither clear nor cloudy so that the global TOA radiance field simulated from the two products is not representative of the satellite measured field.

  11. Cloud and Aerosol CCI identification consistencyCloud and Aerosol retrievals over polluted China Aerosol_cci L2 (ORAC) aerosol optical depth AATSR false colour Cloud_cci L2 (CC4CL/ORAC) cloud optical depth Bayesian Identification White: aerosol Blue/Purple:ice/water

  12. Summary • Algorithm development • Focusing on radiative consistency and minimising the differences between cloud and aerosol CCI products • Uncertainty definitions and representation and validation. • See Adam Povey’s poster in this session • We are preparing to process a lot of data • Evaluation and science analysis

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