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CCI Cloud Assessment. Mark Ringer, Met Office Hadley Centre CMUG 4 th Integration meeting, Exeter – June 2 nd – 4 th , 2014. Introduction. CCI clouds produces a range of cloud parameters: cloud amount, cloud liquid water, cloud effective radius, etc
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CCI Cloud Assessment Mark Ringer, Met Office Hadley Centre CMUG 4th Integration meeting, Exeter – June 2nd – 4th, 2014
Introduction • CCI clouds produces a range of cloud parameters: cloud amount, cloud liquid water, cloud effective radius, etc • Includes merged (all sensors) and individual sensor products (AATSR, MODIS, AVHRR) • Phase 1 prototype data set covers 2007 – 2009 • Product definitions correspond to GEWEX cloud assessment – not specifically model-oriented • We previously used ISCCP as a precursor data set
General comments – comparison with other cloud data sets • Cloud amount underestimated over global oceans • High-level cloud underestimated over land in tropics and mid-latitudes • Low-level cloud underestimated over sub-tropical oceanic stratocumulus areas (e.g. California, Peru) • Large underestimate of thin cirrus cloud (algorithm? channel selection?)
Cloud liquid water HadGEM2 vs. obs: JJA 2007
Cloud droplet effective radius CCI merged product: JJA 2007 OBS MODEL – OBS
Cloud droplet effective radius CCI individual sensor products OBS MODEL – OBS
Comments • Interpretation of model simulation depends on data set being used for comparison • We need to understand how/why CCI differs from other data sets of comparable cloud parameters • Why is LWP closer to SSM/I? • Why is CCI MODIS/ATSR different from standard MODIS/ATSR products? • Interpretation of merged products?
Phase 2 – modelling perspective • A long-term record suitable for identifying trends in cloud would be of great interest…but there are risks • Could also focus on interannual variability & model evaluation/development to show value of CCI • Consider relation to large amount of current & future work in this area, e.g. CFMIP, WCRP grand challenge on clouds, circulation & climate sensitivity • Specific model-oriented products may be required • Merged products unlikely to be of use to modellers – emphasis on forward-modelling individual sensors (COSP)
Interannual variability 1997-98 ENSO: Models vs. ISCCP