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Alain Protat, Julien Delanoë, LATMOS John Haynes, Colorado State University

Southern Ocean Clouds and Meteorology Workshop, 27 November 2012. Southern Ocean Clouds Characterization using CloudSat, CALIPSO, and the ISCCP regimes. Alain Protat, Julien Delanoë, LATMOS John Haynes, Colorado State University Christian Jakob , Monash University.

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Alain Protat, Julien Delanoë, LATMOS John Haynes, Colorado State University

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  1. Southern Ocean Clouds and Meteorology Workshop, 27 November 2012 Southern Ocean Clouds Characterization using CloudSat, CALIPSO, and the ISCCP regimes Alain Protat, Julien Delanoë, LATMOS John Haynes, Colorado State University Christian Jakob , Monash University

  2. The Southern Ocean Clouds Problem Courtesy of J. Haynes

  3. The Southern Ocean Clouds Problem Courtesy of J. Haynes Hypothesis : Not enough low-level clouds in models

  4. Southern Ocean Cloud Frequency of Occurrence CloudSat-CALIPSO CFO (Mace et al. 2009) 70% of low-level clouds (underestimated) 90-95% ! 10% of mid-level clouds 20% of high clouds

  5. Questions 1 – Why do models fail to reproduce the radiation budget in the SHB ? Is it cloud occurrence ? Statistical Overlap assumption in models in this area ? Details in the microphysical properties of low and high clouds ? 2 – Significant amounts of supercooled liquid water have been inferred from past aircraft measurements in the area. Could it explain why models behave badly in the SHB ? 3 – There is a seasonal dependence of model skills (DJF is the worst period). Why is that ? Any change in the microphysical properties ? More generally, is model skill dependent on “cloud regime” in the SHB ? The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology

  6. The cloud regimes in the SHB Haynes et al. (JCLIM 2010) : 8 cloud regimes have been identified (ISCCP histograms) S1,S2 : low-topped clouds S3,S4,S5 : middle-topped clouds S6 : high-topped clouds, moderate OT S7 : midlatitude precip systems S8 : cirrus North part of SHB : S1, S2 South part of SHB : S4, S5 The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology

  7. Thermodynamic phase : CloudSat-CALIPSO Delanoë and Hogan (2010, JGR) : DARDAR Temperature model (ECMWF) => Ice / Liquid water Simple method : Different response of radar and lidar in presence of supercooled liquid water: Very strong lidar extinction where there is no specific radar signal Courtesy of J. Delanoë, LATMOS The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology

  8. Colocating ISCCP regimes / DARDAR Mask Period available (DARDAR+ISCCP regimes) : 200606 to 200806 (2 years) Time resolution : 3 h The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology

  9. Cloud Phase versus Cloud Regime 70% of ice, up to 80-90% for S6, S7, S8 Large variability among regimes More slw and ice+slw in regimes S3, S4, S5 Up to 10-15% of rain in most regimes The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology

  10. Ice microphysics versus Cloud Regime Probability distribution functions (PDFs) Z b b Z IWC a IWC a Re N0* N0* Re S1 : 13 % (37) S2 : 3 % (8) S3 : 2 % (10) S4 : 11 % (10) S5 : 16 % (12) S6 : 22 % (10) S7 : 30 % (10) S8 : 2 % (4) CloudSat is not sensitive enough to detect all SHB clouds (probably S1 low-level clouds) Regime dependence of statistical microphysical properties is generally large Modal value of effective radius is very variable from one regime to the next. The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology

  11. Ice microphysics versus Cloud Regime Mean Vertical Profiles Z b b Z IWC a IWC a Re N0* N0* Re Regime dependence of the mean vertical profile of all microphysical properties is large The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology

  12. Next steps Regime dependence of low-level cloud microphysical properties (which retrieval method ?) Seasonal and spatial distributions of the regime dependence of cloud microphysics Evaluate if the ACCESS model parameterizations reproduce this observed variability as a function of season, spatial distribution, and cloud regime The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology

  13. Thank you Alain Protat Southern Ocean Clouds Characterization using CloudSat, CALIPSO, and the ISCCP regimes Email: a.protat@bom.gov.au Thank you

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