1. clouds assessments GEWEX Stubenrauch CREW Roebling

2. GEWEX, global & level 3 available level 3 monthly cloud products –global, 1x1 degree lat/lon data –multi-annual temporal coverage –netcdf / CF convention inter-compare & document & evaluate –cloud cover … stratified by altitude –cover in the context of other cloud products (opt. depth, cloud  -physics and cloud water) provide recommendation on data-use

3. CREW - local, level 2 CREW (Cloud Retrieval Evaluation Workshops) analysis for selected ‘golden days’ complementary to GEWEX assessment, by offering explanations for discrepancies –explore retrieval issues ( e.g. cloud detection) –explore averaging issues ( e.g. level 2  level 3) provide insights on links to other atmospheric properties (also with geo-stationary data) –support process underst. in climate modeling

4. clouds much more than cloud cover … so that associated impacts on the atmospheric radiative fluxes can be determined and compared Variable Horizontal Res Vertical Res Temporal Res Accuracy Stability (/decade) CA50kmN/A3hr0.01 – 0.050.003 – 0.03 CP50kmNA3hr15hPa – 50hPa3hPa -15hPa CT50kmNA3hr1K – 5K0.2K – 1K CWP50kmNA3hr25%5% CRE50kmNA3hr 5-10%1-2% cloud cover cloud top press cloud top temp water path effective radius optical depth

5. participating data-sets all properties, mature ISCCP ISCCP 1984-2007 (Rossow et al.) TOVS Path-B TOVS Path-B 1987-1994 (Stubenrauch et al.) AIRS-LMD AIRS-LMD 2003-2009 (Stubenrauch et al.) MODIS- S T eam MODIS-CERES MODIS- S cience T eam 2001/3-2009 (Ackerman / Platnick et al.) MODIS-CERES 2001/3-2006 (Minnis et al.) all prop, less mature PATMOS-x PATMOS-x (AVHRR)1982-2009 (Heidinger et al.) ATSR-GRAPE ATSR-GRAPE 1999/03-09 (Poulsen et al.) only cover & top-p/T HIRS-NOAA HIRS-NOAA 1982-2008(Wylie et al., Menzel et al.) CALIPSO- ST eam CALIPSO- S cience T eam 2007-2008 (Winker et al.) CALIPSO-GOCCP CALIPSO-GOCCP 2007-2008 (Chepfer et al.) CLOUDSAT-geoprof 2007-2009 (Mace et al.) complementary MISR MISR 2001-2007 (DiGirolamo et al.) POLDER POLDER (O2 & Rayl.) 2006-2008 (Riedi et al.)

6. what have we learned ? (1) centralization (person and web-location) –a committed (and respected) leader –a central data-depot –a standard input (global modeling ‘likes’ netcdf / CF) regular meetings keep momentum –focus on getting issues solved & reprocessing request –develop personal friendships by common interests establish working groups –conduct experiments on common sub-topics –relieve pressure on ‘leader’ (incl. publications)

7. what have we learned ? (2) delays without support for leadership … thus $$$ support for central setup (more $$ at beginning) –web/site & collection & portal setup / maintenance –help on individual data preparation –tools for data comparisons –preparation / $$$ for regular meeting –regular newsletters –Preparation of reference data $$ support for subtask organization $$ support for bringing experts to once user community sees value there will be additional $