1. EUMETSAT, July 2013 Coordination Group for Meteorological Satellites - CGMS Cloud Retrieval Evaluation Working Group by EUMETSAT Presented to CGMS-41, WGII/8

2. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS Background

3. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS Introduction Contribution to CGMS-40 At CGMS-40 (CGMS-40 EUM-WP-10) the Cloud Retrieval Evaluation Working Group (CRE-WG) presented first ideas to establish a permanent International Clouds Working Group within CGMS. Action CGMS-40: WG II Action 40.26 To request the CRE-WG to develop a proposal related to establishment of a new International Science WG, involving all CGMS members and WMO, WCRP and GCOS, including the proposed focus of the group, an account of ongoing activities in other fora (a “gap analysis”), and financial implications, for discussion at CGMS-41.

4. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS Motivation Cloud parameter are increasingly used in data assimilation for Numerical Weather Prediction (NWP), regional now-casting especially for severe weather forecasting, cloud-chemistry modelling, and more; CGMS members do more and more include cloud detection and cloud parameter retrievals in their operational services; CGMS members ask for a mechanism that establishes links to the cloud parameter retrievals community and that facilitates: - access to, and sharing of, knowledge; - developments towards, and sharing of, commonality approaches, - a forum for the exchange of requirements, - a forum for training. The international Clouds Working Group within CGMS that is presented in this working paper aims to provide such a mechanism.

5. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS Response to CGMS-40: WG II Action 40.26

6. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS 1: Nomination of CREW representatives NameOrganisationCountry Mr. Chung, Sung-RaeNational Meteorological Satellite Center, KMAKorea Ms. Takeuchi, Ayako Meteorological Satellite Center (MSC) Japan Meteorological Agency (JMA)Japan Dr. Puviarasan, N.India Meteorological DepartmentIndia Dr. Rublev, AlexeiRoshydrometRussia Dr. Bojinski, StefanWMOSwitzerland Dr. Heidinger, AndrewNOAAUSA Dr. Roebeling, RobEUMETSATGermany Dr. Feng, LuCMAChina Table : Names of CGMS representatives for the International Cloud Working Group

7. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS 2: GAP Analysis Ongoing activities Other Cloud Working Groups: GEWEX-CA (completed, follow up not planned) Conferences: e.g. AMS, ISARD, IRS, EUMETSAT Scientific and Operational Projects: e.g. ISCCP, ESA-Clouds-CCI, CM SAF Gap analysis Currently no active working group; Conferences do not offer the required exchange platform; Projects do part of the work, coordination is needed.

8. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS 3: Focal points of CREW to exchange knowledge on parameter retrieval algorithms; to contribute to the assessment of level-2 cloud parameter retrievals; to contribute to the validation of level-2 cloud parameter retrievals; to foster commonality for operational cloud parameter retrievals among the different CGMS satellite operators; to support and stimulate training of the operational and scientific community; to enhance the communication in this field and develop international partnerships.

9. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS CREW activities

10. EUMETSAT, July 2013 Coordination Group for Meteorological Satellites - CGMS Inter-algorithm consistency: Cloud mask MSG 13 June 2008, 12 hr UTC Fig. : Cloud masks of 11 MSG algorithms (13 June 2008, 12 hr UTC)

11. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS Inter-algorithm consistency : Multiple Algorithm Ensemble analysis COT CTP in hPa Re in micron

12. EUMETSAT, July 2013 Coordination Group for Meteorological Satellites - CGMS Why Space-Time Grid data? Benefits Data reduction; Uniformity & Accessibility; Product statistics and error information; Multi-satellite time series analysis; Meaningful data assessments; Bridges the gap to the model community. Towards Uniformity and Traceability – Aggregation methods Hurdles Preserving level-2 statistics; Sensitivity to selection criteria; (angels, cloud mask, quality, etc) Sensitivity to number of observations; Mitigating sampling errors in space & time; Handling product specific rules; Need for coordination. (success depends on adoption of a generic approach) Aim To develop a generic, and high-quality, approach for producing long-term (global) climate data records at level-3 that can be used for studying trends on seasonal, inter-annual and decadal time scales.

13. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS Level-3 Products: Sensitivity Analysis Courtesy of Nadia Smith, University of Wisconsin, USA Grid SizeSampling PeriodViewing Angle 0 < VZA < 90 0 < VZA < 32 15 days 30 days 1 degree 2 degrees

14. EUMETSAT, July 2013 Coordination Group for Meteorological Satellites - CGMS Recommendations to CGMS-41

15. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS Action/recommendation The CRE-WG representatives and the members of its science advisory committee to prepare the Terms of References for a Clouds Working group within CGMS, following the recommendations made by the participants of the 4 th CREW workshop to be held in Grainau, Germany from 4–7 March 2014, for endorsement at CGMS-42. Proposal to CGMS

16. Agency, version?, Date 2012 Coordination Group for Meteorological Satellites - CGMS Cloud Retrieval Evaluation Workshop 2014 Image: Courtesy and Copyright by Alexander Riehn, Hotel am Badersee, Grainau 4-7 March 2014, Grainau, Germany, Europe Organized by the Deutscher Wetterdienst. Financially supported by EUMETSAT, the European Space Agency through the ESA Cloud CCI project and Deutscher Wetterdienst Program Committee Bryan Baum (co-chair), Rob Roebeling (co-chair), Ralf Bennartz, Ulrich Hamann, Andrew Heidinger, Jan Fokke Meirink, Martin Stengel, Andi Walther, and Anke Thoss Members of CGMS are cordially invited to attend this workshop.

17. EUMETSAT, July 2013 Coordination Group for Meteorological Satellites - CGMS Thank You