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Results and Actions from the 2nd Cloud Cloudworkshop, Locarno 2009

Results and Actions from the 2nd Cloud Cloudworkshop, Locarno 2009. Anke Thoss, Rob Roebeling and Andi Walther. Introduction. Introduction Groups, Products and Satellites Evaluation method Results Conclusions. 2. Introduction: 1 st Cloud Workshop. History

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Results and Actions from the 2nd Cloud Cloudworkshop, Locarno 2009

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  1. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Results and Actions from the 2nd Cloud Cloudworkshop, Locarno 2009 Anke Thoss, Rob Roebeling and Andi Walther

  2. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Introduction Introduction Groups, Products and Satellites Evaluation method Results Conclusions 2

  3. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Introduction: 1st Cloud Workshop History First workshop was held in 2006 in Norrkoping, Sweden. Objective To asses the differences between algorithms to detect clouds and retrieve cloud properties from SEVIRI. Method For a single observation SEVIRI cloudmask and cloud properties of 12 algorithms were inter-compared. Recommendations • To validate passive imager cloud retrievals against CLOUDSAT/CALIPSO data; • To include cloud products from polar satellites (e.g. MODIS, AVHRR); • To organize next workshop within 2 year. 3

  4. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Introduction: 2nd Cloud Workshop Objectives • To inter-compare SEVIRI cloud properties retrievals from different retrieval algorithms; • To inter-compare cloud properties retrievals from different satellites; • To compare passive imager cloud properties retrievals to an independent set of cloud property measurements with superior quality. 4

  5. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Groups, Products and Satellites 5

  6. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 2nd Cloud Workshop: Introduction Data: i) 13 June 2008 (12:00 -15:30 hr)* ii) 17-18 June 2008 ( 22:00 - 01:45 hr)iii) 22 June 2008 (10:00 – 12:30 hr)iv) 3 July 2008 (10:00 - 12:00 hr) Algorithms: • 14 algorithms Satellites (Passive Imagers): • SEVIRI, MODIS, AVHRR, AIRS and POLDER Satellites used for validation: • Cloudsat, Calipso and AMSR * used for comparison study

  7. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 2nd Cloud Workshop: Groups Table: List of groups that provided data for the comparison

  8. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 2nd Cloud Workshop: Products Table: List of products included in the comparison study

  9. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 2nd Cloud Workshop: Provided data Table: List of products provided by each group x = MSG;o= MODIS;a= AVHRR;p= POLDER;ai=AIRS(REFerence data: cc = Cloudsat/Calipso; am = AMSR)

  10. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Evaluation Method 10

  11. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Evaluation Method SEVIRI Inter-comparison • Full disk images and statistics • Scatterplots and frequency distributions Comparison against MODIS Level 2 data • Scatterplots and statistics Comparison against A-Train sensors • Selection 5 region CUTs representing different conditions • Statistics of cloud properties from satellite for the region CUTs • CTH passive imagers (MSG, MODIS, AVHRR, AIRS) against Calipso • LWP passive imagers (MSG, MODIS, AVHRR) against AMSR

  12. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Region CUTs 6: Frontal clouds NH 3: Deep Convection 2: Stratocumulus 5: Frontal clouds SH 4: Multilayer clouds over ocean Fig. : Region CUTs selected to the comparison against A-Train sensors

  13. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Example: A-Train comparison (CTH) Along track statistics of Calipso and Cloudsat observed and SEVIRI retrieved CTH, and SEVIRI retrieved CTT and % water clouds. The statistics are only given in case all algorithms detected clouds. The bias, RMSE and correlation are given relative to Calipso or Cloudat observations. Fig. : Comparison of AWG (University of Wisconsin-Madison) cloud properties Cloud Top Height, Cloud Optical Depth, Cloud Effective Radius and Liquid Water Path with CLOUDSAT, MODIS and AMSR-E (CUT-05)

  14. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Results

  15. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Example: MSG inter-comparison MPEF CM used Variations in mean cloudiness 41% - 60% Fig. : Cloud masks of 12 MSG algorithms

  16. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Clear High Medium Low Controversial Example: MSG inter-comparison Fig. : Cloud top pressure of 12 MSG algorithms

  17. EUMETSAT 28th SWG-STG Meeting, 09 March 2010

  18. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Example: MSG inter-comparison Fig. : Cloud thermodynamic phase of 11 MSG algorithms

  19. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 A-Train Calipso/CPR - SEVIRI comparison CTH (CUT 5) Fig. : Comparison of Calipso and CLOUDSAT Cloud Top Height against the SEVIRI mean. The grey areas indicate the min/max of 12 SEVIRI retrievals (CUT-05)

  20. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Statistics region CUT 05

  21. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Taylor diagrams SEVIRI –CALIOP CTH

  22. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Taylor diagrams SEVIRI –CPR CTH

  23. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 A-Train comparison particle size (CUT 5) Fig. : Comparison of CLOUDSAT backscatter profile against the SEVIRI mean effective particle radius. The grey areas indicate the min/max of 7 SEVIRI retrievals (CUT-05)

  24. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 A-Train comparison particle size (CUT 2)

  25. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 A-Train comparison Cloud Optical Depth (CUT 5) Fig. : Comparison of CLOUDSAT backscatter profile against the SEVIRI mean cloud optical depth. The grey areas indicate the min/max of 7 SEVIRI retrievals (CUT-05)

  26. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 A-Train AMSR – SEVIRI LWP comparison Fig. : Comparison of AMSR and SEVIRI mean retrievals of LWP. The grey areas indicate the min/max of 4 SEVIRI retrievals (CUT-05)

  27. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Statistics region CUT 05

  28. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Statistical parameters of LWP to observations of AMSR-E

  29. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Individual cloud mask | Common cloud mask Generation of Level 3 products

  30. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Conclusions

  31. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Conclusions 1 • For homogeneous water clouds reasonable agreement (CTH, COD, REFF and LWP) • For homogeneous ice clouds good agreement for CTH and fair agreement for IWP and REFF • Generally good CTH agreement with CALIOP and CPR for opaque medium and high level clouds • Large differences in Cloud Phase results • Large differences for multiple layer clouds, some algorithms tend towards the top layer and others towards the bottom layer • Large differences for broken clouds

  32. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Conclusions 2 • Even single day inter-comparisons help to trace errors in processing and weak points of algorithms (one scheme resubmitted, lots of algorithm improvements after first cloud workshop) • Large differences in Level 2 cloud products due to selection of cloudy pixels has big influence on level 3 products! • Considerable variations between algorithms in CTP/COD histograms (ISCCP type diagrams)

  33. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 What is Next? EUMETSAT Fellowship EUMETSAT granted the fellowship: Evaluating present-day cloud parameter retrievals with state of art instruments from space (CLOUDSTATE). Period One year with possible extension to three years. Start 2010. Objective To evaluate the strengths and weaknesses of state of art passive imager cloud properties retrievals from MSG-SEVIRI, MODIS and AVHRR, and quantify in-situ (level 2) errors and uncertainties, and how these errors and uncertainties translate to the level 3 climatologies.

  34. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 EUMETSAT Fellowship: Plans Data • Simulated reflectances: From MSG- or Earthcare simulator. • Passive imagers: MSG, AVHRR, MODIS, … retrievals from ~15 algorithms for simulated reflectances and “golden days” • Reference data: Cloudsat, Calipso, AMSR, … Method • Comparison of retrievals from simulated reflectances. • Inter-comparison of retrievals for “golden days” (level 2). • Validation of retrievals against reference data (level 2) (exploit Cloudsat/Calipso products further (mask, phase, LWP/IWP) & exploit all available days . • Evaluation and optimization of level 3 products. • Feedback through mid-term cloud workshop.

  35. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 MSG Simulator RACMO 0.6 mm SEVIRI 0.6 mm RACMO 1.6 mm SEVIRI 1.6 mm

  36. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Method: comparison against reference data The reference data will be used to: • Investigate differences per climate region(land,sea, tropical, semi-arid and mid-lat) • Investigate differences per cloud condition(multiple layer, phase, 3-D structure) • Investigate possibilities to improve retrievals by combining different methods • Define a standard procedure to derive level-3 products

  37. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Planning Year 1 (2010) • Level 2: (inter)comparison of simulated retrievals • Level 2: (inter)comparison of golden days retrievals • Comparison Paper Year 2 (2011) • Level 3: Product comparison • Prepare and organize mid-term cloud workshop • Incorporate findings of the mid-term cloud workshop Year 3 (2012) • Research standard procedures to derive Level 3 products • Investigate manners to combine strong points of algorithms • Paper & Final report

  38. EUMETSAT 28th SWG-STG Meeting, 09 March 2010 Thank you!

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