CMS Buoy Blacklist

1. CMS Buoy Blacklist S. Péré, A. Marsouin

2. Outline • Background • Method • Results • Conclusion OSI SAF Workshop, Lannion, 5-6 March 2013

3. basins used by Ostia METOP SST validation results showed an anomaly in summer 2009: observed on the global and North Pacific results OSI SAF Workshop, Lannion, 5-6 March 2013

4. SST anomaly was due to erroneous buoys Two sets of Technocean buoys were launched at the end of July 2009, showing a 2 to 3K negative bias => How to eliminate such buoys? …building a buoy blacklist OSI SAF Workshop, Lannion, 5-6 March 2013

5. Method: automatic scheme • Night time data • Satellites: METOP-2, NOAA-18, NOAA-19 METEOSAT, GOES-13 since 1st June 2011 • Automatic update on 5, 15, 25 of the month: process two successive 10-day periods buoy blacklisted if |bias| > 1.5C for 2 satellites on 1 period or 1 satellite on both period • Distributed every 10 days: • mailing list (initially MyOcean SST TAC members) • ftp://ftp.ifremer.fr/ifremer/cersat/projects/myocean/sst-tac/insitu/blacklist/ OSI SAF Workshop, Lannion, 5-6 March 2013

6. Method: interactive control • Every 3 months; at the begining of month N, months N-4, N-3, N-2 are checked • Information used: • SST plots derived from the CMS MDB • UKMO blacklist(and MF ARPEGE blacklist) • The blacklisted buoy period may be enlarged using: (SST plot only) or (SST plot and UKMO blacklist) • A buoy may be added to the blacklist if: blacklisted by UKMO and errors on SST plot, especially by day OSI SAF Workshop, Lannion, 5-6 March 2013

7. blacklisting period in situ METOP-2METEOSAT-9GOES-13 Example 1: an easy case for the automatic scheme OSI SAF Workshop, Lannion, 5-6 March 2013

8. Results after the interactive control: Results of the automatic scheme: night cases all cases Example 2: a case modified by the interactive control in situ METOP-2METEOSAT-9GOES-13 OSI SAF Workshop, Lannion, 5-6 March 2013

9. METEOSAT-9 & GOES-13 (with algorithm correction) How many buoys in the blacklist? Variations associated with the interactive control OSI SAF Workshop, Lannion, 5-6 March 2013

10. Buoys in METOP MDB over 3 monthsJuly-September 2012 (night) OSI SAF Workshop, Lannion, 5-6 March 2013

11. Blacklisted buoys over 3 months July-September 2012 OSI SAF Workshop, Lannion, 5-6 March 2013

12. OSI SAF Workshop, Lannion, 5-6 March 2013

13. Blacklisted buoys over 3 months July-September 2012 OSI SAF Workshop, Lannion, 5-6 March 2013

14. Buoy 43560 off California OSI SAF Workshop, Lannion, 5-6 March 2013

15. Comments • The automatic scheme uses very simple criteria how could it be improved? • A few buoys that should be blacklisted are missed in the automatic scheme => they are used in the OSI SAF operational validation (may perturb the day results) • These buoys are blacklisted by the interactive control => they are eliminated from the offline validation • Doing the interactive control is not very pleasant: handling of the data and of the many plots should be improved OSI SAF Workshop, Lannion, 5-6 March 2013

16. Conclusion • A buoy blacklist is routinely maintained at CMS • updated every 10 days • interactive control every 3 months, using UKMO blacklist • distributed to users • Blacklist characteristics • global, starting on 1 January 2009 • drifting buoys only • based on nighttime satellite data • main contributors: METOP, METEOSAT and GOES-E • Scheme could be improved… if somebody available OSI SAF Workshop, Lannion, 5-6 March 2013

17. UKMO blacklist summary • Global • Drifting buoys and ships • Based on OSTIA results, on a monthly basis: A buoy is rejected if: |mean (SSTOSTIA – SSTBUOY) | > 1.5 K or rms (SSTOSTIA – SSTBUOY) > 2.5 K with a minimum of 30 reports in the last month OSI SAF Workshop, Lannion, 5-6 March 2013

18. Blacklisted buoys July-September 2012 seen by METEOSAT-9 OSI SAF Workshop, Lannion, 5-6 March 2013