1. Page 1 © Crown copyright 2004 Modern biases in in situ SST measurements John Kennedy, Nick Rayner, Philip Brohan, David Parker, Chris Folland, et al.

2. Page 2 © Crown copyright 2004 Summary  SST measurement methods.  Introduction to the SST record.  Biases associated with each method.  Impacts of measurement method on climate monitoring.

3. Page 3 © Crown copyright 2004 Measurement Methods

4. Page 4 © Crown copyright 2004 Relating Measurement Method to Bias.

5. Page 5 © Crown copyright 2004 SST (60˚N-60˚S) and uncertainties

6. Page 6 © Crown copyright 2004 Japanese and Dutch SSTs

7. Page 7 © Crown copyright 2004 American SSTs

8. Page 8 © Crown copyright 2004 The changing balance

9. Page 9 © Crown copyright 2004 Modern period 1970-2005  Metadata on measurement methods from  WMO publication 47 (1972-2005)  ICOADS.  VOSClim  WMO Pub. 47 being digitized back to 1953.  Kent, E. C., S. D. Woodruff and D. I. Berry, 2005: WMO Publication No. 47 Metadata and an Assessment of Observation Heights in ICOADS. Submitted to the Journal of Atmospheric and Oceanic Technology  Kent, E. C., and A. Kaplan, 2005: Towards Estimating Climatic Trends in SST, Part 3: Systematic Biases. Journal of Atmospheric and Oceanic Technology, in press

10. Page 10 © Crown copyright 2004 Buckets v ERI

11. Page 11 © Crown copyright 2004 Drifting Buoys vs Ships

12. Page 12 © Crown copyright 2004 A Plague of Buoys

13. Page 13 © Crown copyright 2004 Implications

14. Page 14 © Crown copyright 2004 SST drifter -SST ship (average 1990-2005)

15. Page 15 © Crown copyright 2004 Seasonal Cycle Difference ( ˚C )

16. Page 16 © Crown copyright 2004 Conclusions  There are biases in modern SST measurements  Current monitoring system is potentially good – random errors are small…  … but, errors due to biases are larger than random errors.  Predominance of buoys in recent data may be leading to an underestimate of warming.

17. Page 17 © Crown copyright 2004 Further Work (A)ATSR instruments 1991-2005 Buoy/Ship matchup database 1.3 Million ship-buoy pairs  Use VOSClim data

18. Page 18 © Crown copyright 2004 Questions and Answers