Page 1 © Crown copyright 2004 Modern biases in in situ SST measurements John Kennedy, Nick Rayner, Philip Brohan, David Parker, Chris Folland, et al.
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.
Page 3 © Crown copyright 2004 Measurement Methods
Page 4 © Crown copyright 2004 Relating Measurement Method to Bias.
Page 5 © Crown copyright 2004 SST (60˚N-60˚S) and uncertainties
Page 6 © Crown copyright 2004 Japanese and Dutch SSTs
Page 7 © Crown copyright 2004 American SSTs
Page 8 © Crown copyright 2004 The changing balance
Page 9 © Crown copyright 2004 Modern period Metadata on measurement methods from WMO publication 47 ( ) ICOADS. VOSClim WMO Pub. 47 being digitized back to 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
Page 10 © Crown copyright 2004 Buckets v ERI
Page 11 © Crown copyright 2004 Drifting Buoys vs Ships
Page 12 © Crown copyright 2004 A Plague of Buoys
Page 13 © Crown copyright 2004 Implications
Page 14 © Crown copyright 2004 SST drifter -SST ship (average )
Page 15 © Crown copyright 2004 Seasonal Cycle Difference ( ˚C )
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.
Page 17 © Crown copyright 2004 Further Work (A)ATSR instruments Buoy/Ship matchup database 1.3 Million ship-buoy pairs Use VOSClim data
Page 18 © Crown copyright 2004 Questions and Answers