The Evolving Sea Surface Temperature SST Record from

The Evolving Sea Surface Temperature (SST) Record from ICOADS Scott Woodruff, NOAA/ESRL Richard W. Reynolds, NOAA/NCDC Elizabeth C. Kent, UK NOCS Steven J. Worley, NCAR “Climate Variability and Extremes During the Past 100 Years” Gwatt, Switzerland, 24 -26 July 2006 Dec 1942

Aim • Review current status and future challenges of global SST data ü Focus: in situ & 20 th Century Outline • Evolution of… ü SST observing system ü ICOADS (SST plus other variables) ü product development • Future directions

Evolving…SST observing sys • Brussels 1853 Maritime Conf. ü Voluntary Observing Ships • Buoys & other automated Ocean Data Acquisition Systems (ODAS): 1970 s • Joint WMO-IOC Technical Commission ü Formed: 1999

Recent SST Adequacy: GCOS Essential Climate Variable (ECV) WCRP WGASF: net heat flux to 10 W/m 2 per 5 box § Best observed ECV § Only ECV to have improved in data quality since 1980’s § Highly complex data mixture, even recently

Historical SST Sources [Bucket photos courtesy of David Parker, Met Office]

Modern SST sources Not in ICOADS - GHRSST Pilot Project: for satellite SST

Observing System (OS) Changes SST per 2 box per month 45% of possible 2° boxes have 5 samples/month in the 70 -80’s Decreasing low counts due to reduced ships observations Increasing high counts due to high frequency sampling from buoys

OS changes: % at UTC obs time US GMN obs 6 -hrly ships > buoy reports

Evolving…ICOADS International Comprehensive Ocean-Atmosphere Data Set • Cooperative NOAA-NCAR project - Releases: ü 1: 1854 -1979 (done 1985) ü 2. 3: 1784 -2005 (done 2006) • SST plus other variables • Delayed-mode (DM) data ü Ship & ocean profile temps. (≤ 3 m): thru 1997 ü Buoys: thru 2004 • Real-time (GTS) only: for 2005

1900 -09 SST obs per 2 box per decade 1920 -29 1940 -49 1960 -69 by R 2. 3 (2006) 1980 -89 2000 -05 R 1 (1985) R 2 (2002)

Platform Mix: 1936 -2005 > GTS drifter reports consolidated in DM

VOS Metadata Blend: WMO Pub. 47 (~annual) Declining VOS… [With Liz Kent & Dave Berry, UK NOCS] Reports with metadata

Benefits from DM Data and Metadata: SST method indicator GTS format Logbook format WMO Pub. 47 intake bucket bait tanks therm. bucket condenser intake bucket hull contact sensor trailing thermistor intake/inlet other hull contact “through hull” ”through hull" radiation therm. bait tanks therm. trailing thermistor others other (footnote) plus: sst. D (depth) Potential usage in bias adjustments to help improve the long-term climate change record

Evolving… SST Product Development • ICOADS monthly summaries (2 /1 - unanalyzed) ü No bias adj. (Worley et al. , Woodruff et al. , 2005) • Blended satellite + in situ, e. g. : • • NOAA OI. v 2 (Reynolds et al. , 2002) (new Oct ‘ 06) Historical reconstructions, e. g. : ü NOAA ERSST. v 2 (Smith & Reynolds, 2004) ü Had. ISST 1. 1, Had. SST 2 (Rayner et al. , 2003, 2005) ü Kaplan et al. (1998), Ishii et al. (2005), etc.

SST: Dec 1942 ICOADS Had. ISST ERSST

Nighttime Zonal Bias: AVHRR - Had. SST 2 90 N AVHRR Pathfinder: Reanalysis: w/ residual 90 S problems 90 N AVHRR Operational: seasonal cycle of biases in mid latitudes '82 '05 90 S In situ data remain vital for bias-adjusting the satellite data (including GHRSST-PP)

Future Directions • Digitization & blending of new data/metadata • Improved QC and bias adjustments • Availability of other ECVs in ICOADS to validate SST (e. g. , AT) • Improved climate-quality analyses • Accelerating international SST efforts

Digitize & Blend New Data

SST Bias Example: Bucket vs. Intake SST Historical Metadata are Critical • VOS: back to 1955 (blended for 1973 -) • ODAS metadata: fragmented/missing – New JCOMM/China meta-database

Recent SST Biases: Ship and Buoy Differences • Buoy SST colder than ship (mixed sensors) • More buoys later: increasing bias • Southern Oceans: drifting buoys • Tropics: + TAO • OI. v 2 similar to ship+buoy

META-T Pilot Project • JCOMM Workshop to establish a Pilot Project for the collection of real-time (RT) metadata re SST and temperature profiles (March 2006, UK) • Goals: ü Facilitate use of ocean temp. data ü Harmonize ocean & met-ocean practices ü Seeking agreed formats & practices

Conclusions SST Observing System: high level of heterogeneity ICOADS: widely used, but declining NOAA budgets Product developments: ICOADS is critical foundation Future: More data, bias adj. , climate-quality analyses International efforts: GHRSST-PP, META-T, etc. CLIMAR-III: 3 rd JCOMM Workshop on Advances in Marine Climatology Planned for Early 2008

Links and References icoads. noaa. gov ioc. unesco. org/jcomm/ www. ghrsst-pp. org • • Ishii, M. , A. Shouji, S. Sugimoto, and T. Matsumoto, 2005: Objective analyses of seasurface temperature and marine meteorological variables for the 20 th century using ICOADS and the Kobe Collection. Int. J. Climatol. (CLIMAR-II Special Issue), 25, 865 -879 (DOI: 10. 1002/joc. 1169). Kaplan, A. , M. A. Cane, Y. Kushnir, A. C. Clement, M. B. Blumenthal, and B. Rajagopalan, 1998: Analysis of global sea surface temperature 1856 -1991. J. Geophys. Res. , 103(C 9), 18567 -18589. Rayner, N. A. , D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent, and A. Kaplan, 2003: Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res. , 108(D 14), 4407, doi: 10. 1029/2002 JD 002670. Rayner, N. A. , P. Brohan, D. E. Parker, C. K. Folland, J. J. Kennedy, M. Vanicek, T. J. Ansell, and S. F. B. Tett, 2006: Improved analyses of changes and uncertainties in sea surface temperature measured in situ since the mid-nineteenth century: The Had. SST 2 dataset. J. Climate, 19, 446 -469. Reynolds, R. W. , N. A. Rayner, T. M. Smith, D. C. Stokes, and W. Wang, 2002: An improved in situ and satellite SST analysis for climate. J. Climate, 15, 1609 -1625. Smith, T. M. , and R. W. Reynolds, 2004: Improved extended reconstruction of SST (18541997). J. Climate, 17, 2466 -2477. Woodruff, S. D. , H. F. Diaz, S. J. Worley, R. W. Reynolds, and S. J. Lubker, 2005: Early ship observational data and ICOADS. Climatic Change, 73, 169 -194. Worley, S. J. , S. D. Woodruff, R. W. Reynolds, S. J. Lubker, and N. Lott, 2005: ICOADS Release 2. 1 data and products. Int. J. Climatol. (CLIMAR-II Special Issue), 25, 823 -842 (DOI: 10. 1002/joc. 1166).