About the sea surface temperature timeseries graphs

Analyses available

Sea Surface Temperature (SST) timeseries are available from 1900 for a number of regions around Australia and globally. These timeseries include ocean surface temperatures only and do not include any land surface temperatures.

SST timeseries are presented as anomalies or departures from the climatological average. This is because temperature anomalies tend to be more consistent throughout wide areas than absolute temperature values. SST timeseries anomalies relative to the 1961–1990 and 1991–2020 periods are presented.

Mean sea surface temperature values are provided for a boxed region around Australia (from 4°S to 46°S and from 94°E to 174°E), as well as for six regions within this box: the Northern Tropics (4°S–22°S, 94°E–174°E), the Southern Region (30°S–46°S, 94°E–174°E), the Southwest Region (22°S–46°S, 94°E–116°E), the Northwest Region (4°S–22°S, 94°E–130°E), the Coral Sea (4°S–26°S, 142°E–174°E) and the Tasman Sea (26°S–46°S, 150°E–174°E). Values are also provided for the Great Barrier Reef (see below for details).

These regions are the same as those used to provide trend maps on these pages.

Timeseries are determined for the seven regions shown above

The above areas have been chosen for analysis since they are large enough to contain a meaningful climatology and not be influenced by data and interpolation errors. At the same time, these areas are small enough to provide a meaningful representation of regional climate influences around the Australian continent.

Great Barrier Reef

In addition to the larger boxed areas shown above, timeseries are also produced for the Great Barrier Reef. This is calculated from the average of seven grid points that are in or close to the Great Barrier Reef Marine Park. Only seven points can be used because the underlying data is on a relatively coarse grid, of 2° (about 220 km) resolution. This also means that small scale features may not be fully resolved. NOAA note that ERSST is most suitable for long-term global and basin-wide studies, and that should be considered when using the timeseries presented here.

The seven grid points used for the Great Barrier Reef timeseries

Data used

Since December 2017, the sea surface temperature timeseries are calculated from the NOAA Extended Reconstructed Sea Surface Temperature Version 5 (ERSST v5) data provided by the NOAA/OAR/ESRL PSL, Boulder, Colorado, USA. A full description of the ERSST v5 data can be found in Huang et al., (2017), with the earlier ERSST v4 described in Huang et al., (2015) and Liu et al., (2015).

The ERSST v5 dataset metadata catalogue entry and identifier is doi:10.7289/V572FNM.

Changes from v4 to v5 include the use of new data sources (such as Argo floats above 5 meters) and new versions of input datasets, such as ICOADS R3.0 and HadISST2 sea ice concentration. Improved methodologies have been applied, such as the inclusion of additional statistical modes, less spatial-temporal smoothing, better quality control method, and bias correction with baseline to modern buoy observations. The new version improves the spatial structures and magnitudes of El Nino and La Nina events.

Between November 2016 and March 2020 the ERSST v5 dataset was impacted by the reduction of the number of drifting buoy reports into the ICOADS Near-Real-Time product (R3.0.1). This was noted on the NOAA ICOADS website. In March 2020 an updated dataset (ICOADS 3.0.2) that incorporates more complete drifting buoy reports was implemented into ERSSTv5. Data since 2008 have been changed.

Please note that any use of the data analysed on these web pages should be acknowledged to the Bureau of Meteorology. Apart from the purposes of study, research, criticism and review, no part of these data may be reproduced, or redistributed for any commercial purposes, or distributed to a third party for such purpose, without written permission from the Director of Meteorology.

The actual data values used to produce each graph are available via the "Raw dataset" link. The format for these data is:

    <start year><start month><end year><end month>   <mean temperature anomaly (°C)>

The "Sorted dataset" link provides the timeseries as a sorted list in order to place recent values in historical context.

Further information

Huang, B., P.W. Thorne, V.F. Banzon, T. Boyer, G. Chepurin, J. Lawrimore, M.J. Menne, T.M. Smith, R.S. Vose and H.-M. Zhang, 2017: Extended Reconstructed Sea Surface Temperature version 5 (ERSST.v5): Upgrades, validations and intercomparisons. Journal of Climate doi:10.1175/JCLI-D-16-0836.1

Huang, B., V.F. Banzon, E. Freeman, J. Lawrimore, W. Liu, T.C. Peterson, T.M. Smith, P.W. Thorne, S.D. Woodruff and H.-M. Zhang, 2015: Extended Reconstructed Sea Surface Temperature version 4 (ERSST.v4): Part I. Upgrades and intercomparisons. Journal of Climate 28:3, 911-930 doi:10.1175/JCLI-D-14-00006.1

Liu, W., B. Huang, P.W. Thorne, V.F. Banzon, H.-M. Zhang, E. Freeman, J. Lawrimore, T.C. Peterson, T.M. Smith and S.D. Woodruff, 2015: Extended Reconstructed Sea Surface Temperature version 4 (ERSST.v4): Part II. Parametric and structural uncertainty estimations. Journal of Climate 28:3, 931-951 doi:10.1175/JCLI-D-14-00007.1

Great Barrier Reef features and park boundary spatial data provided by the Spatial Data Centre of the Great Barrier Reef Marine Park Authority. For more information or further spatial data, contact gis@gbrmpa.gov.au