About the average sea surface temperature maps
Analyses available
Annual and seasonal average sea surface temperature (SST) maps are available for the Australian region. Long-term averages have been calculated over the standard 30-year period 1961-1990. A 30-year period is used as it acts to largely smooth out the year-to-year variations of climate.
Interpreting the analyses
The average SST maps can be used in conjunction with the trend maps to provide an indication of how a trend compares to the long-term average. Due to the uncertainty of the interpolations procedure, data on or very near coastlines should be treated with some caution.
Data used
The SST average maps are calculated using the NOAA Extended Reconstructed Sea Surface Temperature Version 6 (ERSSTv6) dataset, provided by the NOAA National Centers for Environmental Information (NCEI), USA. ERSSTv6 is a global monthly analysis of SSTs on a 2° x 2° latitude‐longitude grid, suitable for long-term global and ocean-basin studies.
The average maps show annual and seasonal mean SSTs calculated over the standard 30-year climatological period 1961‐1990. This period is used to provide a consistent reference for describing long-term average conditions.
ERSSTv6 incorporates observations from ships, drifting and moored buoys, and Argo profiling floats. Its input data include the International Comprehensive OceanAtmosphere Data Set (ICOADS) Release 3.0.2, Argo observations from the Argo Global Data Assembly Centre, and sea-ice concentration data from HadISST2 for 1850‐2015 and NCEP from 2016 onwards.
Compared with ERSSTv5, ERSSTv6 introduces an artificial neural network (ANN) interpolation method to improve the reconstruction of sea surface temperatures and their spatial and temporal variability. Other improvements include a nearest-neighbour check in the quality control of ship observations, a large-scale filter applied to SST super-observations, and an updated algorithm for estimating sea surface temperatures in ice-covered regions.
The transition from ERSSTv5 to ERSSTv6 results in some changes to reconstructed historical sea surface temperatures. Consequently, the average values shown on these maps may differ slightly from previously published maps based on ERSSTv5.
Further information
The ERSSTv6 dataset is publicly available from the NOAA NCEI data archive.
Huang, B., X. Yin, T. Boyer, C. Liu, M. Menne, Y. D. Rao, T. Smith, R. Vose and H.-M. Zhang, 2025: Extended Reconstructed Sea Surface Temperature Version 6 (ERSSTv6): Part I. An Artificial Neural Network Approach. Journal of Climate, 38, 11051121. doi.org/10.1175/JCLI-D-23-0707.1
Huang, B., X. Yin, T. Boyer, C. Liu, M. Menne, Y. D. Rao, T. Smith, R. Vose and H.-M. Zhang, 2025: Extended Reconstructed Sea Surface Temperature Version 6 (ERSSTv6): Part II. Upgrades on Quality Control and Large-scale Filter. Journal of Climate, 38, 11231136. doi.org/10.1175/JCLI-D-24-0185.1
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
