Summer Degree Heating Days for Coral Bleaching Risk Since 2012

Summer Degree Heating Days (DHD) calculated from daily positive sea surface temperature anomalies (SSTa) for the Great Barrier Reef region. DHD values are accumulated from December 1 to April 30 each year since 2012, using climatologies from 1993-2003 or 2002-2011. The magnitude of DHD correlates with past coral bleaching events.

Use Cases

• Analyze the correlation between Degree Heating Days (DHD) magnitude and historical coral bleaching event records.
• Map spatial patterns of thermal stress using the high-resolution, satellite-derived Sea Surface Temperature (SST) product.
• Compare DHD calculations based on the two different climatology periods (1993-2003 and 2002-2011) for trend analysis.
• Identify areas with frequent missing data due to cloud cover by analyzing grid cells left blank in the SST product.

Strengths

• Provides data for every summer season from December 2012 to April 2026, offering over a decade of temporal coverage.
• Based on a high-resolution, state-of-the-art satellite SST product from the Integrated Marine Observing System (IMOS).
• Explicitly documents the methodology for handling missing data due to cloud cover by leaving grid cells blank.

Limitations

• Data availability is spatially inconsistent due to cloud cover, resulting in missing values for affected grid cells.
• The dataset is derived from a now-decommissioned system (ReefTemp Next Generation), which may affect long-term continuity.
• File formats are limited to HTML, PNG, and PDF, which are not ideal for large-scale quantitative analysis without data extraction.

Provenance

Source

Australian Ocean Data Network, derived from the Bureau of Meteorology's ReefTemp Next Generation system.

Collection Method

Calculated by accumulating daily positive Sea Surface Temperature anomalies (SSTa) from IMOS 1-day L3S night-only SST satellite product.

Time Range

Summer seasons from December 1, 2012, to April 30 annually.

Freshness

Last updated on March 20, 2026.

Geography

Great Barrier Reef region, Australia.