Great Barrier Reef sea surface temperature: longitudinal anomaly 1998-2024, 2050, 2080

The summer mean longitudinal Sea Surface Temperature anomaly represents the temperature difference of any single 5km pixel with the temperature summer mean across a latitudinal transect. We define refugia as areas where the SST is more than 1°C cooler than the surrounding waters during the warm season (January to March), using hourly SST data from our regional model. We calculate hourly SST anomalies at each location by removing the longitudinal averages along a transect from the coast to the open ocean. We first average SST values at each latitude at each hour along a longitudinal transect—from the coast to 200 km past the edge of the continental shelf (defined by the 200-m isobath). Next, we compare the SST at each grid point along the transect with this average to calculate an anomaly value. The SST anomaly is thus calculated as T' = T - Tbar. Here, T is the SST at each grid point, and Tbar is the SST averaged over the longitudinal transect. Summer is defined from 01-January to 31-March. The date of the product is referred to as the middle of the summer days, 15-February.