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. Anomalies from years 1998, 2002, 2016, 2017, 2020.2022, 2023, 2024 were calculated using actual NOAA CRW SST. Anomalies from 2050-59 and 2080-89 were calculated using hourly SST data from our regional model.夏季平均经向海表温度距平（longitudinal Sea Surface Temperature anomaly）指任意5km分辨率像素的温度，与该纬向断面（latitudinal transect）上的夏季平均温度之间的差值。我们将避难生境定义为：在暖季（1月至3月），海表温度（Sea Surface Temperature, SST）较周边水域低1℃以上的区域，所用数据为我们区域模式输出的逐小时海表温度资料。 我们通过扣除沿某一断面的纬向平均温度，计算每个位置的逐小时海表温度距平。该断面从海岸延伸至远海：首先，对每小时沿该经向断面（从海岸至大陆架边缘外200km，大陆架边缘以200米等深线（200-m isobath）划定）上各纬度的海表温度进行平均；随后，将断面上每个网格点的海表温度与该平均值进行对比，以计算距平值。海表温度距平的计算公式为T' = T - T̄，其中T为单个网格点的海表温度，T̄为该经向断面上的平均海表温度。本研究中夏季定义为1月1日至3月31日，该产品的日期对应夏季中旬，即2月15日。 1998年、2002年、2016年、2017年、2020年、2022年、2023年及2024年的距平值采用美国国家海洋和大气管理局珊瑚礁观测系统（National Oceanic and Atmospheric Administration Coral Reef Watch, NOAA CRW）的实际海表温度数据计算得到；2050-2059年及2080-2089年的距平值则通过我们的区域模式输出的逐小时海表温度资料计算得到。