NOAA Coral Reef Watch is conducting research and development on the first product to use both satellite-derived light and temperature data to predict coral stress that leads to bleaching. The methodology uniquely expresses both thermal stress and excess-light stress as an equivalent light stress value, allowing the light and temperature data to be combined in a single product of stress on the coral photosystem, called the Light Stress Damage (LSD) product.

While mass coral bleaching has generally been predicted on the basis of excess thermal stress alone, it is actually the impact of high temperatures on the function of photosystems within the zooxanthellae that leads to bleaching.

The daily total photosynthetically active radiation (PAR) is determined from satellite-derived hourly snapshots of surface PAR. Due to the extreme temporal variability of light intensity at the sea surface, the daily PAR totals have significant errors. Given the strong dependence of the LSD product on these values, the stability of the PAR data will be closely monitored during the current experimental phase.