Remote Sensing

Remote sensing allows us to gather data on various properties of surface seawater using sensors on satellites orbiting the Earth. One key measurement is sea surface temperature (SST), which is determined by detecting the electromagnetic radiation emitted by the ocean in the infrared and microwave wavelengths. These measurements have been collected since the 1980s, providing a 40-year database that can be used to study climate change. By analysing this data, we can calculate temperature anomalies and track the occurrence, average duration (in days) and intensity of marine heatwaves. Additionally, electromagnetic radiation in the visible light spectrum helps us study the presence and ocean surface concentration of pigments, such as those used by microalgae for photosynthesis. This information is used to determine the chlorophyll-a concentration, which in turn helps estimate phytoplankton growth and primary production. Have a look at the different remote sensing products available below for Irish waters.

Sea Surface Temperature

Maps of sea surface temperature in the Irish EEZ from the Operational Sea Surface Temperature and Ice Analysis system run by the UK's Met Office and delivered by IFREMER. Data accessible from 1982 until present.

Sea Surface Temperature Anomaly

Maps of sea surface temperature anomaly from a 30-year (1993-2022) climatology, showing areas that are cooler or warmer than usual.

Marine Heat Waves

Maps of marine heat wave occurrence and intensity in the Irish EEZ. Due to global warming, the frequency, duration and intensity of marine heat waves have been increasing during the last decades.

Surface Temperature Historical

A tool to obtain SST time series (1982 - present) at a specific site of your choice, together with analysis of marine heat wave and cold spell occurrence. In addition, in-situ seawater temperature observations from the Irish Marine Data Buoy Observation Network, Mace Head and Deenish Island buoys are provided. Observations are downloadable as CSV files.

Chlorophyll-a Concentration

Last week's maps of surface chlorophyll-a in Irish coastal waters from satellite observations. Maps of chlorophyll-a anomalies are provided too. These provide information on phytoplankton growth and primary production.

Red Band Difference

The Red Band Difference (RBD) algorithm is used as a proxy of relative chlorophyll-a fluorescence and is calculated as the difference between two red bands. As described by Amin et al. (2009) and tested in Irish waters by Jordan et al. (2021), the RBD algorithm is less sensitive to coloured dissolved organic matter, suspended particulate matter and atmospheric corrections, which makes it useful in both open and coastal waters.