FAQ + Support

What is SST?

SST stands for Sea Surface Temperature. The readings you see on the chart are a good estimate of the temperature of water above the thermocline.

Why do I see no data for a part of the globe?

There are two main reasons for missing data: cloud cover and time. Because clouds obscure satellite view of the ocean, any area covered by clouds when the satellite passed over will have no data. The exception is SST from GHRSST which uses microwave band imaging (that can see through clouds) and buoy data to fill gaps hidden by clouds. In addition to cloud cover, the time of observation is important to what data you see. The satellites we use are polar orbiting and image the globe roughly once each day. There will be data missing if you are looking at an area that the satellite hasn't imaged yet. Additionally, satellites sometimes stop imaging while correcting their orbits, some data sources may be missing for long periods of time.

Why the odd date/time ranges?

Each data source covers the globe once each day from midnight to midnight UTC. The time range displayed in the chart caption is that UTC day displayed in your local time.

Which data source is best?

More recent data is better: for most parts of the globe, the menu of data source options is ordered from first to arrive to last to arrive for any given day. The AVHRR sources are lower resolution than all other sources. GHRSST is the highest quality SST reading; it incorporates many sources including buoys and through-cloud microwave imaging.

How often is the data chart updated?

Temperature, chlorophyll, and true-color data are updated approximately every half hour. You can refresh a data chart by switching briefly to another data chart.

How accurate is the bathymetry data?

The bathymetry data we use is for anglers to estimate the locations of major undersea features. It should never be used as a reference for safe navigation at sea. The data is derived directly from NOAA's ETOPO global relief model, the International Hydrographic Organization's General Bathymetric Chart of the Oceans (GEBCO), and the Shuttle Radar Topography Mission (SRTM15+). These are all research sources, not navigational references. Only official government charts and notices to mariners contain the information needed for safe navigation.

How accurate are the legal boundaries?

EEZ and administrative boundaries are updated on a best effort basis and may have errors. Only official government charts mark true legal boundaries.