These along-track measurements are made by the Research Vessel Thomas G. Thompson and show the water temperature, salinity, and chlorophyll fluorescence at 5 meters depth. Salinity measures how how salty the water is. Chlorophyll fluorescence is an indicator of phytoplankton abundance. Phytoplankton are the microscopic plants that use sunlight and nutrients to grow. They form the base of the oceanic food chain. Watch the colors as they change on the ship's track and compare the colors to their values on the colorbar to the right of each plot.