Chlorophyll is the green pigment in plants and algae that is vital for photosynthesis. This is also what can give the Chesapeake Bay a greenish color during the summer, when the microscopic plants (called phytoplankton) are the most abundant in the Bay water. The Chesapeake Bay Hypoxia Forecast model simulates the growth and decay of these phytoplankton and estimates the amount of chlorophyll in the water.
The amount of chlorophyll in the water varies by a large amount both seasonally and with location in the Bay. The below maps show the estimated amount of chlorophyll in the water in terms of milligrams of chlorophyll per cubic meter of water (mg/m3, weight of chlorophyll per volume of water), with blue colors indicating less chlorophyll and red colors more chlorophyll. Gray lines on the maps contour 0.01, 0.1, 1, and 10 mg/m3 to help the eye gauge values. The maps show: