Please use the IMAGE GALLERIES drop-down menu above to access the SATELLITE IMAGES for the year(s) of interest.
The satellite images were taken with the Moderate Imaging Spectoradiometer (MODIS) on the NASA satellites, Terra and Aqua. Imagery from 2009 onwards was prepared by Dr. Karen J. Scott and is consistent with previous images prepared by Dr. Greg McCullough (University of Manitoba) between 2003 and 2007. That is, the tone curve has been changed to emphasize colour differences in the lake.
Water bodies, such as Lake Winnipeg, contain particles (silt and clay), dissolved substances and living organisms(algae). These constituents, as well as the water itself, absorb and scatter light. This affects both the transparency (how clear the water is) and colour of the water. In these images, clear water (with few particles) will appear dark blue-black since most of the light is absorbed and a small amount of light (of the visible colour) is reflected. For example, very dark brown water is due to high concentrations of dissolved organic carbon, much like a cup of strong, black tea. Increasing inorganic particle concentration will cause a range of colours from blue to green to tan. The south basin of Lake Winnipeg often appears tan in colour due to high turbidity caused by particles carried in from the Red River, as well as high winds which stir up the sediment from the bottom of the lake. Highly turbid water due to an algal bloom will appear bright green in colour due to the algal cells at the surface of the lake. The edges of a bloom will appear crisp in the image when the bloom is at the surface of the lake, and less defined when it is below the surface of the lake.