Clouds of sediment colored the Gulf of Mexico on November 10, 2009, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this photo-like image. Much of the color likely comes from resuspended sediment dredged up from the sea floor in shallow waters. The sediment-colored water transitions to clearer dark blue near the edge of the continental shelf, where the water becomes deeper.
The ocean turbulence that brought the sediment to the surface is readily evident in the textured waves and eddies within the tan and green waters. Tropical Storm Ida had come ashore over Alabama and Florida, immediately east of the area shown here, a few hours before the image was acquired. The storm’s wind and waves may have churned up waters farther west.
A second source of sediment is visible along the shore. Many rivers, including the Mississippi River, drain into the Gulf of Mexico in this region. The river plumes are dark brown that fade to tan and green as the sediment dissipates. According to the National Climate Data Center, October 2009 was the wettest October in the 115-year weather record for the south-central United States, which includes the area shown in this image. Rivers throughout the region ran high, likely carrying more sediment than usual into the Gulf.
The rivers also carry nutrients like iron from soil and nitrogen from fertilizers. These nutrients fuel the growth of phytoplankton, tiny, plant-like organisms that grow in the ocean surface waters. Phytoplankton blooms color the ocean blue and green and may be contributing to the color seen here.
The large image provided above is the highest-resolution version of the image available. The image is available in additional resolutions from the MODIS Rapid Response System.
NASA images courtesy Jeff Schmaltz, MODIS Rapid Response Team at NASA GSFC. Caption by Holli Riebeek, NASA’s Earth Observatory.