This colourful radar image captured by the Copernicus Sentinel-1 mission features New Orleans and the delta of the Mississippi River, one the largest rivers in North America.
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The Mississippi River is one of the world’s major river systems in size, habitat diversity and biological productivity. It is a classic example of a meandering alluvial river with its loops and curls along its path. The nutrient-rich soil from sediment deposits carried by the Mississippi and its tributaries in the floodplain supports a variety of cropland.
The area pictured here shows the last segment of its 3766-km-long path, where the Mississippi passes through the city of New Orleans and empties into the Gulf of Mexico in a vast delta, known as the ‘bird-foot’ delta because of the shape created by the channels extending outward.
The size of the delta is due to sediment deposition over millions of years. The tonnes of sediment carried by the river system created the wetlands in southern Louisiana, which are home to many endangered species.
This image combines three radar acquisitions from Sentinel-1 taken two months apart from February to June 2026, with each image assigned to a different colour channel – red for February, green for April and blue for June. When overlapped, the bright resulting colours indicate changes on the ground that have occurred over time.
Water bodies, including the snaking Mississippi and the inland lakes, appear mostly black as smooth water surfaces reflect the radar signal away from the satellite. In the Gulf of Mexico, on the other hand, the mix of colours denotes changes on the surface, caused by wind or currents between each acquisition.
If we take a closer look, we can see ships in the gulf and on the Mississippi, as sparkling, multi-coloured dots, with the colour corresponding to the date of acquisition. Ships captured in February appear in red, those from April in green, and those from June in blue.
Shades of grey indicate areas with no or very little changes, such as the conurbation of New Orleans, which appears bright grey or white along the southern shore of Lake Pontchartrain, the largest inland lake in the image. Visible as thin, straight lines, several bridges cross the lake, notably the Pontchartrain Causeway right at the centre, which is recognised as the world’s longest continuous bridge over water.
Patches of neon green, pink and reddish colours can be seen to the west and south of New Orleans, marking the areas where the landscape changed considerably between winter and summer. Green zones indicate vegetation that sprouted, grew densest or experienced higher moisture levels in April, while pink and reddish tones highlight regions where ground conditions or vegetation growth were strongest during February.
Such radar images are invaluable for agriculture and environmental monitoring, allowing scientists to track seasonal crop growth, soil moisture, and the health of wetlands. The latter are extremely important, particularly in low-lying coastal areas such as New Orleans, as they also help protect the mainland from severe weather threats.