Image:
This radar image from the Copernicus Sentinel-1 mission captures Buenos Aires, the capital of Argentina, the surrounding countryside and the Rio de la Plata estuary.
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This is a composite of three Sentinel-1 acquisitions taken in January, March and May this year, with each image assigned to a different colour channel (blue in January, green in March and red in May). As the environmental changes on the ground created a significant ‘backscatter’ reflection of the radar signal, they show up as bright shades that correspond to changes across the seasons.
On the right-hand side of the image, the metropolitan area of Buenos Aires is visible in light grey. The area has a population of more than 16 million people and lies at 25 m above sea level. The urban areas were largely unchanged between January and May, hence the lack of colour in this part of the image. Other towns, such as Luján and Junin, are also visible as smaller patches of grey west of the capital.
The blue areas correspond to surface changes such as choppy water, captured in January, which is mid-summer in Argentina. The rivers, deltas and open water are mainly coloured in either dark blue, purple or black. Winds and rough sea conditions during both January and May mean that the Rio de la Plata estuary, east of Buenos Aires, appears purple (a mix of blue in January and red in May). The Paraná river meanders through wetlands on the left of the image before flowing into the Rio de la Plata. The Uruguay river is also seen flowing from the north into the estuary.
To the west of Buenos Aires, agricultural fields and the Argentinean Pampas dominate the landscape. The green tint is due to significant ‘backscatter’ reflection of the radar signal in this area during the capture in March. Since this period is late summer in Argentina, it likely denotes growth of major crops such as soy and corn.
At the top of the image, a large area north of the Paraná river, in Entre Ríos province, appears in vivid red – the channel assigned to ground change in May, which is late Autumn in Argentina. It is likely that this is due to natural vegetation growth caused by seasonal rains during that period. This is when the areas of exposed grassland come back to life following the long, dry summers.