People have long noticed that the water near Cabo Frio is unusually cool. When European explorers first surveyed the coastline of what is now the state of Rio de Janeiro in the early 15th century, they saw white sandy beaches, turquoise waters, shallow lagoons and lush mountains rising from the sea. However, there is one area where the water is so cool that the southeastern Brazilian headland pictured above was named "Cabo Frio," which means "Cold Cape" in Portuguese.
On September 16, 2023, Landsat 9's OLI-2 (Land Imager-2) captured this image of Cabo Frio's diverse coastline. The map (below) shows that surface water temperatures near Cabo Frio were lower that day than in surrounding waters. This situation is common: cold water rising to the surface from the depths of the ocean often lowers the surface temperature of Cabo Frio by several degrees.
The map's data comes from MURSST (Multiscale Ultra-Resolution Sea Surface Temperature), a temperature analysis conducted by a team at NASA's Jet Propulsion Laboratory. MURSST incorporates sea surface temperature measurements from NASA, NOAA and multiple international satellites, as well as ship and buoy observations. The terrain in the map is a digital elevation model created using observational data from the Shuttle Radar Topography Mission (SRTM).
The power behind Cabo Frio's unique climate
This upwelling is caused primarily by prevailing winds, strong northeasterly winds that blow along the coast much of the year, but especially in spring and summer, pushing warm surface water away from the coast. This allows cold water deep in the ocean to replenish and rise to the surface. The upwelling water is usually rich in nutrients and promotes the growth of phytoplankton, which in turn nourishes the marine ecosystem and promotes a bumper harvest for the Cabo Frio fishery.
A Cabo Frio upwelling model built by researchers in Germany and Brazil showed that the cold water zone typically covers an area about 200 kilometers long and 20 kilometers wide (124 miles long by 12 miles wide), with temperature gradients as high as 8 degrees Celsius (14 degrees Fahrenheit) in less than 10 kilometers. The findings are based in part on wind speed measurements from NASA's QuikSCAT satellite, which were also included in the analysis.
The first use of the name "Cabo Frio" appears on the Kunstmann III chart, the oldest known nautical chart containing lines of latitude. The map dates back to 1506, possibly earlier, and is thought to be based in part on the South American expeditions led by Portuguese explorer Gonçalo Coelho and Italian navigator Amerigo Vespucci.
NASA Earth Observatory image taken by Lauren Dauphin using Landsat data from the U.S. Geological Survey and data from the Multiscale Ultra-Resolution (MUR) project.
Compiled source: ScitechDaily