Chilling Out in Brazil
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- cabofrio_oli2_2023259_lrg.jpg (4497x2998, JPEG)
- cabofrio_mur_2023259.jpg (720x545, JPEG)
Metadata
- Sensor(s):
- Landsat 9 - OLI-2
- NOAA-15 POES - AVHRR
- Terra - MODIS
- Aqua - AMSR-E
- Aqua - MODIS
- NOAA-19 POES - AVHRR
- NOAA-18 POES - AVHRR
- Data Date: September 16, 2023
- Visualization Date: December 20, 2023
When European explorers first surveyed the coastline of what is now the state of Rio de Janeiro in the early 1500s, they encountered white sands, turquoise waters, shallow lagoons, and lush green mountains rising from the sea. The waters in one area, however, were unusually cool—so much so that the promontory in southeastern Brazil shown above was named Cabo Frio, Portuguese for “Cape Cold.”
The OLI-2 (Operational Land Imager-2) on Landsat 9 captured this image of Cabo Frio’s diverse coastline on September 16, 2023. The map (below) shows that surface waters that day were cooler off of Cabo Frio than in the surroundings waters. The pattern is common: Upwelling of cold water from deeper in the ocean to the surface often chills Cabo Frio’s surface waters by several degrees.
Data for the map come from MUR SST (Multiscale Ultrahigh Resolution Sea Surface Temperature), a temperature analysis from a team at NASA’s Jet Propulsion Laboratory. MUR SST blends measurements of sea surface temperatures from multiple NASA, NOAA, and international satellites, as well as ship and buoy observations. The terrain in the map is from a digital elevation model made with observations from the Shuttle Radar Topography Mission (SRTM).
The upwelling is primarily caused by the prevailing winds. Strong northeasterly winds that blow along the coast for much of the year—especially in the spring and summer—push warm surface waters away from the shore. This allows cool waters from deeper in the ocean to rise to the surface. Upwelled water is typically rich in nutrients that fuel populations of phytoplankton, which in turn nourish marine ecosystems and contribute to Cabo Frio’s productive fisheries.
One model of Cabo Frio upwelling, developed by researchers in Germany and Brazil, indicates that the zone of cool water typically covers an area about 200 kilometers long and 20 kilometers wide (124 miles long and 12 miles wide), and has temperature gradients as large as 8 degrees Celsius (14 degrees Fahrenheit) over less than 10 kilometers. The findings were based in part on wind speed measurements from NASA’s QuikSCAT satellite that were incorporated into the analysis.
The first known use of the name “Cabo Frio” appears on Kunstmann III, the oldest known nautical chart that includes lines of latitude. The map, which dates to 1506 or possibly earlier, is thought to be based partly on expeditions to South America led by the Portuguese explorer Gonçalo Coelho and Italian navigator Amerigo Vespucci.
References
- Calil, P., et al. (2021) Filaments, Fronts and Eddies in the Cabo Frio Coastal Upwelling System, Brazil. Fluids, 6(2), 54.
- Castelao, R. & Barth, J., (2006) Upwelling around Cabo Frio, Brazil: The importance of wind stress curl. Geophysical Research Letters, 33(3).
- Mazzini, P. & Barth, J., (2013) A comparison of mechanisms generating vertical transport in the Brazilian coastal upwelling regions. JGR Oceans, 118(11), 5977-5993.
- McIntosh, G. & Gaspar, J., (2020) Kunstmann III: The Oldest Known Nautical Chart Incorporating Latitudes. The International Journal for the History of Cartography, 33(3).
- NASA Scientific Visualization Studio (2003) Cold water upwelling. Accessed December 21, 2023.
- NOAA (2023) What is upwelling? Accessed December 21, 2023.
- Souza, B., et al, (2013) Toponymy and Historical Cartography: the legacy of geographic names on city of Cabo Frio—RJ. Accessed December 21, 2023.
- Virginia Institute of Marine Science (2013) Upwelling off the Brazilian coast. Accessed December 21, 2023.
NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey and data from the Multiscale Ultrahigh Resolution (MUR) project. Story by Adam Voiland.
This image record originally appeared on the Earth Observatory. Click here to view the full, original record.