acquired April 9, 2013
download large image (4 MB, JPEG, 4240x4240)
acquired April 9, 2013
download GeoTIFF file (15 MB, TIFF)
acquired April 9, 2013
download Google Earth file (KML)
Editor’s Note: Today’s caption is the answer to Earth Observatory’s December puzzler.
Stretching from tropical Florida to the doorstep of Europe, this
river of water carries a lot of heat, salt, and history. The Gulf Stream
is an important part of the global ocean conveyor belt
that moves water and heat across the North Atlantic from the equator
toward the poles. It is one of the strongest currents on Earth, and one
of the most studied. It’s discovery is often attributed to Benjamin
Franklin, though sailors likely knew about the current long before they
had a name for it.
This image shows a small portion of the Gulf Stream as it appears in
infrared imagery. Data for this image was acquired on April 9, 2013, by
the Thermal Infrared Sensor (TIRS) on the Landsat 8
satellite. TIRS observes in wavelengths of 10.9 micrometers and 12.0
micrometers. The image above is centered at 33.06° North latitude,
73.86° West longitude, about 500 kilometers (300 miles) east of
Charleston, South Carolina. (The downloadable KML and GeoTIFF files will
allow you to see it on a map.)
“Infrared bands measure how much energy is emitted by the surface of
the Earth at particular wavelengths,” said Matthew Montanaro, a
researcher on NASA’s Landsat team. “We can calculate the surface
temperature from these measurements through math and some modeling.
Essentially, the higher the infrared signal measured, the higher
temperature on the surface. This allows researchers to get a measurement
of sea surface temperature without having to directly measure the water
temperature on site.
“For several locations around the world, however, there are floating
buoys that can directly measure the sea temperature,” he added. “We can
compare these buoy measurements with the TIRS image-derived temperatures
and adjust our calibration to provide a more accurate temperature
calculation for TIRS and other satellites.”
For a phenomenon such as the Gulf Stream, the sensitivity and
relatively high resolution of the TIRS instrument allows scientists to
tease out the micro structures within the much wider patterns. In the
image above, water temperatures range from 18° to 21.25° Celsius (64° to
70.25° Fahrenheit), with cooler temperatures in purple and the warmest
nearly white. Note how the Gulf Stream is not a uniform band, but
instead has finer streams and pockets of warmer and colder water. The
bright area in the lower right is likely caused by sunglint, the
reflection of sunlight directly back at the sensor from the ocean’s
surface.
Further Reading
- NASA Earth Observatory (2005, April 20) The Gulf Stream.
- NASA Earth Observatory (1999, August) On the Shoulders of Giants: Benjamin Franklin.
- NASA Earth Observatory (2000, June 28) The Temperature of the Gulf Stream.
- Rosentstiel School of Marine and Atmospheric Science (2013) Ocean Surface Currents: The Gulf Stream. Accessed December 21, 2013.
NASA Earth Observatory image by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey. Caption by Michael Carlowicz.
- Instrument:
- Landsat 8 - TIRS
NASA: A Lava Lamp Look at the Atlantic - 12.27.13
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