April 15, 2023 - Spring Thaw across the Great Lakes
Great Lakes
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The spring thaw was sweeping across the Great Lakes of the United
States and Canada in mid-April 2023. The Moderate Resolution Imaging
Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a
true-color image of the seasonal shift on April 13.
A distinct snowline stretches across the image, marking the boundary
between warmer air and ground temperatures and the remaining wintery
chill. Snow has vanished from most of the ground south of the
Canada-United States border, except for the northern portion of
Minnesota, Wisconsin, and the Upper Peninsula of Michigan, all south of
Lake Superior. No ice remains on any of the Great Lakes—not
particularly surprising since ice was scarce all winter. According to
the U.S. National Ice Center, the Great Lakes experienced maximum ice
coverage for the 2022-2023 ice season on February 4. At that time, the
coverage was estimated to be approximately 23. 35%, which is
significantly lower than the average maximum of 53% and occurred
approximately one month earlier than normal.
Lake Erie stands out among the five Great Lakes, wearing a bright wash
of milky blues and greens. The colorful swirls may originate from
several sources, such as sediment carried into the lake from rivers and
streams. Strong spring winds sometimes churn the water strongly enough
to pull sand and silt from the bottom of shallow Lake Erie, where it
then floats in suspension. The chalky color may even be due to a
whiting event, which is triggered when changes in water chemistry allow
the naturally-occurring calcium carbonate normally dissolved in the
lake water to precipitate (change into solid form) and become visible.
Finally, the greenish tones are suggested of microscopic algae
(phytoplankton) blooms, which frequently occur in the lake, but
normally emerge as water warms in the summer.
Image Facts
Satellite: Terra
Date Acquired: 4/13/2023
Resolutions: 1km (2.5 MB), 500m (7.6 MB), 250m (14.7 MB)
Bands Used: 1,4,3
Image Credit: MODIS Land Rapid Response Team, NASA GSFC
https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2023-04-15
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