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No direct link between the North Atlantic Current and the New England Coastal Sea Surface

No direct link between the North Atlantic Current and the New England Coastal Sea Surface

As the North Atlantic Oscillation (NAO) changes, it affects the trade winds across the tropical Atlantic from the east. The higher the NAO, the stronger the trade wind than normal, which strengthens the Atlantic Meridional Overturning Circulation (AMOC). At the same time, the westerlies beyond New England are stronger than usual. The average sea level is reduced with abnormally high air pressure in the northeast coast. It is wind and pressure that cause two phenomena. Credits: Natalie Renier, Woods Hole Marine Research Institute

A new study by the Woods Hole Oceanographic Institution (WHOI) clarifies how the major tides in the North Atlantic Ocean affect the sea level in the northeastern United States. The study was published in the June 13 issue of the journal. Geophysical Research LettersReviewed oceanographic conveyance belts moving from the Atlantic Ocean to the north and cooler waters and record sea-level records of coastal New England.

"Scientists have discovered that if AMOCs are stronger in certain seasons or years, the sea level in the northeastern United States will be lowered," said Chris Piecuch, a WHOI physical oceanologist. Author of the paper. "For example, in the winter of 2009-2010, AMOC was weakened by about 30%, and at the same time our sea level increased by six inches." Sea level rise lasting for months can have serious coastal effects. "

"But it is unclear whether the two sources of coastal sea level and AMOC are linked to cause and effect," Piecuch added. It has been found that AMOC intensity and sea level change at the same time, but it has not been found to cause a direct change in behavior elsewhere. Instead, it seems to be controlled simultaneously by the volatility of major meteorological patterns in the North Atlantic, such as the North Atlantic Oscillation (NAO).

"Changes in the NAO change AMOC and sea level separately," says Piecuch. "When the NAO changes, it affects the trade winds across the tropical Atlantic from the east. When the NAO is high, the trade winds are stronger than normal and the AMOC is strengthened, but at the same time the winds of New England in the West are also stronger than usual and with the extraordinarily high pressure of the northeastern coast The average sea level is lowered, and both phenomena occur simultaneously due to wind and pressure. "

According to Piecuch, such a study was not possible until recently. Over the past few decades, satellite imagery has provided scientists with motion recordings on ocean surfaces, but could not detect currents below the surface. But since 2004, the international team of scientists has started to maintain a set of tools across the Atlantic Ocean between Florida and Morocco. Collectively, the so-called RAPID arrays have a variety of sensors that measure current, salinity, and temperature. "RAPID does not solve all the individual current details going on, but it gives us the sum of the ocean actions that AMOC represents," Piecuch says.

This discovery is especially important to the people of the Northeast Coast. Existing climate models say that sea level rise in the New England coast will be greater than the global average, although climate change will cause global sea level rise in the next century. Scientists have traditionally assumed that the future sea level rise in the northeastern United States is closely related to the deterioration of AMOC predicted by climate models. But according to the results, the family needs to be reconsidered, says Piecuch. "The current problem is that we have about 13 years of AMOC data to work with, so we need to wait a longer time to get a better understanding of how these two things are related to each other over the long term, He says.

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Additional information:
Christopher G. Piecuch et al., Is the New England coastal sea level related to the Atlantic meridional overturning circulation at 26 ° N? Geophysical Research Letters (2019). DOI: 10.1029 / 2019GL083073

Provided by
Woods Hall Marine Research Institute

North Atlantic Currents and New England Coastal Sea Level (June 14, 2019)
Searched for June 14, 2019
Source: https://phys.org/news/2019-06-link-north-atlantic-currents-sea.html

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