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 and coastal New England sea level records from the Atlantic to the north and cooler waters.
"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 coastal sea level and AMOC are connected by cause and effect," Piecuch adds. 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.
Cooperation in this study was supported by WHOI's Glen G. Gawarkiewicz and Jiayan Yang; Sönke Dangendorf University of Siegen in Germany; Atmospheric Environment Research (Christopher M. Little and Rui M. Ponte at Atmospheric and Environmental Research, Inc.)
The study was supported by National Science Foundation OCE-1558966, OCE-1834739 and OCE-1805029. NASA agreement NNH16CT01C; J. Lamar Worzel Assistant Scientist Fund and Penzance Endowed Fund to assist auxiliary scientists in the Woods Hole Oceanographic Institution.