Wind-induced interannual variability of sea level slope, along-shelf flow, and surface salinity on the Northwest Atlantic shelf

• Published in: Journal of Geophysical Research: Oceans
• Main Authors: Li, Yun, Ji, Rubao, Fratantoni, Paula S., Chen, Changsheng, Hare, Jonathan A., Davis, Cabell S., Beardsley, Robert C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley & Sons 2014
• Subjects: Wind; Sea level; Flow; Salinity; Interannual variability; Northwest Atlantic shelf; Newfoundland; Northwest Atlantic
• Online Access: https://hdl.handle.net/1912/6713

Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 119 (2014): 2462–2479, doi:10.1002/2013JC009385. In this study, we examine the importance of regional wind forcing in modulating advective processes and hydrographic properties along the Northwest Atlantic shelf, with a focus on the Nova Scotian Shelf (NSS)-Gulf of Maine (GoM) region. Long-term observational data of alongshore wind stress, sea level slope, and along-shelf flow are analyzed to quantify the relationship between wind forcing and hydrodynamic responses on interannual time scales. Additionally, a simplified momentum balance model is used to examine the underlying mechanisms. Our results show significant correlation among the observed interannual variability of sea level slope, along-shelf flow, and alongshore wind stress in the NSS-GoM region. A mechanism is suggested to elucidate the role of wind in modulating the sea level slope and along-shelf flow: stronger southwesterly (northeastward) winds tend to weaken the prevailing southwestward flow over the shelf, building sea level in the upstream Newfoundland Shelf region, whereas weaker southwesterly winds allow stronger southwestward flow to develop, raising sea level in the GoM region. The wind-induced flow variability can influence the transport of low-salinity water from the Gulf of St. Lawrence to the GoM, explaining interannual variations in surface salinity distributions within the region. Hence, our results offer a viable mechanism, besides the freshening of remote upstream sources, to explain interannual patterns of freshening in the GoM. This work was supported by NOAA’s Fisheries and the Environment Program, Grant #12-03 and through NOAA Cooperative Agreement NA09OAR4320129. 2014-10-16