As the nutrient‐rich subsurface slope water intruding into the deep basin of the Gulf of Maine (GoM) supports the high biological productivity in the semi‐enclosed gulf, it is important to understand the process and time scale of such slope water intrusion. This study focuses on variations of the GoM deep water on seasonal to interannual time scales and the influences of open ocean processes on the temporal variation of the deep water properties. Based on long‐term monitoring data, it is found that the deep water at Jordan Basin (one of three major basins in the GoM) is persistently warmer in winter than in summer, which is distinctly different from the seasonality of surface water in the basin and the deep water on neighboring shelf seas. The unique seasonality in the deep GoM reflects a time‐lagged response to shoreward intrusion of the subsurface slope water off the GoM. Both observation‐based lag‐correlation analyses and numerical simulations confirm a timescale of approximately 3 months for the intruding subsurface slope water to flow from Northeast Channel to Jordan Basin. Properties of the intruding slope water at the Northeast Channel were significantly correlated with the Gulf Stream position and dramatically impacted by episodic warm‐core rings shed from Gulf Stream. Inside the deep GoM, the intruding slope water was also indirectly affected by the fresher water input from Nova Scotia Current. Spreading of the fresher water inside the gulf strengthens near‐surface stratification, suppresses deep convection, and preserves heat and salt in the deep GoM during the wintertime.
High-frequency internal waves and thick bottom mixed layers observed by gliders in the Gulf Stream: GULF STREAM GLIDERS
- Award ID(s):
- 1633911
- NSF-PAR ID:
- 10028285
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 44
- Issue:
- 12
- ISSN:
- 0094-8276
- Page Range / eLocation ID:
- 6316 to 6325
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
Abstract The Gulf Stream affects global climate by transporting water and heat poleward. The current’s volume transport increases markedly along the U.S. East Coast. An extensive observing program using autonomous underwater gliders provides finescale, subsurface observations of hydrography and velocity spanning more than 15° of latitude along the path of the Gulf Stream, thereby filling a 1500-km-long gap between long-term transport measurements in the Florida Strait and downstream of Cape Hatteras. Here, the glider-based observations are combined with shipboard measurements along Line W near 68°W to provide a detailed picture of the along-stream transport increase. To account for the influences of Gulf Stream curvature and adjacent circulation (e.g., corotating eddies) on transport estimates, upper- and lower-bound transports are constructed for each cross–Gulf Stream transect. The upper-bound estimate for time-averaged volume transport above 1000 m is 32.9 ± 1.2 Sv (1 Sv ≡ 106 m3 s−1) in the Florida Strait, 57.3 ± 1.9 Sv at Cape Hatteras, and 75.6 ± 4.7 Sv at Line W. Corresponding lower-bound estimates are 32.3 ± 1.1 Sv in the Florida Strait, 54.5 ± 1.7 Sv at Cape Hatteras, and 69.9 ± 4.2 Sv at Line W. Using the temperature and salinity observations from gliders and Line W, waters are divided into seven classes to investigate the properties of waters that are transported by and entrained into the Gulf Stream. Most of the increase in overall Gulf Stream volume transport above 1000 m stems from the entrainment of subthermocline waters, including upper Labrador Sea Water and Eighteen Degree Water.more » « less
-
The most famous ocean current, the Gulf Stream, is part of a large system of currents that brings warm water from Florida to Europe. It is a main reason for northwestern Europe’s mild climate. What happens to the warm water that flows northward, since it cannot just pile up? It turns out that the characteristics of the water change: in winter, the ocean warms the cold air above it, and the water becomes colder. Cold seawater, which is heavier than warm seawater, sinks down to greater depths. But what happens to the cold water that disappears from the surface? While on a research ship, we discovered a new ocean current that solves this riddle. The current brings the cold water to an underwater mountain ridge. The water spills over the ridge as an underwater waterfall before it continues its journey, deep in the ocean, back toward the equator.more » « less
