Identifying the shoreward Gulf Stream front at Cape Hatteras with Coastal Ocean Radar surface currents

2012 Oceans ◽  
2012 ◽  
Author(s):  
M. Muglia ◽  
H. Seim ◽  
S. Haines
Keyword(s):  
Gulf Stream ◽  
Coastal Ocean ◽  
Surface Currents ◽  
Cape Hatteras ◽  
Ocean Radar

On the flushing of Port Phillip Bay: an application of HF ocean radar

1999 ◽  
Vol 50 (6) ◽  
pp. 483 ◽  
Author(s):  
A. Prytz ◽  
M. L. Heron
Keyword(s):  
Numerical Models ◽  
Surface Current ◽  
Coastal Ocean ◽  
Current Data ◽  
Surface Currents ◽  
Tidal Forcing ◽  
Residual Currents ◽  
Tidal Component ◽  
The Matrix ◽  
Ocean Radar

HF ocean radar can produce maps of surface current in coastal ocean and estuarine waters by providing coverage in both the space and time dimensions. The deployment of COSRAD in Port Phillip Bay for two successive five-day periods provided hourly values of surface currents over the topographically complex area at the south end of the bay. Analysis of the current data provided tidal ellipses for the validation of numerical models, with resultant residual currents of the order of 0·05 m s–1. The repeated hourly maps were the basis for producing Lagrangian tracks; most tracks resulted in trapped paths which remained for long periods of time in the matrix of channels and sand-banks. A ‘tidal run’ technique was developed to calculate the length of Lagrangian tracks over one phase (ebb or flood) of the main tidal component. All tidal runs were about equal to, or shorter than, the length of the relevant channel; this indicates that tidal forcing is not effective in flushing the bay. In contrast, the observed residual currents can be an effective flushing agent if they persist for three days or longer. It is suggested that phenomena on the scale of meteorological to seasonal forcing are the effective flushing agents for Port Phillip Bay.

scholarly journals The Icelandic Low as a Predictor of the Gulf Stream North Wall Position

2016 ◽  
Vol 46 (3) ◽  
pp. 817-826 ◽  
Author(s):  
Alejandra Sanchez-Franks ◽  
Sultan Hameed ◽  
Robert E. Wilson
Keyword(s):  
Gulf Stream ◽  
Southern Oscillation ◽  
Time Lags ◽  
Grand Banks ◽  
The North ◽  
Cape Hatteras ◽  
Pressure Anomaly ◽  
Icelandic Low ◽  
North Wall ◽  
Wall Position

AbstractThe Gulf Stream’s north wall east of Cape Hatteras marks the abrupt change in velocity and water properties between the slope sea to the north and the Gulf Stream itself. An index of the north wall position constructed by Taylor and Stephens, called Gulf Stream north wall (GSNW), is analyzed in terms of interannual changes in the Icelandic low (IL) pressure anomaly and longitudinal displacement. Sea surface temperature (SST) composites suggest that when IL pressure is anomalously low, there are lower temperatures in the Labrador Sea and south of the Grand Banks. Two years later, warm SST anomalies are seen over the Northern Recirculation Gyre and a northward shift in the GSNW occurs. Similar changes in SSTs occur during winters in which the IL is anomalously west, resulting in a northward displacement of the GSNW 3 years later. Although time lags of 2 and 3 years between the IL and the GSNW are used in the calculations, it is shown that lags with respect to each atmospheric variable are statistically significant at the 5% level over a range of years. Utilizing the appropriate time lags between the GSNW index and the IL pressure and longitude, as well as the Southern Oscillation index, a regression prediction scheme is developed for forecasting the GSNW with a lead time of 1 year. This scheme, which uses only prior information, was used to forecast the GSNW from 1994 to 2015. The correlation between the observed and forecasted values for 1994–2014 was 0.60, significant at the 1% level. The predicted value for 2015 indicates a small northward shift of the GSNW from its 2014 position.

scholarly journals Loop Current Variability as Trigger of Coherent Gulf Stream Transport Anomalies

2019 ◽  
Vol 49 (8) ◽  
pp. 2115-2132 ◽  
Author(s):  
Joël J.-M. Hirschi ◽  
Eleanor Frajka-Williams ◽  
Adam T. Blaker ◽  
Bablu Sinha ◽  
Andrew Coward ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Gulf Stream ◽  
Time Lag ◽  
Ocean Model ◽  
Surface Velocity ◽  
Loop Current ◽  
Intrinsic Variability ◽  
Cape Hatteras ◽  
Florida Straits ◽  
Stream Transport

AbstractSatellite observations and output from a high-resolution ocean model are used to investigate how the Loop Current in the Gulf of Mexico affects the Gulf Stream transport through the Florida Straits. We find that the expansion (contraction) of the Loop Current leads to lower (higher) transports through the Straits of Florida. The associated surface velocity anomalies are coherent from the southwestern tip of Florida to Cape Hatteras. A simple continuity-based argument can be used to explain the link between the Loop Current and the downstream Gulf Stream transport: as the Loop Current lengthens (shortens) its path in the Gulf of Mexico, the flow out of the Gulf decreases (increases). Anomalies in the surface velocity field are first seen to the southwest of Florida and within 4 weeks propagate through the Florida Straits up to Cape Hatteras and into the Gulf Stream Extension. In both the observations and the model this propagation can be seen as pulses in the surface velocities. We estimate that the Loop Current variability can be linked to a variability of several Sverdrups (1Sv = 106 m3 s−1) through the Florida Straits. The exact timing of the Loop Current variability is largely unpredictable beyond a few weeks and its variability is therefore likely a major contributor to the chaotic/intrinsic variability of the Gulf Stream. However, the time lag between the Loop Current and the flow downstream of the Gulf of Mexico means that if a lengthening/shortening of the Loop Current is observed this introduces some predictability in the downstream flow for a few weeks.

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