scholarly journals Frontal Waves in the East of the Tsugaru Strait Revealed by the High-Frequency Radar Observation

2021 ◽  
Author(s):  
Hitoshi KANEKO ◽  
Takahiro Tanaka ◽  
Hiroto Abe ◽  
Masahide Wakita ◽  
Ken’ichi Sasaki ◽  
...  
Keyword(s):  
High Frequency ◽  
Baroclinic Instability ◽  
Propagation Speed ◽  
Surface Velocity ◽  
Warm Current ◽  
High Frequency Radar ◽  
The North ◽  
Current Axis ◽  
Tsugaru Strait ◽  
Tsugaru Warm Current

Abstract Surface velocity observations of the eastern part of the Tsugaru Strait made by the high-frequency radar revealed frequent occurrence of frontal waves along the axis of the Tsugaru Warm Current in 2017–2019. The current axis (maximum of the zonal velocity in the meridional direction) disturbed in the north–south direction with period of ~ 13.7 days that is dominant timescale of tide modulation in the strait, in addition to that of ~ 27.3 days. The amplitude of the axis fluctuation increased in the downstream direction, from the eastern neck of the channel (~ 141.0°E) to the outlet of the strait adjacent to the Pacific Ocean (~ 141.5°E). The propagation speed of the disturbance was slower than that due to surface advection especially in the seasons when the stratification was developed, and agreed well with that estimated from the theory based on the two-layer baroclinic instability model except for winter. The north–south modulation of the axis at the outlet of the strait (~ 141.5°E) could cause short-term (from 20 days to 1 month) variations of an anticyclonic gyre of the Tsugaru Warm Current that is developed in the east of the outlet from summer to autumn reported by the previous studies.

scholarly journals Evidence of coastal trapped wave scattering using high-frequency radar data in the Mid-Atlantic Bight

2020 ◽  
Author(s):  
Kelsey Brunner ◽  
Kamazima M. M. Lwiza
Keyword(s):  
Empirical Orthogonal Function ◽  
High Frequency ◽  
Radar Data ◽  
Surface Velocity ◽  
Knowledge Gap ◽  
Eof Analysis ◽  
High Frequency Radar ◽  
Orthogonal Function ◽  
The North ◽  
Complex Empirical Orthogonal Function

Abstract. Coastal trapped waves (CTWs) become scattered when they encounter irregular coastlines and bathymetry during propagation. Analytical and modeling studies have provided some information about the different types of shelf geometries that can induce scattering, but much of the CTW scattering process generally remains a large knowledge gap. Furthermore, CTW scattering has never before been directly identified with observations. High-frequency radar surface velocity data covering the Mid-Atlantic Bight (MAB) continental shelf provides unprecedented observations of CTWs within a region with a highly complex coastline and bathymetry. A combination of velocity vector maps from real vector empirical orthogonal function (R-EOF) analysis and phase maps from complex empirical orthogonal function (C-EOF) analysis allow the identification of CTW scattering by assuming each EOF mode corresponds to a CTW mode. Abrupt jumps in phase in association with magnitude amplification/reduction or directional rotation of velocity vectors are indications of scattering. Using these guidelines, Georges Bank, Hudson Shelf Valley, Delaware Bay mouth, Chesapeake Bay mouth, and the North Carolina shelf are identified as high scattering regions within the MAB. Furthermore, stratification is confirmed to increase scattering into progressively higher order modes through a cascading process by comparing winter and summer cases, which supports previous theoretical and numerical model predictions. The simple methodology used here can be applied to observations of CTWs on other coastlines around the world to identify additional scattering regions and help close the knowledge gap.

scholarly journals Accelerated ocean acidification in the Tsugaru Strait by an intensified Tsugaru Warm Current

2020 ◽  
Author(s):  
Masahide Wakita ◽  
Ken'ichi Sasaki ◽  
Akira Nagano ◽  
Hiroto Abe ◽  
Takahiro Tanaka ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Warm Current ◽  
Tsugaru Strait ◽  
Tsugaru Warm Current

The role of an intense jet in the Tsugaru Strait in the formation of the outflow gyre revealed using high-frequency radar data

2021 ◽  
Author(s):  
Hitoshi Kaneko ◽  
Ken'ichi Sasaki ◽  
Hiroto Abe ◽  
Shuichi Watanabe ◽  
Yoshiaki Sato
Keyword(s):  
High Frequency ◽  
Radar Data ◽  
High Frequency Radar ◽  
Tsugaru Strait

scholarly journals A Vector Geometry–Based Eddy Detection Algorithm and Its Application to a High-Resolution Numerical Model Product and High-Frequency Radar Surface Velocities in the Southern California Bight

2010 ◽  
Vol 27 (3) ◽  
pp. 564-579 ◽  
Author(s):  
Francesco Nencioli ◽  
Changming Dong ◽  
Tommy Dickey ◽  
Libe Washburn ◽  
James C. McWilliams
Keyword(s):  
High Resolution ◽  
Numerical Model ◽  
High Frequency ◽  
Southern California ◽  
Velocity Fields ◽  
Southern California Bight ◽  
Surface Velocity ◽  
Physical Parameters ◽  
High Frequency Radar ◽  
Eddy Detection

Abstract Automated eddy detection methods are fundamental tools to analyze eddy activity from the large datasets derived from satellite measurements and numerical model simulations. Existing methods are either based on the distribution of physical parameters usually computed from velocity derivatives or on the geometry of velocity streamlines around minima or maxima of sea level anomaly. A new algorithm was developed based exclusively on the geometry of the velocity vectors. Four constraints characterizing the spatial distribution of the velocity vectors around eddy centers were derived from the general features associated with velocity fields in the presence of eddies. The grid points in the domain for which these four constraints are satisfied are detected as eddy centers. Eddy sizes are computed from closed contours of the streamfunction field, and eddy tracks are retrieved by comparing the distribution of eddy centers at successive time steps. The results were validated against manually derived eddy fields. Two parameters in the algorithm can be modified by the users to optimize its performance. The algorithm is applied to both a high-resolution model product and high-frequency radar surface velocity fields in the Southern California Bight.

Optimizing and Validating High-Frequency Radar Surface Current Measurements in the Mona Passage

2011 ◽  
Vol 45 (3) ◽  
pp. 49-58 ◽  
Author(s):  
Jorge E. Corredor ◽  
Andre Amador ◽  
Miguel Canals ◽  
Samuel Rivera ◽  
Jorge E. Capella ◽  
...  
Keyword(s):  
High Frequency ◽  
Surface Current ◽  
Acoustic Doppler Current Profiler ◽  
The United States ◽  
Repeated Measurements ◽  
Surface Velocity ◽  
High Frequency Radar ◽  
Detection And Tracking ◽  
Current Profiler ◽  
Mona Island

AbstractThe Mona Passage is a major shipping lane to the Panama Canal and a key route for illegal traffic into the United States. We have emplaced two high-frequency radar (HFR) stations on the west coast of Puerto Rico intended to allow mapping of the ocean surface velocity field of the eastern Mona Passage and to explore its performance in vessel detection and tracking. The array provides coverage of the southeastern quadrant of the Passage extending west to Mona Island and north to Rincon. Hourly results are posted online in near-real time. To optimize our results, we twice measured the antenna beam patterns and applied these corrections to the resulting radial returns. To assess the basic capability of the Mona Passage HFR array to measure surface currents in this tropical environment, we undertook validation measurements, including repeated deployment of Lagrangian drifters, deployment of an acoustic Doppler current profiler, and comparison with modeled tidal currents. Our experimental measurements showed good agreement to both modeled and in situ data lending confidence to the area-wide surface current maps generated by this system. Repeated measurements showed limited temporal variability of antenna distortion patterns, demonstrating that these are in large part the product of the surrounding environment. Comparison between a numerical particle tracking algorithm and experimental Lagrangian trajectories showed mixed results, with better agreement during periods of low intrahour variability in current direction than during periods of rapid tidal reversal.

Nonlinear interaction of the Tsugaru Warm Current and tide in the Tsugaru Strait

2012 ◽  
Vol 62 (6) ◽  
pp. 923-941 ◽  
Author(s):  
Ryota Wada ◽  
Takuji Waseda ◽  
Hirotada Nanjo
Keyword(s):  
Nonlinear Interaction ◽  
Warm Current ◽  
Tsugaru Strait ◽  
Tsugaru Warm Current

The role of an intense jet in the Tsugaru Strait in the formation of the outflow gyre revealed using high-frequency radar data

2021 ◽  
Author(s):  
Hitoshi Kaneko ◽  
Ken'ichi Sasaki ◽  
Hiroto Abe ◽  
Shuichi Watanabe ◽  
Yoshiaki Sato
Keyword(s):  
High Frequency ◽  
Radar Data ◽  
High Frequency Radar ◽  
Tsugaru Strait
Sign in / Sign up

Export Citation Format

Share Document