The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Robert S. Pickart - One of the best experts on this subject based on the ideXlab platform.
-
Cyclonic eddies in the West Greenland Boundary Current System
Journal of Physical Oceanography, 2021Co-Authors: Astrid Pacini, Robert S. Pickart, Isabela A. Le Bras, Fiammetta Straneo, N. Penny Holliday, M.a. SpallAbstract:AbstractThe Boundary Current system in the Labrador Sea plays an integral role in modulating convection in the interior basin. Four years of mooring data from the eastern Labrador Sea reveal persistent mesoscale variability in the West Greenland Boundary Current. Between 2014 and 2018, 197 mid-depth intensified cyclones were identified that passed the array near the 2000 m isobath. In this study, we quantify these features and show that they are the downstream manifestation of Denmark Strait Overflow Water (DSOW) cyclones. A composite cyclone is constructed revealing an average radius of 9 km, maximum azimuthal speed of 24 cm/s, and a core propagation velocity of 27 cm/s. The core propagation velocity is significantly smaller than upstream near Denmark Strait, allowing them to trap more water. The cyclones transport a 200-m thick lens of dense water at the bottom of the water column, and increase the transport of DSOW in the West Greenland Boundary Current by 17% relative to the background flow. Only a portion of the features generated at Denmark Strait make it to the Labrador Sea, implying that the remainder are shed into the interior Irminger Sea, are retroflected at Cape Farewell, or dissipate. A synoptic shipboard survey east of Cape Farewell, conducted in summer 2020, captured two of these features which shed further light on their structure and timing. This is the first time DSOW cyclones have been observed in the Labrador Sea—a discovery that could have important implications for interior stratification.
-
Cyclonic eddies in the West Greenland Boundary Current system
2021Co-Authors: Astrid Pacini, Robert S. Pickart, Isabela A. Le Bras, Fiammetta Straneo, N. Penny Holliday, Michael A. SpallAbstract:<p>The Labrador Sea is an important site for deep convection, and the Boundary Current surrounding the Sea impacts the strength of this convection and the subsequent restratification. As part of the Overturning of the Subpolar North Atlantic Program, ten moorings have been maintained on the West Greenland shelf and slope that provide hourly, high-resolution renderings of the Boundary Current. These data reveal the presence and propagation of abundant mid-depth intensified cyclonic eddies, which have not previously been documented in the West Greenland Boundary Current system. This study quantifies these features and their structure and demonstrates that they are the downstream manifestation of Denmark Strait Overflow Water (DSOW) cyclones. Using the mooring data, the statistics of these features are presented, a composite eddy is constructed, and the velocity and transport structure are described. A synoptic survey of the region captured two of these features, and provides further insight into their structure and timing. This is the first time DSOW cyclones have been observed in the Labrador Sea, and their presence, propagation, and transport must be accounted for in order to assess their contribution to the heat and freshwater budgets of the Labrador Sea interior.</p>
-
The Atlantic Water Boundary Current north of Svalbard in late summer
Journal of Geophysical Research: Oceans, 2017Co-Authors: M. Dolores Pérez-hernández, Robert S. Pickart, Daniel J. Torres, Vladimir Pavlov, Kjetil Våge, Randi Ingvaldsen, Arild Sundfjord, Angelika H. H. Renner, Svetlana Y. ErofeevaAbstract:Data from a shipboard hydrographic/velocity survey carried out in September 2013 of the region north of Svalbard in the Nansen Basin are analyzed to characterize the Atlantic Water (AW) Boundary Current as it flows eastward along the continental slope. Eight meridional transects across the Current, spanning an alongstream distance of 180 km, allow for a detailed description of the Current and the regional water masses. During the survey the winds were light and there was no pack-ice. The mean section reveals that the Boundary Current was O(40 km) wide, surface-intensified, with a maximum velocity of 20 cm/s. Its mean transport during the survey was 3.11 ± 0.33 Sv, of which 2.31 ± 0.29 Sv was AW. This suggests that the two branches of AW entering the Arctic Ocean via Fram Strait—the Yermak Plateau branch and the Svalbard branch—have largely combined into a single Current by 30°E. At this location the Boundary Current meanders with a systematic change in its kinematic structure during offshore excursions. A potential vorticity analysis indicates that the flow is baroclinically unstable, consistent with previous observations of AW anticyclones offshore of the Current as well as the presence of a near-field cyclone in this data set. Our survey indicates that only a small portion of the Boundary Current is diverted into the Kvitoya Trough (0.17 ± 0.08 Sv) and that the AW temperature/salinity signal is quickly eroded within the trough.
-
The Atlantic Water Boundary Current in the Nansen Basin: Transport and mechanisms of lateral exchange
Journal of Geophysical Research: Oceans, 2016Co-Authors: Kjetil Våge, Robert S. Pickart, Daniel J. Torres, Vladimir Pavlov, Randi Ingvaldsen, Arild Sundfjord, Peigen Lin, Andrey ProshutinskyAbstract:Data from a shipboard hydrographic survey near 30°E in the Nansen Basin of the Arctic Ocean are used to investigate the structure and transport of the Atlantic Water Boundary Current. Two high-resolution synoptic crossings of the Current indicate that it is roughly 30 km wide and weakly mid-depth intensified. Using a previously-determined definition of Atlantic Water, the transport of this water mass is calculated to be 1.6 ± 0.3 Sv, which is similar to the transport of Atlantic Water in the inner branch of the West Spitsbergen Current. At the time of the survey a small anti-cyclonic eddy of Atlantic Water was situated just offshore of the Boundary Current. The data suggest that the feature was recently detached from the Boundary Current, and, due to compensating effects of temperature and salinity on the thermal wind shear, the maximum swirl speed was situated below the hydrographic property core. Two other similar features were detected within our study domain, suggesting that these eddies are common and represent an effective means of fluxing warm and salty water from the Boundary Current into the interior. An atmospheric low pressure system transiting south of our study area resulted in southeasterly winds prior to and during the field measurements. A comparison to hydrographic data from the Pacific Water Boundary Current in the Canada Basin under similar atmospheric forcing suggests that upwelling was taking place during the survey. This provides a second mechanism related to cross-stream exchange of heat and salt in this region of the Nansen Basin. This article is protected by copyright. All rights reserved.
-
seasonal to interannual variability of the pacific water Boundary Current in the beaufort sea
Progress in Oceanography, 2014Co-Authors: Eric T Brugler, Robert S. Pickart, G W K Moore, Steven Roberts, Thomas J Weingartner, Hank StatscewichAbstract:Abstract Between 2002 and 2011 a single mooring was maintained at the core of the Pacific water Boundary Current in the Beaufort Sea, approximately 150 km east of Pt. Barrow, Alaska. Using velocity and hydrographic data from six year-long deployments, we examine the variability of the Current on seasonal to interannual timescales. The seasonal signal is characterized by enhanced values of volume, heat, and freshwater transport during the summer months associated with the presence of two summertime Pacific water masses, Alaskan Coastal Water and Chukchi Summer Water. Strikingly, over the decade the volume transport of the Current has decreased by more than 80%, with comparable reductions in the heat and freshwater transports, despite the fact that the flow through Bering Strait has increased over this time period. The largest changes in the Boundary Current have occurred in the summer months. Using atmospheric reanalysis fields and weather station data, we demonstrate that an increase in summer easterly winds along the Beaufort slope is the primary cause for the reduction in transport. The stronger winds are due to an intensification of the summer Beaufort High and deepening of the summer Aleutian Low. Using additional mooring and shipboard data in conjunction with satellite fields, we investigate the implications of the reduction in transport of the Boundary Current. We argue that a significant portion of the mass and heat passing through Bering Strait in recent years has been advected out of Barrow Canyon into the interior Canada Basin – rather than entering the Boundary Current in the Beaufort Sea – where it is responsible for a significant portion of the increased sea ice melt in the basin.
Stephanie Waterman - One of the best experts on this subject based on the ideXlab platform.
-
mixing nonlocality and mixing anisotropy in an idealized western Boundary Current jet
Journal of Physical Oceanography, 2017Co-Authors: Ru Chen, Stephanie WatermanAbstract:AbstractMotivated by the key role of western Boundary Currents in shaping water mass distribution and gyre water exchanges, this study characterizes mixing in an idealized western Boundary Current jet using a barotropic quasigeostrophic model with numerical particles deployed. Both the nonlocality of mixing, depicted by nonlocality ellipses, and mixing anisotropy, depicted by mixing ellipses, are estimated. Mixing is more nonlocal within the jet compared to the jet flanks. In general, the size of nonlocality ellipses, a metric of the degree of mixing nonlocality, scales with the eddy velocity magnitude and the equilibration time for diffusivity. The tilt and eccentricity of the nonlocality ellipses, a characterization of the anisotropy of mixing nonlocality, agree with those of momentum flux ellipses in the regions where mixing nonlocality is small. Mixing ellipse characteristics are flow regime dependent. In regions dominated by wave radiation, the mixing ellipses align with the contours of the wave stre...
-
Deep Boundary Current disintegration in Drake Passage
Geophysical Research Letters, 2014Co-Authors: J. Alexander Brearley, K. L. Sheen, Alberto C. Naveira Garabato, David A. Smeed, Kevin Speer, Andeaus M. Thurnherr, Michael M. Meredith, Stephanie WatermanAbstract:The fate of a deep Boundary Current that originates in the Southeast Pacific and flows southward along the continental slope of South America is elucidated. The Current transports poorly ventilated water of low salinity (a type of Pacific Deep Water, PDW), into Drake Passage. East of Drake Passage, the Boundary Current breaks into fresh anticyclonic eddies, nine examples of which were observed in mooring data from December 2009 to March 2012. The observed eddies appear to originate mainly from a topographic separation point close to 60°W, have typical diameters of 20–60 km and accompanying Rossby numbers of 0.1–0.3. These features are likely to be responsible for transporting PDW meridionally across the Antarctic Circumpolar Current, explaining the near homogenization of Circumpolar Deep Water properties downstream of Drake Passage. This mechanism of Boundary Current breakdown may constitute an important process in the Southern Ocean overturning circulation.
-
Eddy Shape, Orientation, Propagation, and Mean Flow Feedback in Western Boundary Current Jets
Journal of Physical Oceanography, 2013Co-Authors: Stephanie Waterman, Brian J. HoskinsAbstract:AbstractThis manuscript revisits a study of eddy–mean flow interactions in an idealized model of a western Boundary Current extension jet using properties of the horizontal velocity correlation tensor to diagnose characteristics of average eddy shape, orientation, propagation, and mean flow feedback. These eddy characteristics are then used to provide a new description of the eddy–mean flow interactions observed in terms of different ingredients of the eddy motion. The diagnostics show patterns in average eddy shape, orientation, and propagation that are consistent with the signatures of jet instability in the upstream region and wave radiation in the downstream region. Together they give a feedback onto the mean flow that gives the downstream character of the jet and drives the jet's recirculation gyres. A breakdown of the eddy forcing into contributions from individual terms confirms the expected role of cross-jet gradients in meridional eddy tilt in stabilizing the jet to its barotropic instability; ho...
-
On the Deep Western Boundary Current south of Cape Cod
Deep-sea Research Part Ii-topical Studies in Oceanography, 2005Co-Authors: Terrence M. Joyce, Robert S. Pickart, Jane Dunworth-baker, Daniel J. Torres, Stephanie WatermanAbstract:Abstract Using CTD/oxygen data from eight cruises in the decade from 1994–2003, we have constructed a mean ‘section’ of properties across the Deep Western Boundary Current (DWBC) south of Cape Cod near 70°W. Since all sections included direct velocity measurements, our composite section enables us to portray the flow field as well as the mean water mass structure. Inshore of the Gulf Stream between the 2500 and 4000 m isobaths, the flow is to the southwest along the bathymetry and is remarkably barotropic. The equatorward flowing Labrador Sea Water is shown to have high dissolved oxygen, low salinity, and low potential vorticity, while the underlying Overflow Water is high in oxygen. Transport estimates for the cold limb of the thermohaline circulation give a range of −14 to −19 Sv for the N. Atlantic Deep Water found on the section. The greatest uncertainty is due to the presence of a Warm-Core Ring on one of the sections, which apparently completely reversed the flow in the DWBC. Offshore of the DWBC, some of the deep source waters are returned to the north in the deep Gulf Stream. The section is compared to two other, widely separated locations (Abaco and 55°W) that have markedly different DWBC characteristics.
Michael A. Spall - One of the best experts on this subject based on the ideXlab platform.
-
Cyclonic eddies in the West Greenland Boundary Current system
2021Co-Authors: Astrid Pacini, Robert S. Pickart, Isabela A. Le Bras, Fiammetta Straneo, N. Penny Holliday, Michael A. SpallAbstract:<p>The Labrador Sea is an important site for deep convection, and the Boundary Current surrounding the Sea impacts the strength of this convection and the subsequent restratification. As part of the Overturning of the Subpolar North Atlantic Program, ten moorings have been maintained on the West Greenland shelf and slope that provide hourly, high-resolution renderings of the Boundary Current. These data reveal the presence and propagation of abundant mid-depth intensified cyclonic eddies, which have not previously been documented in the West Greenland Boundary Current system. This study quantifies these features and their structure and demonstrates that they are the downstream manifestation of Denmark Strait Overflow Water (DSOW) cyclones. Using the mooring data, the statistics of these features are presented, a composite eddy is constructed, and the velocity and transport structure are described. A synoptic survey of the region captured two of these features, and provides further insight into their structure and timing. This is the first time DSOW cyclones have been observed in the Labrador Sea, and their presence, propagation, and transport must be accounted for in order to assess their contribution to the heat and freshwater budgets of the Labrador Sea interior.</p>
-
Nonlinear Radiating Instability of a Barotropic Eastern Boundary Current
Journal of Physical Oceanography, 2013Co-Authors: Jinbo Wang, Michael A. Spall, Glenn R. Flierl, Paola Malanotte-rizzoliAbstract:Linear and nonlinear radiating instabilities of an eastern Boundary Current are studied using a barotropic quasigeostrophic model in an idealized meridional channel. The eastern Boundary Current is meridionally uniform and produces unstable modes in which long waves are most able to radiate. These long radiating modes are easily suppressed by friction because of their small growth rates. However, the long radiating modescanovercomefrictionbynonlinear energyinputtransferredfromthemoreunstabletrappedmodeand play an important role in the energy budget of the Boundary Current system. The nonlinearly powered long radiating modes take away part of the perturbation energy from the instability origin to the ocean interior. The radiated instabilities can generate zonal striations in the ocean interior that are comparable to features observed in the ocean. Subharmonic instability is identified to be responsible for the nonlinear resonance betweentheradiatingandtrappedmodes,butmoregeneralnonlineartriadinteractionsareexpectedtoapply in a highly nonlinear environment.
-
Radiating Instability of a Meridional Boundary Current
Journal of Physical Oceanography, 2008Co-Authors: Hristina G. Hristova, Joseph Pedlosky, Michael A. SpallAbstract:Abstract A linear stability analysis of a meridional Boundary Current on the beta plane is presented. The Boundary Current is idealized as a constant-speed meridional jet adjacent to a semi-infinite motionless far field. The far-field region can be situated either on the eastern or the western side of the jet, representing a western or an eastern Boundary Current, respectively. It is found that when unstable, the meridional Boundary Current generates temporally growing propagating waves that transport energy away from the locally unstable region toward the neutral far field. This is the so-called radiating instability and is found in both barotropic and two-layer baroclinic configurations. A second but important conclusion concerns the differences in the stability properties of eastern and western Boundary Currents. An eastern Boundary Current supports a greater number of radiating modes over a wider range of meridional wavenumbers. It generates waves with amplitude envelopes that decay slowly with distan...
-
Radiating Instability of a Meridional Boundary Current
Journal of Physical Oceanography, 2008Co-Authors: Hristina G. Hristova, Joseph Pedlosky, Michael A. SpallAbstract:A linear stability analysis of a meridional Boundary Current on the beta plane is presented. The Boundary Current is idealized as a constant-speed meridional jet adjacent to a semi-infinite motionless far field. The far-field region can be situated either on the eastern or the western side of the jet, representing a western or an eastern Boundary Current, respectively. It is found that when unstable, the meridional Boundary Current generates temporally growing propagating waves that transport energy away from the locally unstable region toward the neutral far field. This is the so-called radiating instability and is found in both barotropic and two-layer baroclinic configurations. A second but important conclusion concerns the differences in the stability properties of eastern and western Boundary Currents. An eastern Boundary Current supports a greater number of radiating modes over a wider range of meridional wavenumbers. It generates waves with amplitude envelopes that decay slowly with distance from the Current. The radiating waves tend to have an asymmetrical horizontal structure—they are much longer in the zonal direction than in the meridional, a consequence of which is that unstable eastern Boundary Currents, unlike western Boundary Currents, have the potential to act as a source of zonal jets for the interior of the ocean.
-
Boundary Current Eddies and Their Role in the Restratification of the Labrador Sea
Journal of Physical Oceanography, 2004Co-Authors: Caroline A. Katsman, Michael A. Spall, Robert S. PickartAbstract:An idealized model is used to study the restratification of the Labrador Sea after deep convection, with emphasis on the role of Boundary Current eddies shed near the west coast of Greenland. The Boundary Current eddies carry warm, buoyant Irminger Current water into the Labrador Sea interior. For a realistic end-of-winter state, it is shown that these Irminger Current eddies are efficient in restratifying the convected water mass in the interior of the Labrador Sea. In addition, it is demonstrated that Irminger Current eddies can balance a significant portion of the atmospheric heat loss and thus play an important role for the watermass transformation in the Labrador Sea.
Daniel J. Torres - One of the best experts on this subject based on the ideXlab platform.
-
The Atlantic Water Boundary Current north of Svalbard in late summer
Journal of Geophysical Research: Oceans, 2017Co-Authors: M. Dolores Pérez-hernández, Robert S. Pickart, Daniel J. Torres, Vladimir Pavlov, Kjetil Våge, Randi Ingvaldsen, Arild Sundfjord, Angelika H. H. Renner, Svetlana Y. ErofeevaAbstract:Data from a shipboard hydrographic/velocity survey carried out in September 2013 of the region north of Svalbard in the Nansen Basin are analyzed to characterize the Atlantic Water (AW) Boundary Current as it flows eastward along the continental slope. Eight meridional transects across the Current, spanning an alongstream distance of 180 km, allow for a detailed description of the Current and the regional water masses. During the survey the winds were light and there was no pack-ice. The mean section reveals that the Boundary Current was O(40 km) wide, surface-intensified, with a maximum velocity of 20 cm/s. Its mean transport during the survey was 3.11 ± 0.33 Sv, of which 2.31 ± 0.29 Sv was AW. This suggests that the two branches of AW entering the Arctic Ocean via Fram Strait—the Yermak Plateau branch and the Svalbard branch—have largely combined into a single Current by 30°E. At this location the Boundary Current meanders with a systematic change in its kinematic structure during offshore excursions. A potential vorticity analysis indicates that the flow is baroclinically unstable, consistent with previous observations of AW anticyclones offshore of the Current as well as the presence of a near-field cyclone in this data set. Our survey indicates that only a small portion of the Boundary Current is diverted into the Kvitoya Trough (0.17 ± 0.08 Sv) and that the AW temperature/salinity signal is quickly eroded within the trough.
-
The Atlantic Water Boundary Current in the Nansen Basin: Transport and mechanisms of lateral exchange
Journal of Geophysical Research: Oceans, 2016Co-Authors: Kjetil Våge, Robert S. Pickart, Daniel J. Torres, Vladimir Pavlov, Randi Ingvaldsen, Arild Sundfjord, Peigen Lin, Andrey ProshutinskyAbstract:Data from a shipboard hydrographic survey near 30°E in the Nansen Basin of the Arctic Ocean are used to investigate the structure and transport of the Atlantic Water Boundary Current. Two high-resolution synoptic crossings of the Current indicate that it is roughly 30 km wide and weakly mid-depth intensified. Using a previously-determined definition of Atlantic Water, the transport of this water mass is calculated to be 1.6 ± 0.3 Sv, which is similar to the transport of Atlantic Water in the inner branch of the West Spitsbergen Current. At the time of the survey a small anti-cyclonic eddy of Atlantic Water was situated just offshore of the Boundary Current. The data suggest that the feature was recently detached from the Boundary Current, and, due to compensating effects of temperature and salinity on the thermal wind shear, the maximum swirl speed was situated below the hydrographic property core. Two other similar features were detected within our study domain, suggesting that these eddies are common and represent an effective means of fluxing warm and salty water from the Boundary Current into the interior. An atmospheric low pressure system transiting south of our study area resulted in southeasterly winds prior to and during the field measurements. A comparison to hydrographic data from the Pacific Water Boundary Current in the Canada Basin under similar atmospheric forcing suggests that upwelling was taking place during the survey. This provides a second mechanism related to cross-stream exchange of heat and salt in this region of the Nansen Basin. This article is protected by copyright. All rights reserved.
-
the western arctic Boundary Current at 152 w structure variability and transport
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Anna Nikolopoulos, Robert S. Pickart, Daniel J. Torres, Paula S Fratantoni, Koji Shimada, Peter E JonesAbstract:Abstract From August 2002 to September 2004 a high-resolution mooring array was maintained across the western Arctic Boundary Current in the Beaufort Sea north of Alaska. The array consisted of profiling instrumentation, providing a timeseries of vertical sections of the Current. Here we present the first-year velocity measurements, with emphasis on the Pacific water component of the Current. The mean flow is characterized as a bottom-intensified jet of O (15 cm s−1) directed to the east, trapped to the shelfbreak near 100 m depth. Its width scale is only 10–15 km. Seasonally the flow has distinct configurations. During summer it becomes surface-intensified as it advects buoyant Alaskan Coastal water. In fall and winter the Current often reverses (flows westward) under upwelling-favorable winds. Between the storms, as the eastward flow re-establishes, the Current develops a deep extension to depths exceeding 700 m. In spring the bottom-trapped flow advects winter-transformed Pacific water emanating from the Chukchi Sea. The year-long mean volume transport of Pacific water is 0.13±0.08 Sv to the east, which is less than 20% of the long-term mean Bering Strait inflow. This implies that most of the Pacific water entering the Arctic goes elsewhere, contrary to expected dynamics and previous modeling results. Possible reasons for this are discussed. The mean Atlantic water transport (to 800 m depth) is 0.047±0.026 Sv, also smaller than anticipated.
-
On the Deep Western Boundary Current south of Cape Cod
Deep-sea Research Part Ii-topical Studies in Oceanography, 2005Co-Authors: Terrence M. Joyce, Robert S. Pickart, Jane Dunworth-baker, Daniel J. Torres, Stephanie WatermanAbstract:Abstract Using CTD/oxygen data from eight cruises in the decade from 1994–2003, we have constructed a mean ‘section’ of properties across the Deep Western Boundary Current (DWBC) south of Cape Cod near 70°W. Since all sections included direct velocity measurements, our composite section enables us to portray the flow field as well as the mean water mass structure. Inshore of the Gulf Stream between the 2500 and 4000 m isobaths, the flow is to the southwest along the bathymetry and is remarkably barotropic. The equatorward flowing Labrador Sea Water is shown to have high dissolved oxygen, low salinity, and low potential vorticity, while the underlying Overflow Water is high in oxygen. Transport estimates for the cold limb of the thermohaline circulation give a range of −14 to −19 Sv for the N. Atlantic Deep Water found on the section. The greatest uncertainty is due to the presence of a Warm-Core Ring on one of the sections, which apparently completely reversed the flow in the DWBC. Offshore of the DWBC, some of the deep source waters are returned to the north in the deep Gulf Stream. The section is compared to two other, widely separated locations (Abaco and 55°W) that have markedly different DWBC characteristics.
Naoki Hirose - One of the best experts on this subject based on the ideXlab platform.
-
Poleward-propagating near-inertial waves enabled by the western Boundary Current
Scientific Reports, 2019Co-Authors: Chanhyung Jeon, Xiao-hua Zhu, Hong Sik Min, Sok Kuh Kang, Hanna Na, Ayako Nishina, Jae-hun Park, Hirohiko Nakamura, Dong-guk Kim, Naoki HiroseAbstract:Near-inertial waves (NIWs), which have clockwise (anticlockwise) rotational motion in the Northern (Southern) Hemisphere, exist everywhere in the ocean except at the equator; their frequencies are largely determined by the local inertial frequency, f. It is thought that they supply about 25% of the energy for global ocean mixing through turbulence resulting from their strong Current shear and breaking; this contributes mainly to upper-ocean mixing which is related to air-sea interaction, typhoon genesis, marine ecosystem, carbon cycle, and climate change. Observations and numerical simulations have shown that the low-mode NIWs can travel many hundreds of kilometres from a source region toward the equator because the lower inertial frequency at lower latitudes allows their free propagation. Here, using observations and a numerical simulation, we demonstrate poleward propagation of typhoon-induced NIWs by a western Boundary Current, the Kuroshio. Negative relative vorticity, meaning anticyclonic rotational tendency opposite to the Earth’s spin, existing along the right-hand side of the Kuroshio path, makes the local inertial frequency shift to a lower value, thereby trapping the waves. This negative vorticity region works like a waveguide for NIW propagation, and the strong Kuroshio Current advects the waves poleward with a speed ~85% of the local Current. This finding emphasizes that background Currents such as the Kuroshio and the Gulf Stream play a significant role in redistribution of the NIW energy available for global ocean mixing.