We investigate the effect of wave-eddy interaction and dissipation of internal gravity waves propagating in a coherent meso-scale eddy simulated using a novel numerical model called the Internal Wave Energy Model based on the six-dimensional radiative transfer equation. We use an idealized mean flow structure and stratification, motivated by observations of a coherent eddy in the Canary Current System. In a spin-down simulation using the Garret-Munk model spectrum as initial conditions, we find that wave energy decreases at the eddy rim. Lateral shear leads to wave energy gain due to a developing horizontal anisotropy outside the eddy and at the rim, while vertical shear leads to wave energy loss which is enhanced at the eddy rim. Wave energy loss by wave dissipation due to vertical shear dominates over horizontal shear. Our results show similar behaviour of the internal gravity wave in a cyclonic as well as an anticyclonic eddy. Wave dissipation by vertical wave refraction occurs predominantly at the eddy rim near the surface, where related vertical diffusivities range from 𝒪(10−7) to 𝒪(10−5)m2s−1.
{"title":"Evolution of internal gravity waves in a meso-scale eddy simulated using a novel model","authors":"Pablo Sebastia Saez, Carsten Eden, M. Chouksey","doi":"10.1175/jpo-d-23-0095.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0095.1","url":null,"abstract":"\u0000We investigate the effect of wave-eddy interaction and dissipation of internal gravity waves propagating in a coherent meso-scale eddy simulated using a novel numerical model called the Internal Wave Energy Model based on the six-dimensional radiative transfer equation. We use an idealized mean flow structure and stratification, motivated by observations of a coherent eddy in the Canary Current System. In a spin-down simulation using the Garret-Munk model spectrum as initial conditions, we find that wave energy decreases at the eddy rim. Lateral shear leads to wave energy gain due to a developing horizontal anisotropy outside the eddy and at the rim, while vertical shear leads to wave energy loss which is enhanced at the eddy rim. Wave energy loss by wave dissipation due to vertical shear dominates over horizontal shear. Our results show similar behaviour of the internal gravity wave in a cyclonic as well as an anticyclonic eddy. Wave dissipation by vertical wave refraction occurs predominantly at the eddy rim near the surface, where related vertical diffusivities range from 𝒪(10−7) to 𝒪(10−5)m2s−1.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139604818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maya I. Jakes, H. E. Phillips, Annie Foppert, A. Cyriac, N. Bindoff, S. Rintoul, Andrew F. Thompson
Eddy stirring at mesoscale oceanic fronts generates finescale filaments, visible in submesoscale-resolving model simulations and high-resolution satellite images of sea surface temperature, ocean colour and sea ice. Submesoscale filaments have widths of О(1-10 km) and evolve on timescales of hours to days, making them extremely challenging to observe. Despite their relatively small scale, submesoscale processes play a key role in the climate system by providing a route to dissipation; altering the stratification of the ocean interior; and generating strong vertical velocities that exchange heat, carbon, nutrients, and oxygen between the mixed layer and the ocean interior. We present a unique set of in-situ and satellite observations in a standing meander region of the Antarctic Circumpolar Current (ACC) that supports the theory of cold filamentary intensification -– revealing enhanced vertical velocities and evidence of subduction and ventilation associated with finescale cold filaments. We show that these processes are not confined to the mixed layer; EM-APEX floats reveal enhanced downward velocities (>100 m day−1) and evidence of ageostrophic motion extending as deep as 1600 dbar, associated with a ~20 km wide cold filament. A finer-scale (~5 km wide) cold filament crossed by a towed Triaxus is associated with anomalous chlorophyll and oxygen values extending at least 100-200 dbar below the base of the mixed layer, implying recent subduction and ventilation. Energetic standing meanders within the weakly-stratified ACC provide an environment conductive to the generation of finescale filaments that can transport water mass properties across mesoscale fronts and deep into the ocean interior.
{"title":"Observational evidence of cold filamentary intensification in an energetic meander of the Antarctic Circumpolar Current","authors":"Maya I. Jakes, H. E. Phillips, Annie Foppert, A. Cyriac, N. Bindoff, S. Rintoul, Andrew F. Thompson","doi":"10.1175/jpo-d-23-0085.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0085.1","url":null,"abstract":"\u0000Eddy stirring at mesoscale oceanic fronts generates finescale filaments, visible in submesoscale-resolving model simulations and high-resolution satellite images of sea surface temperature, ocean colour and sea ice. Submesoscale filaments have widths of О(1-10 km) and evolve on timescales of hours to days, making them extremely challenging to observe. Despite their relatively small scale, submesoscale processes play a key role in the climate system by providing a route to dissipation; altering the stratification of the ocean interior; and generating strong vertical velocities that exchange heat, carbon, nutrients, and oxygen between the mixed layer and the ocean interior. We present a unique set of in-situ and satellite observations in a standing meander region of the Antarctic Circumpolar Current (ACC) that supports the theory of cold filamentary intensification -– revealing enhanced vertical velocities and evidence of subduction and ventilation associated with finescale cold filaments. We show that these processes are not confined to the mixed layer; EM-APEX floats reveal enhanced downward velocities (>100 m day−1) and evidence of ageostrophic motion extending as deep as 1600 dbar, associated with a ~20 km wide cold filament. A finer-scale (~5 km wide) cold filament crossed by a towed Triaxus is associated with anomalous chlorophyll and oxygen values extending at least 100-200 dbar below the base of the mixed layer, implying recent subduction and ventilation. Energetic standing meanders within the weakly-stratified ACC provide an environment conductive to the generation of finescale filaments that can transport water mass properties across mesoscale fronts and deep into the ocean interior.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139607759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Precipitation plays a crucial role in modulating upper ocean salinity and the formation of barrier layer, which affects the development of tropical cyclones (TCs). This study performed idealized simulations to investigate the influence of precipitation on the upper ocean. Precipitation acts to suppress the wind-induced sea surface reduction and generates an asymmetric warming response with a rightward-bias. There is substantial vertical change with a cooling anomaly in the subsurface, which is about three times larger than the surface warming. The mean tropical cyclone heat potential is locally increased but the net effect across the cyclone footprint is small. The impact of precipitation on the ocean tends to saturate for extreme precipitation, suggesting a non-linear feedback. A prevailing driver of the model behavior is that the freshwater flux from precipitation strengthens the stratification and increases current shear in the upper ocean, trapping more kinetic energy in the surface layer and subsequently weakening near-inertial waves in the deep ocean. This study highlights the competing role of TC precipitation and wind. For TC is weaker than Category 3, the warming anomaly is caused by reduced vertical mixing, whereas for stronger TCs, the advection process is most important.
{"title":"Impact of Precipitation on Ocean Responses during Tropical Cyclone","authors":"Fu Liu, Ralf Toumi, Han Zhang, Dake Chen","doi":"10.1175/jpo-d-23-0138.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0138.1","url":null,"abstract":"\u0000Precipitation plays a crucial role in modulating upper ocean salinity and the formation of barrier layer, which affects the development of tropical cyclones (TCs). This study performed idealized simulations to investigate the influence of precipitation on the upper ocean. Precipitation acts to suppress the wind-induced sea surface reduction and generates an asymmetric warming response with a rightward-bias. There is substantial vertical change with a cooling anomaly in the subsurface, which is about three times larger than the surface warming. The mean tropical cyclone heat potential is locally increased but the net effect across the cyclone footprint is small. The impact of precipitation on the ocean tends to saturate for extreme precipitation, suggesting a non-linear feedback. A prevailing driver of the model behavior is that the freshwater flux from precipitation strengthens the stratification and increases current shear in the upper ocean, trapping more kinetic energy in the surface layer and subsequently weakening near-inertial waves in the deep ocean. This study highlights the competing role of TC precipitation and wind. For TC is weaker than Category 3, the warming anomaly is caused by reduced vertical mixing, whereas for stronger TCs, the advection process is most important.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139612251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite the large radius (R17) of gale-force wind of a tropical cyclone (TC), the observed TC-induced effects on mesoscale and large-scale ocean via the baroclinic geostrophic response are found to have a limited cross-track width; this strange but important phenomenon is interpreted here. Driven by the wind stress curl (WSC), the TC-induced geostrophic response is in fact regulated by along-track integration of the WSC (AIWSC). Constrained by atmospheric TC dynamics, the violent winds outside the radius (Rmax) of maximum wind of any TC must have nearly zero WSC. Consequently, the AIWSC function can be fit as a boxcar function with an extraordinarily large positive value between ±Rmax about the track. Based on this boxcar function, the theoretical estimate of the cross-track length scale of the baroclinic geostrophic response, Ld + Rmax, is presented, where Ld is the first-mode baroclinic Rossby deformation radius. Further, this scale is validated by numerical experiments to well explain the width of the altimetry-observed geostrophic response induced by any TC. Evidently, Ld + Rmax is far smaller than R17 and thus the baroclinic geostrophic response generally have a limited width. This study implies that, although for a TC the violent winds outside Rmax are generally ∼90% of all winds, in an open ocean these winds may be useless to perturb the ocean interior due to the nearly zero WSC.
{"title":"Limited width of tropical cyclone-induced baroclinic geostrophic response","authors":"Zhumin Lu, Xiaodong Shang","doi":"10.1175/jpo-d-23-0096.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0096.1","url":null,"abstract":"\u0000Despite the large radius (R17) of gale-force wind of a tropical cyclone (TC), the observed TC-induced effects on mesoscale and large-scale ocean via the baroclinic geostrophic response are found to have a limited cross-track width; this strange but important phenomenon is interpreted here. Driven by the wind stress curl (WSC), the TC-induced geostrophic response is in fact regulated by along-track integration of the WSC (AIWSC). Constrained by atmospheric TC dynamics, the violent winds outside the radius (Rmax) of maximum wind of any TC must have nearly zero WSC. Consequently, the AIWSC function can be fit as a boxcar function with an extraordinarily large positive value between ±Rmax about the track. Based on this boxcar function, the theoretical estimate of the cross-track length scale of the baroclinic geostrophic response, Ld + Rmax, is presented, where Ld is the first-mode baroclinic Rossby deformation radius. Further, this scale is validated by numerical experiments to well explain the width of the altimetry-observed geostrophic response induced by any TC. Evidently, Ld + Rmax is far smaller than R17 and thus the baroclinic geostrophic response generally have a limited width. This study implies that, although for a TC the violent winds outside Rmax are generally ∼90% of all winds, in an open ocean these winds may be useless to perturb the ocean interior due to the nearly zero WSC.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139525838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two recently proposed mixing diagnostics are employed to estimate the global surface irreversible mixing based on particle and tracer simulation driven by satellite-derived geostrophic velocities. These two novel diagnostics, similar to the traditional dispersion diffusivity and Nakamura’s effective diffusivity but defined in a localized and instantaneous sense, have the following advantages: 1) reconcile the theoretical discrepancies between Eulerian-, particle-, and contour-based diffusivities; 2) do not rely on the stationary and homogeneous assumptions of the turbulent ocean and are free from traditional average operators (e.g., Eulerian time-/space or along-contour mean). Our results show that evident discrepancies among these three types of diffusivities do emerge when employing traditional estimates. However, these discrepancies could be significantly mitigated with the adoption of new diagnostic methods, implying that the three types of diffusivities can be effectively reconciled within a global framework. Moreover, finescale mixing structures and transient elevated mixing events due to geostrophic stirring can be clearly identified by the two new diagnostics, in contrast to previous estimates that are spatially and/or temporally smoothed. In particular, it is interesting to note that large values of the new diagnostics usually occur along narrow filaments/fronts associated with mesoscale eddies, and elevated mixing is observed to be located at the periphery of eddies. Our study presents a novel revisit of the global surface mixing induced by geostrophic eddies with an emphasis on irreversibility, and provides new insights into previous questions regarding to different mixing diagnostics in the community.
{"title":"Irreversible mixing induced by geostrophic turbulence over the global ocean","authors":"Tongya Liu, Yu‐Kun Qian, Xiaohui Liu, Shiqiu Peng, Dake Chen","doi":"10.1175/jpo-d-23-0071.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0071.1","url":null,"abstract":"\u0000Two recently proposed mixing diagnostics are employed to estimate the global surface irreversible mixing based on particle and tracer simulation driven by satellite-derived geostrophic velocities. These two novel diagnostics, similar to the traditional dispersion diffusivity and Nakamura’s effective diffusivity but defined in a localized and instantaneous sense, have the following advantages: 1) reconcile the theoretical discrepancies between Eulerian-, particle-, and contour-based diffusivities; 2) do not rely on the stationary and homogeneous assumptions of the turbulent ocean and are free from traditional average operators (e.g., Eulerian time-/space or along-contour mean). Our results show that evident discrepancies among these three types of diffusivities do emerge when employing traditional estimates. However, these discrepancies could be significantly mitigated with the adoption of new diagnostic methods, implying that the three types of diffusivities can be effectively reconciled within a global framework. Moreover, finescale mixing structures and transient elevated mixing events due to geostrophic stirring can be clearly identified by the two new diagnostics, in contrast to previous estimates that are spatially and/or temporally smoothed. In particular, it is interesting to note that large values of the new diagnostics usually occur along narrow filaments/fronts associated with mesoscale eddies, and elevated mixing is observed to be located at the periphery of eddies. Our study presents a novel revisit of the global surface mixing induced by geostrophic eddies with an emphasis on irreversibility, and provides new insights into previous questions regarding to different mixing diagnostics in the community.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139525053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ian A. Stokes, Samuel M. Kelly, Andrew J. Lucas, A. Waterhouse, Caitlin B. Whalen, T. Klenz, Verena Hormann, Luca Centurioni
We construct a generalized slab model to calculate the ocean’s linear response to an arbitrary, depth-variable forcing stress profile. To introduce a first-order improvement to the linear stress profile of the traditional slab model, a nonlinear stress profile which allows momentum to penetrate into the transition layer (TL) is used (denoted ‘mixed layer/transition layer,’ or MLTL stress profile). The MLTL stress profile induces a two-fold reduction in power input to inertial motions relative to the traditional slab approximation. The primary reduction arises as the TL allows momentum to be deposited over a greater depth range, reducing surface currents. The secondary reduction results from the production of turbulent kinetic energy (TKE) beneath the mixed layer (ML) related to interactions between shear stress and velocity shear. Direct comparison between observations in the Iceland Basin, the traditional slab model, the generalized slab model with the MLTL stress profile, and the Price-Weller-Pinkel (PWP) model suggest that the generalized slab model offers improved performance over a traditional slab model. In the Iceland Basin, modeled TKE production in the TL is consistent with observations of turbulent dissipation. Extension to global results via analysis of Argo profiling float data suggests that on the global, annual-mean, ∼ 30% of the total power input to near-inertial motions is allocated to TKE production. We apply this result to the latest global, annual-mean estimates for near-inertial power input (0.27 TW) to estimate that 0.08 ± 0.01 TW of the total near-inertial power input are diverted to TKE production.
{"title":"A generalized slab model","authors":"Ian A. Stokes, Samuel M. Kelly, Andrew J. Lucas, A. Waterhouse, Caitlin B. Whalen, T. Klenz, Verena Hormann, Luca Centurioni","doi":"10.1175/jpo-d-23-0167.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0167.1","url":null,"abstract":"\u0000We construct a generalized slab model to calculate the ocean’s linear response to an arbitrary, depth-variable forcing stress profile. To introduce a first-order improvement to the linear stress profile of the traditional slab model, a nonlinear stress profile which allows momentum to penetrate into the transition layer (TL) is used (denoted ‘mixed layer/transition layer,’ or MLTL stress profile). The MLTL stress profile induces a two-fold reduction in power input to inertial motions relative to the traditional slab approximation. The primary reduction arises as the TL allows momentum to be deposited over a greater depth range, reducing surface currents. The secondary reduction results from the production of turbulent kinetic energy (TKE) beneath the mixed layer (ML) related to interactions between shear stress and velocity shear. Direct comparison between observations in the Iceland Basin, the traditional slab model, the generalized slab model with the MLTL stress profile, and the Price-Weller-Pinkel (PWP) model suggest that the generalized slab model offers improved performance over a traditional slab model. In the Iceland Basin, modeled TKE production in the TL is consistent with observations of turbulent dissipation. Extension to global results via analysis of Argo profiling float data suggests that on the global, annual-mean, ∼ 30% of the total power input to near-inertial motions is allocated to TKE production. We apply this result to the latest global, annual-mean estimates for near-inertial power input (0.27 TW) to estimate that 0.08 ± 0.01 TW of the total near-inertial power input are diverted to TKE production.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139617254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alejandra Sanchez-Rios, R. K. Shearman, Craig M. Lee, H. Simmons, Louis St. Laurent, Andrew J. Lucas, T. Ijichi, Sen Jan
The Kuroshio occasionally carries warm and salty North Pacific Water into fresher waters of the South China Sea, forming a front with a complex temperature-salinity (T-S) structure to the west of the Luzon Strait. In this study, we examine the T-S interleavings formed by alternating layers of North Pacific water with South China Sea water in a front formed during the winter monsoon season of 2014. Using observations from a glider array following a free-floating wave-powered vertical profiling float to calculate the fine-scale parameters Turner angle, Tu, and Richardson number, Ri, we identified areas favorable to double diffusion convection and shear instability observed in a T-S interleaving. We evaluated the contribution of double diffusion convection and shear instabilities to the thermal variance diffusivity, X, using microstructure data and compared it with previous parameterization schemes based on fine-scale properties. We discover that turbulent mixing is not accurately parameterized when both Tu and Ri are within critical ranges (Tu > 60, Ri < 1/4). In particular, X associated with salt finger processes was an order of magnitude higher (6.7×10−7 K2 s−1) than in regions where only velocity shear was likely to drive mixing (8.7×10−8 K2 s−1).
黑潮偶尔会将温暖而含盐的北太平洋海水带入较新鲜的南海海水中，在吕宋海峡以西形成具有复杂温度-盐度（T-S）结构的锋面。在本研究中，我们考察了 2014 年冬季季风季节形成的锋面中北太平洋水层与南海水层交替形成的 T-S 交错结构。利用滑翔机阵列跟随自由浮动的波动力垂直剖面浮筒进行观测，计算细尺度参数特纳角（Tu）和理查森数（Ri），我们确定了在 T-S 交错中观测到的有利于双重扩散对流和剪切不稳定性的区域。我们利用微结构数据评估了双重扩散对流和剪切不稳定性对热变异扩散率 X 的贡献，并将其与之前基于细尺度特性的参数化方案进行了比较。我们发现，当 Tu 和 Ri 都在临界范围内（Tu > 60，Ri < 1/4）时，湍流混合的参数化并不准确。特别是，与盐指过程相关的 X 值（6.7×10-7 K2 s-1）比在只有速度剪切可能驱动混合的区域（8.7×10-8 K2 s-1）高出一个数量级。
{"title":"Characterization of mixing at the edge of a Kuroshio intrusion into the South China Sea: analysis of thermal variance diffusivity measurements","authors":"Alejandra Sanchez-Rios, R. K. Shearman, Craig M. Lee, H. Simmons, Louis St. Laurent, Andrew J. Lucas, T. Ijichi, Sen Jan","doi":"10.1175/jpo-d-23-0007.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0007.1","url":null,"abstract":"\u0000The Kuroshio occasionally carries warm and salty North Pacific Water into fresher waters of the South China Sea, forming a front with a complex temperature-salinity (T-S) structure to the west of the Luzon Strait. In this study, we examine the T-S interleavings formed by alternating layers of North Pacific water with South China Sea water in a front formed during the winter monsoon season of 2014. Using observations from a glider array following a free-floating wave-powered vertical profiling float to calculate the fine-scale parameters Turner angle, Tu, and Richardson number, Ri, we identified areas favorable to double diffusion convection and shear instability observed in a T-S interleaving. We evaluated the contribution of double diffusion convection and shear instabilities to the thermal variance diffusivity, X, using microstructure data and compared it with previous parameterization schemes based on fine-scale properties. We discover that turbulent mixing is not accurately parameterized when both Tu and Ri are within critical ranges (Tu > 60, Ri < 1/4). In particular, X associated with salt finger processes was an order of magnitude higher (6.7×10−7 K2 s−1) than in regions where only velocity shear was likely to drive mixing (8.7×10−8 K2 s−1).","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139622003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Delpech, R. Barkan, K. Srinivasan, J. McWilliams, B. Arbic, Oladeji Q. Siyanbola, M. Buijsman
Oceanic mixing, mostly driven by the breaking of internal waves at small scales in the ocean interior, is of major importance for ocean circulation and the ocean response to future climate scenarios. Understanding how internal waves transfer their energy to smaller scales from their generation to their dissipation is therefore an important step for improving the representation of ocean mixing in climate models. In this study, the processes leading to cross-scale energy fluxes in the internal wave field are quantified using an original decomposition approach in a realistic numerical simulation of the California Current. We quantify the relative contribution of eddy-internal wave interactions and wave-wave interactions to these fluxes and show that eddy-internal wave interactions are more efficient than wave-wave interactions in the formation of the internal wave continuum spectrum. Carrying out twin numerical simulations, where we successively activate or deactivate one of the main internal wave forcing, we also show that eddy - near-inertial internal wave interactions are more efficient in the cross-scale energy transfer than eddy - tidal internal wave interactions. This results in the dissipation being dominated by the near-inertial internal waves over tidal internal waves. A companion study focuses on the role of stimulated cascade on the energy and enstrophy fluxes.
{"title":"Eddy - Internal Wave Interactions and their Contribution to Cross-Scale Energy Fluxes: a case study in the California Current","authors":"A. Delpech, R. Barkan, K. Srinivasan, J. McWilliams, B. Arbic, Oladeji Q. Siyanbola, M. Buijsman","doi":"10.1175/jpo-d-23-0181.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0181.1","url":null,"abstract":"\u0000Oceanic mixing, mostly driven by the breaking of internal waves at small scales in the ocean interior, is of major importance for ocean circulation and the ocean response to future climate scenarios. Understanding how internal waves transfer their energy to smaller scales from their generation to their dissipation is therefore an important step for improving the representation of ocean mixing in climate models. In this study, the processes leading to cross-scale energy fluxes in the internal wave field are quantified using an original decomposition approach in a realistic numerical simulation of the California Current. We quantify the relative contribution of eddy-internal wave interactions and wave-wave interactions to these fluxes and show that eddy-internal wave interactions are more efficient than wave-wave interactions in the formation of the internal wave continuum spectrum. Carrying out twin numerical simulations, where we successively activate or deactivate one of the main internal wave forcing, we also show that eddy - near-inertial internal wave interactions are more efficient in the cross-scale energy transfer than eddy - tidal internal wave interactions. This results in the dissipation being dominated by the near-inertial internal waves over tidal internal waves. A companion study focuses on the role of stimulated cascade on the energy and enstrophy fluxes.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139529586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamics of typhoon-induced waves in semi-enclosed seas become an interesting topic with the increase of the typhoon intensity. Based on the calibrated Simulating Waves Nearshore (SWAN) model, wave dynamics were investigated under distinct typhoon tracks (e.g., Matmo (2014), Rumbia (2018), and Lekima (2019)) in the Bohai Sea. Distributions of significant wave heights (SWHs) are affected by the typhoon wind fields and are directly related to the typhoon tracks. The classical JONSWAP wave spectra were adopted for the analysis of sea states (e.g., wind-seas or swells) to further explain variations in wave heights. Results indicate that the dominant sea state with higher energy experiences significant spatiotemporal variability under distinct tracks. For typhoons passing through the central part of the Bohai Sea (e.g., Rumbia), high-energy waves are observed under swell-dominated and mixed sea states, which are subjected to the fetch limitation in the semi-enclosed sea and rapid changes in typhoon winds. The high energy waves induced by other typhoons passing along the edges of the Bohai Sea correspond to the wind-sea dominated sea state. Spatiotemporal variability of the sea state exhibits a high correlation with its position relative to the typhoon center. Therefore, a reference frame based on the radius of the maximum wind speed was established to discuss the sea states in this semi-enclosed sea. Further investigations reveal that swells (wind-seas) dominate the regions within the radius of the maximum wind speed (elsewhere), and the double-peaked wave spectra tend to appear in the left quadrants.
{"title":"Wave spectra analysis on the spatiotemporal variability of sea states under distinct typhoon tracks in a semi-enclosed sea","authors":"Jie Peng, Miaohua Mao, Meng Xia","doi":"10.1175/jpo-d-23-0066.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0066.1","url":null,"abstract":"\u0000The dynamics of typhoon-induced waves in semi-enclosed seas become an interesting topic with the increase of the typhoon intensity. Based on the calibrated Simulating Waves Nearshore (SWAN) model, wave dynamics were investigated under distinct typhoon tracks (e.g., Matmo (2014), Rumbia (2018), and Lekima (2019)) in the Bohai Sea. Distributions of significant wave heights (SWHs) are affected by the typhoon wind fields and are directly related to the typhoon tracks. The classical JONSWAP wave spectra were adopted for the analysis of sea states (e.g., wind-seas or swells) to further explain variations in wave heights. Results indicate that the dominant sea state with higher energy experiences significant spatiotemporal variability under distinct tracks. For typhoons passing through the central part of the Bohai Sea (e.g., Rumbia), high-energy waves are observed under swell-dominated and mixed sea states, which are subjected to the fetch limitation in the semi-enclosed sea and rapid changes in typhoon winds. The high energy waves induced by other typhoons passing along the edges of the Bohai Sea correspond to the wind-sea dominated sea state. Spatiotemporal variability of the sea state exhibits a high correlation with its position relative to the typhoon center. Therefore, a reference frame based on the radius of the maximum wind speed was established to discuss the sea states in this semi-enclosed sea. Further investigations reveal that swells (wind-seas) dominate the regions within the radius of the maximum wind speed (elsewhere), and the double-peaked wave spectra tend to appear in the left quadrants.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139622931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paul A. Sanders, Martijn D. Dorrestijn, Theo Gerkema
The along-slope propagation of sub-inertial trapped internal tides is studied for the configuration of a simple step. It is revealed that they form a beam structure in the along-slope direction that is evanescent above the top of the step; these beams lack strict periodicity in the along-slope direction. As in classical internal Kelvin waves, they become less sharp away from the step, as higher modes decay more rapidly in the cross-slope direction. We discuss implications for abyssal mixing and outline the necessary ingredients for their generation.
{"title":"Note on the beam structure in step-trapped internal tides","authors":"Paul A. Sanders, Martijn D. Dorrestijn, Theo Gerkema","doi":"10.1175/jpo-d-23-0084.1","DOIUrl":"https://doi.org/10.1175/jpo-d-23-0084.1","url":null,"abstract":"\u0000The along-slope propagation of sub-inertial trapped internal tides is studied for the configuration of a simple step. It is revealed that they form a beam structure in the along-slope direction that is evanescent above the top of the step; these beams lack strict periodicity in the along-slope direction. As in classical internal Kelvin waves, they become less sharp away from the step, as higher modes decay more rapidly in the cross-slope direction. We discuss implications for abyssal mixing and outline the necessary ingredients for their generation.","PeriodicalId":56115,"journal":{"name":"Journal of Physical Oceanography","volume":null,"pages":null},"PeriodicalIF":3.5,"publicationDate":"2024-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139529231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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