Journal of Geophysical Research-Oceans最新文献

{"title":"Long-Term Variability of Phytoplankton Primary Production in the Ulleung Basin, East Sea/Japan Sea Using Ocean Color Remote Sensing","authors":"Dabin Lee,&nbsp;Dong-Hun Lee,&nbsp;Huitae Joo,&nbsp;Hyo Keun Jang,&nbsp;Sanghoon Park,&nbsp;Yejin Kim,&nbsp;Sungjun Kim,&nbsp;Jaesoon Kim,&nbsp;Myeongseop Kim,&nbsp;Jae-Il Kwon,&nbsp;Sang Heon Lee","doi":"10.1029/2024JC020898","DOIUrl":"https://doi.org/10.1029/2024JC020898","url":null,"abstract":"<p>In recent years, significant changes in environmental conditions and marine ecosystems have been observed in the East Sea/Japan Sea. This study investigates the long-term environmental dynamics and phytoplankton responses in the Ulleung Basin, situated in the southwestern East Sea/Japan Sea, utilizing satellite and in situ data from 2002 to 2021. Over this period, there was a noticeable increase in sea surface temperature (SST) (<i>r</i> = 0.5739, <i>p</i> &lt; 0.01), accompanied by decreasing mixed layer depth (MLD) and chlorophyll-a (Chl-a) concentration (<i>r</i> = −0.6193 and −0.6721, respectively; <i>p</i> &lt; 0.01). Nutrient concentrations within the upper 50 m significantly declined for nitrate and phosphate. A reduction in the N:P ratio indicated a shift from phosphorus-limited to nitrogen-limited environment. Moreover, primary production (PP) demonstrated a decreasing trend (<i>r</i> = −0.5840, <i>p</i> &lt; 0.01), coinciding with an increase in small phytoplankton contribution (<i>r</i> = 0.6399, <i>p</i> &lt; 0.01). Rising SST potentially altered the water column's vertical structure, hindering nutrient entrainment from the deep ocean. Consequently, this nutrient limitation may increase small phytoplankton contribution, resulting in a decline in total PP. Under the IPCC's SSP5-8.5 scenario, small phytoplankton contribution in the Ulleung Basin is projected to rise by over 10%, resulting in a 29% average PP decrease by 2100. This suggests a diminishing energy supply to the food web in a warming ocean, impacting higher trophic levels and major fishery resources. These findings emphasize the critical need for understanding and monitoring these environmental shifts for effective fisheries management and marine ecosystem conservation.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC020898","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Review of the Oceanography and Antarctic Bottom Water Formation Offshore Cape Darnley, East Antarctica","authors":"Sienna N. Blanckensee,&nbsp;David E. Gwyther,&nbsp;Ben K. Galton-Fenzi,&nbsp;Kathryn L. Gunn,&nbsp;Laura Herraiz-Borreguero,&nbsp;Kay I. Ohshima,&nbsp;Esther Portela,&nbsp;Alexandra L. Post,&nbsp;Helen C. Bostock","doi":"10.1029/2024JC021251","DOIUrl":"https://doi.org/10.1029/2024JC021251","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Antarctic Bottom Water (AABW) is the densest water mass in the world and drives the lower limb of the global thermohaline circulation. AABW is formed in only four regions around Antarctica and Cape Darnley, East Antarctica, is the most recently discovered formation region. Here, we compile 40 years of oceanographic data for this region to provide the climatological oceanographic conditions, and review the water mass properties and their role in AABW formation. We split the region into three sectors (East, Central and West) and identify the main water masses, current regimes and their influence on the formation of Cape Darnley Bottom Water (CDBW). In the eastern sector, Prydz Bay, the formation of Ice Shelf Water preconditions the water (cold and fresh) that flows into the central sector to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>68.5</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${sim} 68.5{}^{circ}$</annotation>\u0000 </semantics></math>E, enhancing sea ice production in Cape Darnley Polynya. This produces a high salinity variant of Dense Shelf Water (DSW) (up to 35.15 g/kg) that we coin Burton Basin DSW. In contrast, the western sector of the Cape Darnley Polynya produces a low salinity variant (up to 34.85 g/kg) we coin Nielsen Basin DSW. The resultant combined CDBW is the warmest (upper temperature bound of 0.05<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${}^{circ}$</annotation>\u0000 </semantics></math>C) AABW formed around Antarctica with an upper bound salinity of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>34.845 g/kg. Our findings will contribute to planning future observing systems at Cape Darnley, determining the role that CDBW plays in our global oceanic and climate systems, and modeling past and future climate scenarios.</p>\u0000 </section>\u0000 </div>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525049","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}

{"title":"GRACE Satellite Observations of Antarctic Bottom Water Transport Variability","authors":"Jemma Jeffree,&nbsp;Andrew McC. Hogg,&nbsp;Adele K. Morrison,&nbsp;Aviv Solodoch,&nbsp;Andrew L. Stewart,&nbsp;Rebecca McGirr","doi":"10.1029/2024JC020990","DOIUrl":"https://doi.org/10.1029/2024JC020990","url":null,"abstract":"<p>Antarctic Bottom Water (AABW) formation and transport constitute a key component of the global ocean circulation. Direct observations suggest that AABW volumes and transport rates may be decreasing, but these observations are too temporally or spatially sparse to determine the cause. To address this problem, we develop a new method to reconstruct AABW transport variability using data from the GRACE (Gravity Recovery and Climate Experiment) satellite mission. We use an ocean general circulation model to investigate the relationship between ocean bottom pressure and AABW: we calculate both of these quantities in the model, and link them using a regularized linear regression. Our reconstruction from modeled ocean bottom pressure can capture 65%–90% of modeled AABW transport variability, depending on the ocean basin. When realistic observational uncertainty values are added to the modeled ocean bottom pressure, the reconstruction can still capture 30%–80% of AABW transport variability. Using the same regression values, the reconstruction skill is within the same range in a second, independent, general circulation model. We conclude that our reconstruction method is not unique to the model in which it was developed and can be applied to GRACE satellite observations of ocean bottom pressure. These advances allow us to create the first global reconstruction of AABW transport variability over the satellite era. Our reconstruction provides information on the interannual variability of AABW transport, but more accurate observations are needed to discern AABW transport trends.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525048","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}

{"title":"The Observed Spatiotemporal Variability of Antarctic Winter Water","authors":"T. Spira,&nbsp;S. Swart,&nbsp;I. Giddy,&nbsp;M. du Plessis","doi":"10.1029/2024JC021017","DOIUrl":"https://doi.org/10.1029/2024JC021017","url":null,"abstract":"<p>The Southern Ocean (SO) is central to the global overturning circulation. South of the Antarctic Polar Front, Antarctic Winter Water (WW) forms in the wintertime mixed layer (ML) and becomes a subsurface layer following summertime restratification of the ML, overlaying upwelled deep waters. Model simulations show that WW acts as a conduit to seasonally transform upwelled deep waters into intermediate waters. Yet, there remains little observational evidence of the distribution and seasonal characteristics of WW. Using 18 years of in situ observations, we show seasonal climatologies of WW thickness, depth, core temperature, and salinity, revealing a distinct regionality and seasonality of WW. The seasonal cycle of WW characteristics is tied to the annual sea ice evolution, whereas the spatial distribution is impacted by the main topographic features in the SO driving an equatorward flux of WW. Through the identification of these localized northward export regions of WW, this study provides further evidence suggesting an alternative view from the conventional “zonal mean” perspective of the overturning circulation. We show that specific overturning pathways connecting the subpolar ocean to the global ocean can be explained by ocean-topography interactions.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021017","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertical Structure and Seasonal Variability of Chlorophyll Concentrations in the Southern Tropical Indian Ocean Revealed by Biogeochemical Argo Data","authors":"Xueying Ma,&nbsp;Gengxin Chen,&nbsp;Xiaoqing Chu,&nbsp;Peng Xiu","doi":"10.1029/2024JC021130","DOIUrl":"https://doi.org/10.1029/2024JC021130","url":null,"abstract":"<p>The variability of chlorophyll (Chla) in the Southern Tropical Indian Ocean (STIO) is not fully understood. This study utilized biogeochemical Argo (BGC-Argo) and satellite observations to investigate the seasonal Chla variations in the upper layer (above 200 m) and their relationships to physical dynamics. The results indicate the existence of a well-developed deep Chla maximum (DCM) layer situated between depths of 50 and 150 m. The shallowest DCM was at the Seychelles-Chagos thermocline ridge because of permanent upwelling. Both the northern (4°S–12°S, 52°E−92°E) and southern (12°S–25°S, 52°E−92°E) regions experience surface blooms during July–August. However, they exhibit distinct Chla changes in response to different physical processes and nitrate concentrations below the mixed layer. In the northern region, the thermocline plays a critical role in regulating DCM depth and intensity. From April to June, subsurface upwelling and near-surface stratification processes promote nutrient and Chla accumulation in the subsurface layer, resulting in elevated surface Chla levels in the subsequent months. In contrast, the southern region is characterized by oligotrophic conditions, where light availability primarily governs Chla variability below the mixed layer. Specifically, from November to January, when light intensity intensifies, Chla increases below the mixed layer. Furthermore, BGC-Argo data revealed a long-lived cyclonic eddy that facilitated the westward transport of Chla, significantly contributing to surface Chla blooms through eddy-pumping and eddy-trapping mechanisms. This research elucidates the fundamental characteristics of Chla distribution from a three-dimensional perspective and furthers our understanding of the complex biophysical interactions within the STIO.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525077","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}

{"title":"Impacts of the Thermocline Feedback Uncertainty on El Niño Simulations in the Tropical Pacific","authors":"Tiaoye Li,&nbsp;Lingjiang Tao,&nbsp;Rong-Hua Zhang","doi":"10.1029/2024JC021384","DOIUrl":"https://doi.org/10.1029/2024JC021384","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>As a key dynamic element of the Bjerknes feedback mechanism, the thermocline effect (TE) is critically important to El Niño modeling. In this study, the potential influence of TE-related parametric uncertainties on El Niño is investigated using the conditional nonlinear optimal parametric perturbation (CNOP) method based on an intermediate coupled model (ICM). The optimal perturbation of the TE-related parameter (OTEP), which substantially affects El Niño simulations, is estimated through the CNOP approach. Results reveal that the El Niño simulation is highly sensitive to the TE uncertainty in the eastern equatorial Pacific, with OTEP-induced simulation errors demonstrating an El Niño-like growth trend. On one hand, as indicated by the simulated El Niño intensity, the uncertainty in the TE in the eastern region can easily affect the strength of the Bjerknes feedback-related thermocline effect and atmospheric circulation. On the other hand, the enhanced TE is highly favored to accelerate the growth of the SST error due to the air–sea interaction, thus severely affecting the El Niño simulations. Therefore, adequately representing the TE in the equatorial eastern Pacific is emphasized for effectively improving El Niño simulations.</p>\u0000 </section>\u0000 </div>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142525108","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}

{"title":"Seasonal Variability in Baffin Bay","authors":"Xuan Shan,&nbsp;Michael A. Spall,&nbsp;Clark Pennelly,&nbsp;Paul G. Myers","doi":"10.1029/2024JC021038","DOIUrl":"https://doi.org/10.1029/2024JC021038","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Three dominant characteristics and underlying dynamics of the seasonal cycle in Baffin Bay are discussed. The study is based on a regional, high-resolution coupled sea ice-ocean numerical model that complements our understanding drawn from observations. Subject to forcing from the atmosphere, sea ice, Greenland, and other ocean basins, the ocean circulation exhibits complex seasonal variations that influence Arctic freshwater storage and export. The basin-scale barotropic circulation is generally stronger (weaker) in summer (winter). The interior recirculation (∼2 Sv) is primarily driven by oscillating along-topography surface stress. The volume transport along the Baffin Island coast is also influenced by Arctic inflows (∼0.6 Sv) via Smith Sound and Lancaster Sound with maximum (minimum) in June-August (October-December). In addition to the barotropic variation, the Baffin Island Current also has changing vertical structure with the upper-ocean baroclinicity weakened in winter-spring. It is due to a cross-shelf circulation associated with spatially variable ice-ocean stresses that flattens isopycnals. Greenland runoff and sea ice processes dominate buoyancy forcing to Baffin Bay. Opposite to the runoff that freshens the west Greenland shelf, stronger salinification by ice formation compared to freshening by ice melt enables a net densification in the interior of Baffin Bay. Net sea ice formation in the past 30 years contributes to ∼25% of sea ice export via Davis Strait. The seasonal variability in baroclinicity and water mass transformation changes in recent decades based on the simulation.</p>\u0000 </section>\u0000 </div>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142451789","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}

{"title":"Quantifying the Role of Silicate and Dissolved Nitrogen in Co-Limiting the Primary and Secondary Productivity of the Bay of Bengal Euphotic Zone","authors":"Inakonda Veera Ganga Bhavani,&nbsp;Faseela Hamza,&nbsp;B. R. Smitha,&nbsp;Vinu Valsala","doi":"10.1029/2024JC021009","DOIUrl":"https://doi.org/10.1029/2024JC021009","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>A single-column coupled physical and biological model based on the North Pacific Ecosystem Model for Understanding Regional Oceanography (NEMURO) with nitrogen and silicon cycles is adapted for the Bay of Bengal (BoB) environment. The model simulated plankton biomass and nutrients along the track of Bio-Argos over East and West BoB (from 2016 to 2017) are validated with the observations. The model reasonably simulates the perennial structure of subsurface chlorophyll maximum (SCM). Further, three experiments are carried out to know the limitations in primary and secondary production in terms of nitrogen (NO₃ + NH₄) and silicate (Si(OH)₄) in the open ocean BoB. In a “no-NO₃”experiment, the nitrate limiting term [that is, NO₃/(NO₃ + KNO₃)] is set to zero so that the difference from the control case gives the role of “regenerated production” in the total primary and secondary production. Similarly, a no-NH₄ experiment was conducted to infer the role of “new production.” The new (regenerated) production fuels 85 ± 1% (28 ± 6%) of the living biomass in the East part of open ocean BoB (East BoB). The corresponding values for the west part (West BoB) are 86 ± 1% (42 ± 2%). Among the primary producers, the new (regenerated) production contributed 72 ± 1% (24 ± 6%) in the East BoB and 74 ± 1% (37 ± 2%) in the West BoB. The silicate limits the diatom production by 46% ± 22% (45% ± 27%) of the actual amount of diatom in the East BoB (West BoB) diatom. Surface to 60 m depth, we observed severe nitrate limitation over East BoB and equal limitation of nitrate and silicate over West BoB from June to September; the remaining months suffered from moderate nitrate limitation in both regions. This study shows that nitrate appears to be a limiting nutrient compared to silicate at the surface of both East and West BoB. Since silicicline is deeper than nitracline, silicate is the potential limiting nutrient in BoB from 65 to 105 m depth in all seasons.</p>\u0000 </section>\u0000 </div>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142451790","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}

{"title":"Mechanisms of Reappeared Period Shifts of Internal Solitary Waves Based on Mooring Array Observations in the Northern South China Sea","authors":"L. Xie,&nbsp;L. Chen,&nbsp;Q. Zheng,&nbsp;G. Wang,&nbsp;J. Yu,&nbsp;X. Xiong,&nbsp;W. Jiang,&nbsp;P. Zhang,&nbsp;Z. Zhang","doi":"10.1029/2023JC020389","DOIUrl":"https://doi.org/10.1029/2023JC020389","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Mooring observations have revealed that the daily reappeared time (DRt) of internal solitary waves (ISWs) in the northern South China Sea (SCS) manifests systematic shifts. This study aims to reveal the dynamic mechanisms behind this phenomenon using the theory of modulation of shear flow to the internal tide wave (IT) propagation. Approximate solutions for the frequency modulation function (FMF) and the amplitude modulation function (AMF) of ITs are derived and validated by the mooring array measurements on the northern SCS continental shelf in 2019 and 2020. Namely, the mechanisms of the ISW reappeared period shift (RPS derived from DRt) and amplitude variation are attributed to the modulation of low-frequency flow with a period of about 7 days to ITs. The FMF is induced by the vorticity of the low-frequency flow (FS1) and the Doppler shift (FS2). Thus, the sign of the FMF value may be positive (blue shift) and negative (red shift), depending on the algebraic summation of the two terms. The FS2 derived from mooring observed velocities confirms the modulation effects of mean current on the frequency shift and the amplitude variation of ITs and ISWs.</p>\u0000 </section>\u0000 </div>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JC020389","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142451755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elevated Mixing Estimates and Trapped Near-Inertial Internal Waves on the Inshore Flank of the New Guinea Coastal Undercurrent From Sustained Glider Observations in the Solomon Sea","authors":"T. M. Shaun Johnston,&nbsp;Daniel L. Rudnick,&nbsp;William S. Kessler","doi":"10.1029/2024JC021626","DOIUrl":"https://doi.org/10.1029/2024JC021626","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>The Solomon Sea is a major contributor to (a) the volume transport into the Equatorial Undercurrent and (b) the associated heat transport, which has an order one effect on interannual temperature variability on the equator according to previous work. The narrow western boundary current (New Guinea Coastal Undercurrent, NGCU) merges with the broad, shallow North Vanuatu Jet within 100 km of the southern entry to the sea, which implies mixing. Existing estimates from observations suggest mixing is larger than in models with different mixing parameterizations, which produce disparate properties of these exiting waters. Here, we use sustained underwater glider measurements across the Solomon Sea from 2007 to 2020 to examine the spatial variability of mixing estimates and internal waves. We estimate diffusivity via a finescale parameterization using the vertical strain of isopycnal displacements from internal waves. A typical accuracy of this parameterization when compared to turbulence measurements is within a factor of 2–3. Our results and previous observations in this area agree within this factor. Our main results are: (a) vertical diffusivity estimates are about <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>4</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${10}^{-4}$</annotation>\u0000 </semantics></math> <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>m</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{m}}^{2}$</annotation>\u0000 </semantics></math> <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>s</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${mathrm{s}}^{-1}$</annotation>\u0000 </semantics></math> on the inshore, anticyclonic side of the NGCU, which are 10–100 times higher than offshore and (b) elevated near-inertial internal wave (NIW) amplitudes are also found inshore. Taken together, these results suggest trapping of NIW by the anticyclonic vorticity of the NGCU leads to the elevated mixing within 100 km of the entry to the Solomon Sea.</p>\u0000 </section>\u0000 </div>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":null,"pages":null},"PeriodicalIF":3.3,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142451776","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}