Journal of Geophysical Research-Oceans最新文献

{"title":"The Role of Dynamic Seepage Response in Sediment Transport and Tsunami-Induced Scour","authors":"Zhengyu Hu,&nbsp;Wen-Gang Qi,&nbsp;Yuzhu Pearl Li","doi":"10.1029/2024JC021084","DOIUrl":"https://doi.org/10.1029/2024JC021084","url":null,"abstract":"<p>Tsunamis have long been recognized to destabilize the seabed by causing severe erosion and potential liquefaction. However, the effect of the dynamic seepage response induced by tsunami loading on sediment transport remains elusive. Here, we explicitly quantify the role and mechanics of seepage response in field-scale tsunami-induced bed mobility and scour through theoretical analyses and fully coupled hydrodynamic and morphological simulations. The increased hydraulic gradient can lower the onset threshold of the sediment motion, thus facilitating sediment transport. In the meantime, it can also curtail the fluid–sediment momentum transfer, consequently weakening sediment transport. The competing effects of seepage response on the onset threshold and fluid agitation are such that the seepage response during the depression wave does not necessarily increase bed mobility. The suspended load transport can dominate the near-field scour processes, as demonstrated with the scour beneath a submarine pipeline. The seabed suction response to the elevation wave shows insignificant effects on the continuous exchange between the suspended load and bed load, although it inhibits the near-bed sediment concentration. The seabed injection response to the depression wave induces more bed load particles to be entrained into the water column, contributing to the increased concentration. This results in increased sediment transport and exacerbated scour, especially for the bed liquefaction scenario. The seepage response plays a critical role in the spatiotemporal variations of the seabed morphology and the sediment suspension. The outcomes significantly update the knowledge about the role of seepage in the progress of tsunami-induced sediment transport and scour.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021084","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689380","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":"Geochemical Fingerprinting of Siboglinid Tube Worms: Insights From Stable Isotopes (C, N, and S) and Trace Elements","authors":"Zice Jia,&nbsp;Niu Li,&nbsp;Jörn Peckmann,&nbsp;Xudong Wang,&nbsp;Junxi Feng,&nbsp;Bolin Zhuo,&nbsp;Na Cui,&nbsp;Zenggui Kuang","doi":"10.1029/2024JC022177","DOIUrl":"https://doi.org/10.1029/2024JC022177","url":null,"abstract":"<p>At marine methane seeps, siboglinid tube worms influence the exchange of elements between sediments and seawater and potentially represent a recorder of seep activity. The organ of siboglinids produces the chitin of the tube wall, facilitating the formation of tubes that protect the siboglinid's soft tissue. However, the mechanisms underlying element transfer and isotope fractionation between soft tissue and the chitinous tube are poorly constrained. This study analyzes the carbon, nitrogen, and sulfur isotopes as well as trace elements, including rare earth elements (REEs) and copper (Cu), compositions of tissues and tubes of the siboglinid tube worm <i>Paraescarpia echinospica</i> from the Haima seeps of the South China Sea. The stable isotope values of both tissue and the chitinous tube primarily reflect sulfur oxidation processes and carbon fixation by endosymbiotic sulfur-oxidizing bacteria. The trace element composition of the soft tissue suggests the utilization of light rare earth elements (LREEs) and Cu during aerobic oxidation of methane supposedly performed by epibiotic aerobic methanotrophic bacteria. In contrast, the trace element composition (e.g., REEs, Cu) of the chitinous tube primarily records the influence of diagenetic processes and source effects. The chitinous tube is therefore apparently not a straightforward archive of the local environment and metabolic characteristics of the tube worms. Still, the discrepancies between the information stored in tissue and the chitinous tube may offer some insight for the identification of fossil seep-dwelling tube worms if parts of the chitinous tube are preserved. Integrating element and isotope geochemistry within paleontological studies may consequently enhance our understanding of siboglinid evolution.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689529","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":"Infragravity Frequency Wave-Driven Bottom Boundary Layer Turbulence in Shallow Estuaries","authors":"Duncan C. Wheeler,&nbsp;Sarah N. Giddings,&nbsp;Mark Merrifield,&nbsp;Geno Pawlak","doi":"10.1029/2024JC021284","DOIUrl":"https://doi.org/10.1029/2024JC021284","url":null,"abstract":"<p>We use turbulent dissipation measurements from a small estuary to determine how and when infragravity (IG) waves (periods <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>25–250 s) increase turbulence due to bottom friction. The frequency of IG waves leads to a larger wave boundary layer than for sea and swell waves. Current methods for predicting turbulence from mean currents rely on observations in regions of the water column where oscillating velocities either have a logarithmic or depth-uniform profile. We develop a new approach for predicting turbulent dissipation in the unsteady boundary layer regime that combines a quasi-steady regime at the bottom of the water column and an outer regime above the wave boundary layer. Using a numerical model and observations from Los Peñasquitos Lagoon, we find that the new approach allows for calculation of average turbulent dissipation rates throughout the entire water column and performs better than existing methods when calculating turbulent dissipation within the wave boundary layer. Our observations indicate IG waves increase turbulent dissipation across a substantial fraction of the water column when the mean current amplitude is less than <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>3</mn>\u0000 <mo>/</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation> $3/2$</annotation>\u0000 </semantics></math> of the current standard deviation. These conditions were typically observed during neap flood tides or at the very beginning and the end of spring flood tides. In addition, we find that the wave boundary layer height can be estimated from the instantaneous bottom stress, consistent with existing scaling approaches. Finally, we show that IG wave-induced increases in turbulence appear associated with sediment transport inside the estuary.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021284","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689528","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":"Assessing Deep and Abyssal Ocean Heat Content Changes With a Dynamically Consistent Ocean State Estimate","authors":"Yang Zhang,&nbsp;Xinfeng Liang,&nbsp;Don P. Chambers,&nbsp;Minghai Huang","doi":"10.1029/2024JC020925","DOIUrl":"https://doi.org/10.1029/2024JC020925","url":null,"abstract":"<p>Because of the sparseness of existing observations, our understanding of deep (2,000–4,000 m) and abyssal (&gt;4,000 m) ocean heat content (OHC) changes remains limited. Previous studies utilizing repeated hydrographic section measurements identified a global warming trend in these layers. However, studies based on a widely used ocean state estimate ECCO v4 (Estimating the Circulation and Climate of the Ocean, version 4) show a contradictory cooling trend in the deep and abyssal Pacific and Indian Oceans. To examine if the sparseness of hydrographic measurements results in this contrasting conclusion, we conducted a sampling experiment with ECCO v4. Our results show that the signs of the OHC trends in the deep and abyssal oceans from the full spatial-temporal data and the sampled data are generally consistent. The largest uncertainties mainly occur in regions where the deep ocean is dominated by newly formed deep-water masses or where hydrographic sections are extremely sparse, such as the Northwest Atlantic Ocean and the Southern Ocean. Our findings also indicate that the discrepancies between ECCO v4 and observations in deep and abyssal OHC changes are not likely a sampling issue, and further studies are needed to determine the reasons.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC020925","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143688935","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":"Accounting for Horizontal Tracer Gradients in Biological Productivity Estimates From Semi-Lagrangian Platforms","authors":"Marin Cornec,&nbsp;Andrea J. Fassbender","doi":"10.1029/2024JC021628","DOIUrl":"https://doi.org/10.1029/2024JC021628","url":null,"abstract":"<p>Marine net community production (NCP), a metric of ecosystem functionality, is often estimated as the residual term in a mass balance equation that aims to describe upper ocean variations in the time series of a chemical tracer. The advent of biogeochemical (BGC) Argo profiling floats equipped with nitrate, pH, and oxygen sensors has enabled such NCP estimation across vast ocean regions. Floats typically drift at 1,000 m depth between profiling from ∼2,000 m to the surface every 10 days, resulting in quasi-Lagrangian time series that can reflect different upper ocean water masses over time. However, limited information about real-time horizontal tracer gradients often leads to lateral processes being omitted during tracer budget closure, which can bias the residual-term NCP estimates. To determine the potential magnitude of such biases, we developed a method to quantify and adjust for the impact of lateral float movement across horizontal tracer gradients using dissolved inorganic carbon (DIC) as our case study. We evaluated the method by extracting artificial float profiles from a depth-resolved observation-based DIC product to generate an artificial DIC time series. We then estimated NCP before and after accounting for horizontal gradient effects and compared the results to NCP estimates from an artificial DIC time series extracted at a fixed location along the float trajectory. Testing 10 biogeographical domains with moderate to substantial horizontal DIC gradients, our method significantly improved the precision (by ∼50 to ∼80%) and accuracy (by ∼10 to ∼100%) of regional NCP estimates. This method can be applied to other tracers with multi-month-long residence times.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021628","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143646277","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":"Observed Seasonality of Mixed-Layer Eddies and Vertical Heat Transport Over the Antarctic Continental Shelf","authors":"Sophia Spungin,&nbsp;Yidongfang Si,&nbsp;Andrew L. Stewart,&nbsp;Channing J. Prend","doi":"10.1029/2024JC021564","DOIUrl":"https://doi.org/10.1029/2024JC021564","url":null,"abstract":"<p>The Antarctic continental shelf (ACS) hosts processes that impact the climate system globally, which has motivated ongoing efforts to characterize its state, circulation, and variability. However, the nature and consequences of eddies over the ACS, and their contributions to the budgets of heat and freshwater, remain systematically understudied. This study uses hydrographic measurements collected from instrumented seals, supported by a high-resolution model of the southern Weddell Sea, to characterize eddies and their role in vertical heat transport around the entire ACS. A key finding is that eddies are ubiquitous, and exhibit frequent (2%–10% of hydrographic casts) occurrences of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>O</mi>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mn>1</mn>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation> $mathcal{O}(1)$</annotation>\u0000 </semantics></math> bulk Richardson numbers, indicative of submesoscale variability. However, along-track density power spectra exhibit wavenumber dependences of <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <msup>\u0000 <mi>k</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>3</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${sim} {k}^{-3}$</annotation>\u0000 </semantics></math>, consistent with quasigeostrophic turbulence. Approximately <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>0.3</mn>\u0000 <mi>%</mi>\u0000 </mrow>\u0000 <annotation> $0.3%$</annotation>\u0000 </semantics></math> of the points in the surface mixed layer satisfy conditions favorable for symmetric instability, although its prevalence is likely higher than this due to the relatively coarse resolution of the seal tracks. Vertical heat transports, estimated from a regional model-calibrated parameterization of submesoscale restratification, are largest in shelf regions hosting dense water, which have previously been identified as key sites of warm water intrusions onto the ACS. These regions also exhibit the largest seasonal cycles, with elevated winter eddy activity and heat fluxes accompanying the formation of high salinity shelf waters. These findings indicate that eddies may contribute substantially to ACS heat and tracer budgets, and motivate further study of their role in determining the pathways and fate of heat that intrudes onto the ACS.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021564","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143646278","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":"Abrupt Changes in the Timing and Magnitude of the North Atlantic Bloom Over the 21st Century","authors":"Stephen Kelly,&nbsp;Ekaterina Popova,&nbsp;Andrew Yool,&nbsp;Fatma Jebri,&nbsp;Sophy Oliver,&nbsp;Meric Srokosz","doi":"10.1029/2024JC022284","DOIUrl":"https://doi.org/10.1029/2024JC022284","url":null,"abstract":"<p>The North Atlantic subpolar gyre (SPG) is a key region for the North Atlantic bloom (NAB), the phytoplankton foundation of the regional food web. The NAB depends on nutrients seasonally introduced into the surface ocean by deep winter convection. Under climate change, this pattern is threatened by increasing water column stratification, representing a potential “tipping point” in the Earth system, and may “collapse” as a result. We investigate changes in winter mixing and the impacts on the SPG and the northern North Atlantic using a spread of future projections from a low-resolution Earth system model (UKESM) and a high-warming projection of a high-resolution ocean-only configuration of the same model (NEMO-MEDUSA). Both models project significant declines in the strength of the NAB during the 21st century. In UKESM, this occurs across all projections, but with low spatiotemporal coherence. In NEMO-MEDUSA, changes in mixed layer depth, nutrients, and chlorophyll concentrations are abrupt and more highly spatiotemporally correlated. We find a &gt;30-day phenological shift in the peak of the bloom aligned with the timing of this change, which may affect food web dynamics. Defining “collapse” as halving of surface chlorophyll, we find that the NAB collapses this century regardless of future projection. However, the spatial-temporal coherence of the timing and abruptness of this collapse is greater in our high-resolution model. Because key physical processes driving biogeochemical responses are poorly represented in low-resolution models, especially at high latitudes, this suggests that higher resolution may be essential for predicting abrupt and irreversible changes, particularly those involving ecosystem dynamics.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022284","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143646317","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":"Sea Ice Meltwater in the Beaufort Gyre: A Comprehensive Analysis Using Sea Surface Salinity Data From SMOS","authors":"Eva De Andrés,&nbsp;Marta Umbert,&nbsp;María Sánchez-Urrea,&nbsp;Verónica González-Gambau,&nbsp;Estrella Olmedo,&nbsp;Carolina Gabarró,&nbsp;Pedro Elosegui","doi":"10.1029/2023JC020733","DOIUrl":"https://doi.org/10.1029/2023JC020733","url":null,"abstract":"<p>Arctic sea ice is retreating. In the Beaufort Gyre (BG), liquid freshwater content (FWC) has increased by 40% in the last two decades, with sea ice melting being one of the contributors. Combining satellite observations and reanalysis outputs, we study the sea ice meltwaters in the BG from 2011 to 2019. SMOS sea surface salinity (SSS) data were limited to the ice-free period, and reanalysis outputs showed limited accuracy in capturing the postmelt freshening observed in SMOS SSS. Applying criteria of SSS <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&lt;</mo>\u0000 </mrow>\u0000 <annotation> ${&lt; } $</annotation>\u0000 </semantics></math>25 psu and sea ice presence, we identified meltwater lenses (MWLs) across different years with higher frequency in 2011, 2015, and 2016, contrasting with scarcity in 2012, 2017, and 2019. MWLs showed lower SSS and temperature than river-influenced waters. Daily evolution of SSS and sea ice area within the MWLs exhibited similar patterns during both melting and formation stages. Furthermore, events of sea surface salinification following sea ice formation suggest that SMOS SSS might be capturing information on brine rejection. Atmospheric conditions suggested that the anticyclonic wind regime in 2011 contributed to meltwater retention, while the cyclonic wind pattern in 2016 favored outward meltwater dispersion. From our estimations, September's sea ice melting may contribute 10%–30% of the BG's annual FWC increase, though our method likely underestimates meltwater volume due to unaccounted advection processes. This study provides a validated method for MWL detection and underscores the importance of monitoring sea ice meltwaters to better understand regional variability in the BG within a changing climate.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143646279","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":"Eddy-Driven Cross-Shelf Exchange and Variability in the East Auckland Current","authors":"Rafael Santana,&nbsp;Joanne O’Callaghan,&nbsp;Helen Macdonald,&nbsp;Sutara H. Suanda,&nbsp;Sarah Wakes","doi":"10.1029/2024JC021601","DOIUrl":"https://doi.org/10.1029/2024JC021601","url":null,"abstract":"&lt;p&gt;Using an ocean reanalysis and freely evolving numerical simulation, eddy-driven cross-shelf exchange in the East Auckland Current (EAuC) system was investigated. The EAuC is stronger in the reanalysis than the free run and has a more evident impact on cross-shelf exchange. Despite differences in the EAuC strength, both simulations produced similar small-eddy (radius &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${&lt; } $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;30 km) statistics, which supports the robustness of the reanalysis considering that data assimilation could generate unrealistic variability. These 1-year simulations revealed mechanisms by which the EAuC and its eddy variability drive water exchange between the continental shelf and the slope that depend on its proximity to the shelfbreak. At times and locations where the EAuC is attached to the continental slope, onshore bottom Ekman transport with variability between 4 and 60 days results in cross-isobath exchange. However, EAuC-driven bottom Ekman transport is smaller than the total volume that crosses the shelfbreak (1%–12%), which is largely controlled by submesoscale variability. An eddy-tracking algorithm was used to identify, classify, and analyze eddy-driven impact on cross-shelf exchange in both runs. Cyclonic eddies generated cross-shelf exchange by exporting up to 291 &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mtext&gt;km&lt;/mtext&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{km}}^{3}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; of shelf waters to the open ocean. Coastal cyclones are small eddies (radius &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${&lt; } $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;18 km) formed on the continental shelf via shear instability and have submesoscale characteristics (Rossby and Richardson numbers &lt;i&gt;O&lt;/i&gt;(1)) and are more efficient in generating cross-shelf exchange than larger eddies. Slope cyclones form in deeper waters (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;&gt;&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${ &gt;} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;200 m) and have transitional characteristics between submesoscale and the large mesoscale eddies (radius &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;&gt;&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${ &gt;} $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;50 km). These larger mesoscale eddies did not have an impact on cross-shelf e","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021601","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143646318","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":"Spectral Wave Energy Dissipation by a Seagrass Meadow","authors":"Nery Contti Neto,&nbsp;Ryan J. Lowe,&nbsp;Marco Ghisalberti,&nbsp;Andrew Pomeroy,&nbsp;Matthew Reidenbach,&nbsp;Mario Conde-Frias,&nbsp;Renan F. da Silva","doi":"10.1029/2024JC020938","DOIUrl":"https://doi.org/10.1029/2024JC020938","url":null,"abstract":"<p>Existing formulations for predicting wave dissipation by submerged canopies generally fall into three categories where (a) an empirical coefficient (energy dissipation factor) is attributed to the canopy ignoring its physical properties; (b) estimates of canopy drag forces based on a bulk drag coefficient and undisturbed velocities above the canopy are used to estimate dissipation; and (c) canopy flow theory is used to account for how modifications to in-canopy flows influence canopy forces and associated dissipation. We measured rates of spectral wave dissipation across a dense seagrass meadow comprised of <i>Posidonia australis</i> in southwestern Australia, which also included high-resolution flow measurements within and above the seagrass canopy. These observations were used to quantify the effectiveness of the three different approaches to predict observed rates of spectral wave dissipation. The results showed that conventional approaches that do not account for canopy flow modifications and/or seagrass flexibility tend to overestimate both bulk and frequency-dependent wave dissipation. Conversely, approaches that consider frequency-dependent flow attenuation in canopies were found to improve predictions of wave dissipation, particularly when also accounting for how the deflection of flexible seagrass blades induced by flow modifies the effective canopy height. The results show that the canopy flow velocities induced by short period wind waves were less attenuated than longer period swell, explaining the frequency dependency of rates of wave dissipation, with shorter period wave heights being more efficiently attenuated by the meadow.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 3","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC020938","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143646316","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}