Journal of Marine Systems最新文献

{"title":"Comparative study of the variability and trends of phytoplankton biomass between spring and winter upwelling systems in the South China Sea","authors":"Jialing Zeng ,&nbsp;Chunli Liu ,&nbsp;Xue Li ,&nbsp;Hui Zhao ,&nbsp;Xiaoling Lu","doi":"10.1016/j.jmarsys.2022.103738","DOIUrl":"10.1016/j.jmarsys.2022.103738","url":null,"abstract":"<div><p><span>High phytoplankton biomass usually appears off the coastal waters southeast of Vietnam (SV) during summer and southwest of the Luzon Strait (SLS) in winter. Although this seasonal upwelling has been recognized in SV and SLS for more than half a century, there has been limited documentation comparing the characteristics and formation mechanisms of these two upwelling systems. To understand the dynamic features of phytoplankton growth in SV and SLS, seasonal and interannual variabilities of Chlorophyll-</span><em>a</em> (Chl-<em>a</em>) concentration were studied based on decadal-scale satellite-derived datasets (2003–2018). Bivariate wavelet coherence (BWC) and multiple wavelet coherence (MWC) were performed to evaluate the temporal variability of multiple controlling factors. The results demonstrated that there were different patterns of seasonal cycles and interannual variability of Chl-<em>a</em> concentrations in the two upwelling regions. In SV, high Chl-<em>a</em><span> concentrations during summer were primarily formed by the interactions of multiple factors, causing the mixed layer depth to increase during summer and sufficient nutrient concentrations on the surface (supplied by the mixed water column). In contrast, the high Chl-</span><em>a</em><span> concentrations in SLS are caused by a combination of deep mixing (induced by wind and buoyancy forcing) and enhanced upward advection<span> (induced by strong eddy activities). These factors support intense levels of phytoplankton biomass during winter. The sea surface temperature (SST) was the best single factor to explain the Chl-</span></span><em>a</em> variance in both regions. The addition of more factors to the MWC analysis changed the main factors influencing the Chl-<em>a</em> variations. The two-factor combination of SST-Niño 3.4 in SV and the SST-mixed layer depth (MLD) in SLS controlled the Chl-<em>a</em> variations on an interannual scale. Moreover, the three-factor combination of SST-Niño 3.4-MLD was still meaningful for explaining the Chl-<em>a</em> variations. This indicated that the influencing the Chl-<em>a</em> variations differed in these two upwelling systems.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"231 ","pages":"Article 103738"},"PeriodicalIF":2.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44521643","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling suspended particulate matter dynamics at an Antarctic fjord impacted by glacier melt","authors":"Camila Neder ,&nbsp;Vera Fofonova ,&nbsp;Alexey Androsov ,&nbsp;Ivan Kuznetsov ,&nbsp;Doris Abele ,&nbsp;Ulrike Falk ,&nbsp;Irene R. Schloss ,&nbsp;Ricardo Sahade ,&nbsp;Kerstin Jerosch","doi":"10.1016/j.jmarsys.2022.103734","DOIUrl":"10.1016/j.jmarsys.2022.103734","url":null,"abstract":"<div><p>When Antarctic glaciers retreat, high sediment loads from geomorphological and glaciological sources can disturb the biota, especially filtering organisms, and thereby significantly alter the ecology of the Antarctic coast. We applied the Finite volumE Sea-ice Ocean-Coastal Model (FESOM-C), a numerical tool equipped with a sediment module, to simulate for the first time the suspended particulate matter (SPM) dynamics in a fjordic environment at the northern West Antarctic Peninsula, Potter Cove as a case study. Depth-averaged SPM dynamics during a meteorologically representative austral summer (120 days from December to March) considered tidal and atmospheric forcing. Additionally, idealised experiments with passive particles based on post-processing Lagrangian module identified and followed possible material trajectories in Potter Cove. Particle dynamics in the area show them to be primarily tidal and wind-driven, sensitive to bathymetry, with the higher SPM concentrations in the inner cove and the highest hydrographical complexity in the transitional area between the fjordic and marine habitat. The SPM plume covers 5.5 km² of the total inlet of 9 km², with monthly mean values between 15 and 330 mg/l. The maximum SPM concentrations are during January (790 mg/l), and the maximum plume expansion during February. The model was validated with available in situ measurements. With this study, we can identify areas in Potter Cove (and similar coastal fjordic environments, prospectively) of increasing physical stress by longer SPM residence time and high accumulation rates induced by glacial meltwater. These factors are crucial for pelagic and benthic assemblages dependent on light and food availability, as well sediment deposition.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"231 ","pages":"Article 103734"},"PeriodicalIF":2.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0924796322000355/pdfft?md5=d951532382db9c43c648837a63f47d77&pid=1-s2.0-S0924796322000355-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47844636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"The multi-year comparisons of chlorophyll and sea ice in Greenland Sea and Barents Sea and their relationships with the North Atlantic Oscillation","authors":"Bo Qu ,&nbsp;Albert J. Gabric","doi":"10.1016/j.jmarsys.2022.103749","DOIUrl":"https://doi.org/10.1016/j.jmarsys.2022.103749","url":null,"abstract":"<div><p><span>The Arctic Ocean (AO) has experienced very significant warming in recent decades with clear impacts on the extent and depth of sea ice cover. Sea ice serves as a primary habitat and plays an important role in the AO marine food web. The surface distributions of chlorophyll_</span><em>a</em><span><span><span><span> (CHL), sea ice concentration (ICE), sea surface temperature (SST) and </span>North Atlantic Oscillation<span> (NAO) are analyzed in the study region (20°W-50°E, 70°N-80°N) over the decade (2003–2014). This region spans the Barents Sea (BS), Norwegian (NS) and Greenland Sea (GS). In general, the peak of spatial averaged CHL in the BS was about 60% higher than the GS. Due to elevated SST in the southern BS, CHL was much higher especially in 2010 and 2013. In 2011, there was a strong meridional gradient in CHL decreasing from south to north of the BS, and also a strong zonal gradient from the southern GS to the southern BS. The northern GS had higher CHL than the southern GS due to the increased ice melting and nutrient-enriched runoff from east Greenland </span></span>glaciers<span> to the northern and western coastal regions of the GS. Seasonal peaks of spatially averaged CHL occurred in April or May and were about two weeks earlier in the BS than the GS. Higher ice melt in the northern BS was the main reason for CHL blooms especially in 2010 and 2011. Earlier and more extensive ice melting and a persistent negative NAO index causing atmospheric circulation patterns that favoured ice loss were the possible drivers of enhanced </span></span>phytoplankton blooms in 2010. A previous negative winter NAO is thought to be linked to an increase in ICE in the following spring. NAO is mostly negative during spring in the GS. Sea ice melt was positively correlated with CHL in the northern sector of the study region.</span></p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"231 ","pages":"Article 103749"},"PeriodicalIF":2.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71855789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Trace elements V, Ni, Mo and U: A geochemical tool to quantify dissolved oxygen concentration in the oxygen minimum zone of the north-eastern Pacific","authors":"Alberto Sánchez,&nbsp;Evgueni Shumilin,&nbsp;Griselda Rodríguez-Figueroa","doi":"10.1016/j.jmarsys.2022.103732","DOIUrl":"10.1016/j.jmarsys.2022.103732","url":null,"abstract":"<div><p><span><span><span>Deoxygenation of the water column in the oceans and in the oxygen minimum zone (OMZ) has become relevant due to its connection with global climate change. The variability of the OMZ has been inferred by </span>in situ measurements for the last 70 years and qualitatively assessed through the monitoring of trace elements and the nitrogen </span>stable isotope ratio (δ</span>¹⁵N) of organic matter on several time scales. The V, Ni, Mo and U concentrations in surface sediments and the dissolved oxygen concentration in the water column of La Paz Bay and the Mazatlán margin were used to propose an exponential regression model. This model will allow the inference of the dissolved oxygen concentration in the sedimentary records from the Alfonso Basin in La Paz Bay and in the Mazatlán margin over the last 250 years. Based on this exponential regression model, the dissolved oxygen concentration increased by 6.4 μM in the Alfonso Basin and 4.1 μM in the Mazatlán margin, in the period between 1800 CE and the present day. This suggests a reoxygenation of the OMZ at the mouth of the Gulf of California. This finding is consistent with previous studies (Deutsch et al., 2014; Tems et al., 2016), which suggest a reduction in the deoxygenation of the water column throughout most of the 20th century.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"230 ","pages":"Article 103732"},"PeriodicalIF":2.8,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42466297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of bottom currents for estimating their erosional-depositional potential in the Southwest Atlantic","authors":"Dmitry Frey ,&nbsp;Dmitrii Borisov ,&nbsp;Vladimir Fomin ,&nbsp;Eugene Morozov ,&nbsp;Oleg Levchenko","doi":"10.1016/j.jmarsys.2022.103736","DOIUrl":"10.1016/j.jmarsys.2022.103736","url":null,"abstract":"<div><p>Contourites<span> are sediments deposited or substantially reworked by the persistent action of bottom currents which are capable of forming a wide range of erosional and depositional features on the seafloor. The study of contourites is a multidisciplinary topic linking physical oceanography<span><span> and marine geology. While near-bottom circulation is an important subject itself due to different dynamic aspects and climatic estimates of abyssal water transports, it becomes especially important for studies of lateral sedimentation. The precise direct data on bottom currents on the South American </span>continental rise<span> and adjacent abyssal plains<span><span> remain extremely rare. Numerical modeling can appear helpful for filling the gaps in our knowledge on bottom circulation in the region. This work describes an approach for mapping erosion- and deposition-dominated areas based on the modeled circulation in the bottom layers. The model domain covers the regions with different </span>seabed topography and velocities of bottom currents: the Vema Channel, the Santa Catarina Plateau, the Rio Grande Rise, and parts of the Argentine and Brazil basins. The high vertical resolution used in the model allowed us to study the near-bottom circulation in the deep ocean, while high horizontal resolution enabled modeling currents in narrow underwater passages such as the Vema Channel.</span></span></span></span></p><p>The equations that encompass the bottom current velocities<span> and data on surface sediment grain-size are well-known; in this study, we estimate the erosional-depositional potential of bottom currents using these equations. This approach allowed identification of the regions of dominant erosion (to the northeast of the northern exit from the Vema Channel), deposition (northern part of the Santa Catarina Plateau), and non-deposition under the influence of bottom currents. The results were validated by the analysis of echo-facies distribution in the study area and variations in the surface sediment grain-size. This study embraces the transition zone between the Argentine and Brazil basins, which is crucial for understanding the deep and bottom circulation in the western South Atlantic under modern conditions and in the geological past. The presented technique can improve our knowledge on how bottom currents shape the seafloor and control sediment distribution in the Southwest Atlantic.</span></p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"230 ","pages":"Article 103736"},"PeriodicalIF":2.8,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45985106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Internal tide-induced turbulent mixing and suspended sediment transport at the bottom boundary layer of the South China Sea slope","authors":"Haonan Wang ,&nbsp;Yonggang Jia ,&nbsp;Chunsheng Ji ,&nbsp;Wensheng Jiang ,&nbsp;Changwei Bian","doi":"10.1016/j.jmarsys.2022.103723","DOIUrl":"10.1016/j.jmarsys.2022.103723","url":null,"abstract":"<div><p><span>Internal tides produce significant vertical and horizontal flows in the ocean and cause strong turbulent mixing that is essential for the energy cascade of multiscale dynamic processes. However, the effects of internal tides on turbulent mixing and sediment transport<span><span> in the ocean bottom boundary layer remain unclear due to limited observations. In this study, a seabed-based monitoring platform was placed on the </span>continental slope<span> of the South China Sea (118° 09.80′E, 22° 03.78′N, water depth: 1145 m) to observe the internal tides and their influence on turbulent mixing and sediment transport at the bottom boundary layer for the first time. A primarily east-west direction of movement was observed with a maximum velocity of 0.41 m/s, which is much higher than regular barotropic tidal velocity (approximately 0.08 m/s) at the observation site. Influenced by the internal tides, the shear stress and the turbulent kinetic energy dissipation rate of the bottom boundary layer increased from 0.01 to 0.41 Pa and from 7.6 ×10</span></span></span>⁻⁶ to 5.6 ×10⁻⁴<span> W/kg, respectively. The enhanced shear stress and turbulent mixing led to the resuspension<span><span> of seabed sediment, and the bottom </span>suspended sediment concentration increased from 3.6 to 12.7 mg/L. In the process of upward propagation, the internal tides also carried the bottom sediment to a height of more than 300 m from the seabed. The sediment transport flux caused by internal tides reached 2.4 g/s/m</span></span>².</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"230 ","pages":"Article 103723"},"PeriodicalIF":2.8,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43353825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using Lagrangian coherent structures to investigate upwelling and physical process in the Gladstone coastal region","authors":"Anusmriti Ghosh ,&nbsp;Kabir Suara ,&nbsp;Tarmo Soomere ,&nbsp;Richard J. Brown","doi":"10.1016/j.jmarsys.2022.103731","DOIUrl":"10.1016/j.jmarsys.2022.103731","url":null,"abstract":"<div><p><span><span>Coastal upwelling plays an important role in the exchange of nutrients and pollutants. Understanding of upwelling and its predictors allows for important management of nutrient-enriched coastal waters. This study presents an analysis of coastal upwelling with a focus on Gladstone, Queensland (Australia). Particularly, Lagrangian coherent structures (LCSs) are used to quantify the spatio-temporal variability of upwellings, and to reveal the relationships between the surface mixing and physical properties of water masses and oceanographic activity in the Gladstone region. Four different seasonal selections of water surface velocity data (for summer, autumn, winter and spring) are compared with wind, </span>sea surface temperature<span> (SST), sea surface salinity and density data to investigate the coastal upwelling area. The surface mixing is calculated based on the backward Finite-Time Lyapunov Exponent (FTLE) diagnostic approach of LCSs. The strong </span></span>seasonality<span> of upwelling largely follows seasonal patterns of winds. Results highlight how upwelling behaviour varied with the intensity of cyclones. The core conclusion is that upwelling dynamics, estimated using classic means such as SST, have a strong correlation with the FTLE metric of LCSs. The potential upwelling hotspot shows that on average, it has 17.3% of its area above the FTLE threshold, compared to a non-upwelling area which has a corresponding percentage of 0.64%. This relationship makes it possible to define different upwelling locations, and properties of upwellings (e.g., seasonal variability, cyclone effect) as a function of FTLE, a derivative of the surface velocity field. Therefore, LCSs can be used to predict surface mixing and upwelling behaviour in coastal water systems.</span></p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"230 ","pages":"Article 103731"},"PeriodicalIF":2.8,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47763653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mid-summer vertical behavior of a high-latitude oceanic zooplankton community","authors":"Kanchana Bandara ,&nbsp;Sünnje L. Basedow ,&nbsp;Geir Pedersen ,&nbsp;Vigdis Tverberg","doi":"10.1016/j.jmarsys.2022.103733","DOIUrl":"10.1016/j.jmarsys.2022.103733","url":null,"abstract":"<div><p>Vertical behavior, such as diel vertical migration (DVM) and swarming are widespread among zooplankton. At higher latitudes, synchronized DVM is mostly absent during summer and predominantly herbivorous copepods tend to form large near-surface swarms. This behavior is risky because it can make them vulnerable to visual predators. Here, we used ca. 12 days of mid-summer (28 June to 10 July 2018) high-frequency acoustic data collected on board of an autonomous surface vehicle (Sailbuoy) to study the vertical behavioral patterns of a zooplankton community in the Norwegian Sea (69°–71° N). Comparing acoustic data with zooplankton net samples, we could distinguish the sound scatters into (1). lipid-rich older developmental stages of <em>Calanus</em> spp., (2). younger developmental stages of <em>Calanus</em> spp., smaller copepods and krill and (3). unknown group of strong sound scatters that may have been younger stages of planktivorous fish. We observed shorter-range classic DVM during much of the study period, where in two days, the migration appeared to be pronounced (&gt; 50 m in amplitude), largely synchronous and occurred in the presence of sound scatterer group 3. The observed zooplankton community was concentrated in the upper 20 m in cloudy and calm days but retreated to greater depths at increased near-surface turbulence. This turbulence-driven vertical retreat appeared to be synchronized across the zooplankton community, potentially indicating a schooling behavior.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"230 ","pages":"Article 103733"},"PeriodicalIF":2.8,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0924796322000343/pdfft?md5=8ee1679d2962e623617c0a75722b7b2c&pid=1-s2.0-S0924796322000343-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42794777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Coastal upwelling along the Uruguayan coast: Structure, variability and drivers","authors":"Camila de Mello ,&nbsp;Marcelo Barreiro ,&nbsp;Leonardo Ortega ,&nbsp;Romina Trinchin ,&nbsp;Gaston Manta","doi":"10.1016/j.jmarsys.2022.103735","DOIUrl":"https://doi.org/10.1016/j.jmarsys.2022.103735","url":null,"abstract":"<div><p><span><span>Summertime upwelling along the Uruguayan coast is studied for the first time using observational data and a high resolution regional ocean model. Simulations are performed with the CROCO model, with a horizontal resolution of 1/36° forced with NCEP-DOE daily mean winds and daily Río de la Plata discharges, together with climatological surface heat fluxes. A comparison between model results and actual observations indicates that the model reproduces seasonal, interannual and daily variability of the region. This allowed evaluating the role of the wind and freshwater discharge in the development of intense upwellings by running the model under different experimental setups. A Maximum Covariance Analysis<span> between daily mean NCEP-DOE winds and satellite sea surface temperature data (MUR-GHRSST) was performed to identify intense observed summer coastal upwelling. The simulations were used to characterize the horizontal and vertical structure of observed intense upwellings along the Uruguayan coast in terms of temperature, </span></span>salinity, vertical velocity and currents as well as their evolution for the first time. Finally, interannual simulations performed under different boundary conditions demonstrated the primary role of wind and secondary role of freshwater discharge anomalies in the generation of coastal upwelling. We also found that </span>La Niña<span> induces regional wind anomalies and river discharges that strongly favor upwelling in the Uruguayan estuarine coast, while El Niño does the opposite.</span></p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"230 ","pages":"Article 103735"},"PeriodicalIF":2.8,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71838326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variability of the diapycnal mixing coefficient in coastal oceans investigated with direct microstructure measurements","authors":"Eiji Masunaga ,&nbsp;S. Karan Venayagamoorthy ,&nbsp;Koyo Wada ,&nbsp;Hidekatsu Yamazaki","doi":"10.1016/j.jmarsys.2022.103722","DOIUrl":"10.1016/j.jmarsys.2022.103722","url":null,"abstract":"<div><p><span>Mass and heat fluxes in the ocean are important for understanding global ocean dynamics and ecosystems. Estimates of the diapycnal diffusivity (</span><em>K</em>_<em>ρ</em>) are required for quantifying these fluxes. In this regard, one of the key parameters that is required to estimate the diapycnal eddy diffusivity is the “mixing coefficient” (<em>Γ</em>). The diapycnal diffusivity is estimated from a combination of the rate of dissipation of turbulent kinetic energy <em>ε</em>, the buoyancy frequency <em>N</em> (a measure of background density stratification) and <em>Γ.</em> This study investigates how the mixing coefficient (<em>Γ</em>) may be inferred from field measurable parameters using in-situ direct microstructure measurements in coastal oceans. Four microstructure data sets were analyzed to investigate the variability of <em>Γ</em> and associated parameters. While <em>Γ</em> is found to vary widely within a range of <em>O</em>(10⁻³−10¹), it can be parameterized using a ratio of relevant turbulent length scales: the Ellison scale (<em>L</em>_<em>E</em>, which is approximately equivalent to the Thorpe scale) and the Ozmidov scale (<em>L</em>_<em>O</em>). When <em>L</em>_<em>E</em>/<em>L</em>_<em>O</em> is less than unity, the results show that <em>Γ</em> is proportional to (<em>L</em>_<em>E</em>/<em>L</em>_<em>O</em>)^4/3, consistent with previous observations. On the other hand, when <em>L</em>_<em>E</em>/<em>L</em>_<em>O</em> exceeds unity, <em>Γ</em> is approximately a constant with no discernable dependence on <em>L</em>_<em>E</em>/<em>L</em>_<em>O</em>, consistent with a recent theoretical and numerical study.</p></div>","PeriodicalId":50150,"journal":{"name":"Journal of Marine Systems","volume":"230 ","pages":"Article 103722"},"PeriodicalIF":2.8,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42638674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}