Meridional Section Research Articles

Friction Impact on the Accuracy of the Dependence of Micro-Hardness on Plastic Deformation in Testing Metals under Uniaxial Compression

Two sets of cylinder specimens with a height to diameter ratio of 1.5 made of annealed technical copper and AK12pch silumin were tested for uniaxial compression to different degrees of plastic deformation. At the first stage of the experiments, the ends of the specimen were ground on skins of different grain sizes and polished. Then the micro-hardness of the ends of each sample was measured. Micro-hardness measurements were carried out by the Vickers method at three loads on the indenter: 0.196, 0.490, and 0.980 N. At the second stage, the samples were cut along the meridional section, each sample was poured with a compound based on epoxy resin into an individual mold so that the meridional section of the cut sample came out onto the surface of the mold. After the process of grinding and polishing the meridional section, the micro-hardness of the center of the section was measured under the same loads that were used for measurements at the ends. At the third stage, the dependences of the micro-hardness on the intensity of plastic deformation were made. A comparative analysis of the indicated dependences, made from the results of measurements at the ends of the specimen and the surface of their meridional sections, showed that friction at the ends of the specimen during compression has a significant effect on the position of the dependence “micro-hardness - plastic deformation”. The evaluation of hardening based on the micro-hardness of the ends leads to significant errors.

Description of a global marine particulate organic carbon-13 isotope data set

Abstract. Marine particulate organic carbon stable isotope ratios (δ13CPOC) provide insights into understanding carbon cycling through the atmosphere, ocean and biosphere. They have for example been used to trace the input of anthropogenic carbon in the marine ecosystem due to the distinct isotopically light signature of anthropogenic emissions. However, δ13CPOC is also significantly altered during photosynthesis by phytoplankton, which complicates its interpretation. For such purposes, robust spatio-temporal coverage of δ13CPOC observations is essential. We collected all such available data sets and merged and homogenized them to provide the largest available marine δ13CPOC data set (https://doi.org/10.1594/PANGAEA.929931; Verwega et al., 2021). The data set consists of 4732 data points covering all major ocean basins beginning in the 1960s. We describe the compiled raw data, compare different observational methods, and provide key insights in the temporal and spatial distribution that is consistent with previously observed large-scale patterns. The main different sample collection methods (bottle, intake, net, trap) are generally consistent with each other when comparing within regions. An analysis of 1990s median δ13CPOC values in a meridional section across the best-covered Atlantic Ocean shows relatively high values (≥-22 ‰) in the low latitudes (<30∘) trending towards lower values in the Arctic Ocean (∼-24 ‰) and Southern Ocean (≤-28 ‰). The temporal trend since the 1960s shows a decrease in the median δ13CPOC by more than 3 ‰ in all basins except for the Southern Ocean, which shows a weaker trend but contains relatively poor multi-decadal coverage.

Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO)

Abstract. Detailed ocean currents in the southeastern tropical Indian Ocean adjacent to southern Sumatran and Javan coasts have not been fully explained because of limited observations. In this study, zonal current characteristics in the region have been studied using simulation results of a 1/8∘ global hybrid coordinate ocean model from 1950 to 2013. The simulated zonal currents across three meridional sections were then investigated using an empirical orthogonal function (EOF), where the first three modes account for 75 %–98 % of the total variance. The first temporal mode of EOF is then investigated using ensemble empirical mode decomposition (EEMD) to distinguish the signals. This study has revealed distinctive features of currents in the South Java Current (SJC) region, the Indonesian Throughflow (ITF)–South Equatorial Current (SEC) region, and the transition zone between these regions. The vertical structures of zonal currents in southern Java and offshore Sumatra are characterized by a one-layer flow. Conversely, a two-layer flow is observed in the nearshore and transition regions of Sumatra. Current variation in the SJC region has peak energies that are sequentially dominated by semiannual, intraseasonal, and annual timescales. Meanwhile, the transition zone is characterized by semiannual and intraseasonal periods with pronounced interannual variations. In contrast, interannual variability associated with El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) modulates the prominent intraseasonal variability of current in the ITF–SEC region. ENSO has the strongest influence at the outflow ITF, while the IOD's strongest influence is in southwestern Sumatra, with the ENSO (IOD) leading the current by 4 months (1 month). Moreover, the contributions (largest to smallest) of each EEMD mode at the nearshore of Java and offshore Sumatra are intraseasonal, semiannual, annual, interannual, and long-term fluctuations. The contribution of long-term variation (19.2 %) in the far offshore eastern Indian Ocean is larger than the interannual (16.3 %) and annual (14.7 %) variations. Future studies should be conducted to investigate this long-term variation.

Evaluation of regional climate models and future wind characteristics in the Black Sea

AbstractThe main objective of the present study is to provide a comprehensive image of the expected wind patterns along the 21st century in the Black Sea using the wind fields simulated by Regional Climate Model (RCM), namely Rossby Centre regional atmospheric model (version RCA4). Long‐term averages, long‐term variability, and long‐term trends in wind characteristics over the Black Sea are evaluated in two future time slices (near future 2021–2060 and middle future 2061–2100) under the two climate scenarios (RCP4.5 and 8.5). Detailed analysis of wind (annual mean and 99th percentile wind speeds) and storm characteristics (number and duration of storms) are conducted for three different locations selected on the same meridional section to assess the variability on the wind characteristics from west to east. Spatiotemporal variability on the wind characteristics indicates that the eastern Black Sea will be characterized by lower mean wind speed, stronger 99th percentile wind speed, and higher variability. Considering the global indicators of climate change (e.g., increasing frequency and intensity of extreme events), the eastern Black Sea, characterized by complex atmospheric circulation due to surrounding mountains, is more likely to be subjected to the impacts of climate change as the occurrence of extreme wind speeds in future periods is more prominent in this region. In the future periods, the 100‐year return period wind speeds increase approximately 7% and 27% in the western and eastern Black Sea, respectively, compared to the historical period. The strong and relatively stable winds with low variability in the western Black Sea indicate a reliable, persistent, and sustainable wind energy potential in this region in the future.

FLUID FLOW STUDY IN VARIOUS SHAPES AND SIZES OF HORIZONTAL AXIS SEA CURRENT TURBINE

The ducted tidal turbine models have been developed to utilize the conversion of the kinetic energy on ocean currents. The research in refining the turbine characteristics has been carried out by modifying the turbine’s shape and size. This study investigated flow characteristics in the meridional section of five ducted turbines models for seawater flow with velocity U0 = 1.5 m/s. The ducted turbine design and construction have five different impeller house diameters and fixed inlet and outlet diameters. The potential energy flow theory and experimental data are used to analyze the flow characteristics of the model. The results show that flow velocity in the x-direction at the inlet and outlet cross-section is getting smaller, reducing the impeller house cross section. Each impeller house size reduction increases the flow speed in the impeller house cross-section and also pressure on all other cross-sections tested. In the inlet area, the increased pressure indicates a decrease in speed flow and discharge coefficient value. The discharge coefficient value decreases from CQ = 0.9 at the diameter ratio of dr = 1 to CQ = 0.56 at the diameter ratio of dr = 0.375. The maximum value of power coefficient was determined at dr = 0,61÷0.73 or dr = 0.69 which is equivalent to average internal flow velocity Vr =2.0÷2.6 m/s and the static pressure ps = 97.1÷ 94.4 kPa. At the ratio value of D0/D2 = 0.83, the optimal diameter ratio dropt=0,61÷0.73 is in line with the duct model of case 3 and case 4, but it may be determined solely as for case 4.

The Norwegian Sea Gyre – A Regulator of Iceland-Scotland Ridge Exchanges

The Norwegian Sea gyre (NSG) is a large body of Arctic intermediate water and deep dense overflow waters, which circulate counterclockwise within the Norwegian Sea. Argo float trajectories presented in this study suggest that the NSG attains its strongest and most focused flow downstream of a confluence of subarctic waters from the Iceland Sea and the Jan Mayen Ridge at steep bathymetry north of the Faroe slope. Based on hydrographic data from a meridional standard section across this flow (1988 to present), the first baroclinic estimate of the NSG circulation strength is provided. We, furthermore, show that the NSG circulation regulates key aspects of both the poleward Atlantic Water (AW) currents and the equatorward near-bottom and mid-depth flows in the Norwegian Sea – the main arteries of the Meridional Overturning Circulation. More specifically, we demonstrate close links between the NSG circulation and (i) the observed Faroe Bank Channel Overflow (FBCO) transport, (ii) variable depth of the main thermocline separating AW from the underlying colder and denser subarctic water masses, and (iii) satellite-derived sea-surface heights (SSHs) in the southern Nordic Seas. In general, a strong NSG and weak FBCO transport are associated with an uplifted thermocline and depressed SSH. Along a narrow band near the Norwegian and Shetland slopes, a strong NSG – oppositely – links to a depressed interface. Daily records of the FBCO transport, and satellite altimetry in a sensitive region north of the Iceland-Faroe Ridge, complement our hydrographic monitoring of the NSG strength. Together these records constitute valuable indicators for aspects of the Norwegian Sea physical oceanography, which likely have an impact on regional climate, ecology and biological productivity.

Spatial and Temporal Variability of Diapycnal Mixing in the Indian Ocean

AbstractThe rate of turbulent kinetic energy dissipation and diapycnal diffusivity are estimated along 10 hydrographic sections across the Indian Ocean from a depth of 500 m to the seabed. Six sections were occupied twice. On the meridional section, which is nominally along 95°E, spatial patterns were observed to persist throughout the three occupations. Since the variability in diffusivity exceeds the variability in the vertical gradients of temperature and salinity, we conclude that the diffusive diapycnal fluxes vary mostly with diffusivity. In high latitudes, diapycnal diffusions of both temperature and salinity contribute almost equally to density diffusion, particularly across isopycnals just above the salinity maximum, while mainly temperature contributes in other latitudes. The known zonal difference in turbulence is reproduced. Diffusivity from the seabed to 4,000 m above the seabed has an exponential profile with a mode value of 4 × 10−4 m2s−1 at 1,000 m above the seabed and is positively correlated with topographic roughness as reported previously. It is found that the diffusivity also correlates with wind power injected through the surface at near‐inertial frequencies 10–80 days before the observations. These correlations were used to interpolate the observation‐based turbulence quantities to the entire Indian Ocean. Although the dissipation averaged along selected neutral‐density surfaces is less than the dissipation needed to explain the meridional overturning circulation evaluated across 32°S latitude, this may be explained by effects not captured by the ship‐based observations and parameterization. These effects likely include unobserved high‐mixing events, near bottom processes (e.g., hydraulic jumps), and deep equatorial jets.

Contribution of Gulf of Aqaba Water (GAW) to Red Sea waters

Data obtained on hydrography and currents in meridional sections in the Gulf of Aqaba and the Red Sea in November 2013 and March 2015 were used to determine the extent of contribution of Gulf of Aqaba Water (GAW) to the formation of Red Sea waters. The southward flow across the Strait of Tiran was ~0.02 Sv in both periods which is direct evidence of significant contribution of GAW to Red Sea waters in autumn-winter. A multiple tracer analysis using temperature, salinity, and dissolved oxygen showed that the GAW, on entry into Red Sea, bifurcates into two branches. The upper branch exiting the Strait in the depth range 150-220 m has densities between 28.3 and 28.5, continues to flow at the same depths, and feeds the Red Sea Overflow Water (RSOW). The lower branch that exits between 220 and 250 m above the sill cascades down its southern face, mixes with northward recirculating branch of Red Sea Deep Water (RSDW) and sinks to the bottom and forms part of southward-flowing RSDW. Contribution of GAW to northern Red Sea waters below 100 m depth was 36 ± 0.4% in November 2013 and 42.1 ± 5.4% in March 2015. GAW is traceable down to 17-19 °N in RSDW and RSOW. Volume contribution of GAW to RSOW was 9.6 * 1012 m3, about 50% higher than that for RSDW (6 * 1012 m3). Analyses of the data from R.V. Maurice Ewing cruise in 2001 gave similar results and lend support for these deductions.

Análisis de cambios en los afloramientos en el Pacífico Ecuatorial este, durante eventos El Niño Oscilación del Sur

The ocean reanalysis Simple Ocean Data Assimilation (SODA) 2.2.4 is used to explore the changes in upwelling from normal conditions to either El Niño or La Niña conditions. Physical and thermodynamic variables from the reanalysis are used to explore the structure and behaviour of El Niño Southern Oscillation (ENSO) events. The results of this analysis show that sea surface temperature (SST), entrainment velocity, wind stress, mixedlayer depth, wind stress curl, and heat content anomalies are in general agreement with ENSO theory. Interestingly, the distribution of upwelling based on the entrainment velocity is very patchy, which led us to explore zonal and meridional sections of vertical velocity. We used three methods to compute changes in upwelling during ENSO events. The fi method computes upwelling within the areas of SST anomalies during ENSO events. During El Niño events upwelling shows prominent decadal variability, while during La Niña the decadal variability is weaker. A new upwelling index is used for the second method, and upwelling is computed in the areas of strong upwellinganomalies. The variability of upwelling is higher in periods of reduced upwelling than in periods of strong upwelling. Despite the fact that the new index is computed independently, it agrees in the timing of the index used to define ENSO events for this research. The fi and second methods show that the amplitude of SST anomalies and upwelling anomalies do not have a direct relationship, suggesting that upwelling does not explain all of thevariance in SST. The last method used is to compute changes in upwelling in the Niño 1+2 region during ENSO events. In the east Pacific there is almost no correlation between upwelling and SST anomalies during ENSO, but this might be attributed to the fact that the Niño 1+2 region is a relatively small region compared to the Niño 3.4 region that is used to define ENSO events. In general, the time series of SST and upwelling anomalies agree well just in the cases when ENSO events are prominently in the eastern Pacific.

Structure of a shell made from uranium alloyed with iron and germanium after explosive loading

This paper presents results of metallographic examination of a thick-wall spherical shell from uranium alloyed with iron and germanium. This shell is recovered after low-level explosive loading. Light microscopy, hardness measurement, scanning electron microscopy and X-Ray diffraction study were used to investigate the meridional section of the test shell as this section most completely exhibits the whole variety of structural features associated with explosive loading of the material. Processing, presentation, and analysis of experimental data on volumetric distribution of studied physical quantities were performed with the help of digital panning and color mapping.

Вплив форми кованого однорогого гака на його ефективність

The article analyzes the cargo forged unicorn hook. The design parameters of the product are substantiated by building a solid model of the hook. The line of cargo hooks with the changed form of sections which theoretically allows to reduce weight by 10% at preservation of loading capacity is offered. Comparison of standards shows that at equal loading capacity at identical classes and groups of classification the size and mass characteristics of products differ in times, and not in all cases in favor of standard hooks. Operational tests show that the shape of the hook must ensure its minimum weight with sufficient strength, if possible the same in all sections when the operating conditions and manufacturing technology. It was found that the contours of the upper and lower parts of the cross sections of the hooks are not subject to change. The geometric ratios of the cross-sectional dimensions of the hooks, as well as the threaded part can be considered determined theoretically and experimentally as optimal. Changing the contour is carried out by replacing the rectilinear sides of the trapezoid sections with curved ones. The obtained pictures of stress distribution in the hook body make it possible to choose the path of design optimization in the direction of changing the contours of the equatorial and meridional sections of the fourth quadrant of the hook contour. The proposed change of the contour is carried out by replacing the rectilinear sides of the trapezoidal sections with curved ones. The stress-strain state with visualization and stress distribution is presented, the parameters of the hook are substantiated by building a solid model in the CAD complex Solidworks. The study of the stress distribution pattern made it possible to propose cross-sectional shapes with the subsequent calculation of the stress-strain state of the created model. Material consumption efficiency due to the optimization increases by 10.8% without reducing the load capacity. The changes in the maximum displacement in the proposed model are insignificant (2.55 mm vs. 2.33 mm in the model GOST 2105-75). Recommendations proposed based on the study of one model configuration can be extended to others, taking into account the technology of manufacturing the product.

Parametric modeling method for integrated design and manufacturing of radial compressor impeller

Radial compressor impeller (RCI) manufacturing is moving toward to improve competitiveness through smart manufacturing. Although current CAD (computer-aided design) and CAM (computer-aided manufacturing) techniques provide multiple tools to construct and optimize complicated geometries of RCI, an adjustment of blade shape often leads to nonparametric geometric reconstruction. As the key geometric elements in RCI, set of streamlines (SSL) and meridional section (MS) play vital roles in modeling and aerodynamic optimization. This paper presents a novel approach for automatic extraction of SSL and MS from a RCI 3D model or workpiece. Furthermore, the presented method can interactively construct a parameterized RCI platform, which inputs and outputs the presented RCI parameters to existing CFD and CAM systems rapidly and effectively. An integrated acquisition is employed. The straight generatrix vectors (SGVs) are identified and their boundary points are defined. After the uniform partition of SGV segments, the sequent equant points along spanwise direction are packaged to fit SSL. To manipulate the smoothness and approximation, a double-fitting method is performed to generate SSL. A parameterized system for extracting SSL and modeling RCI is developed. The validities of the presented method in different systems are demonstrated. Furthermore, the presented method breaks conventional RCI development procedure and shortens RCI product cycles, which is desirable and significative for integrated RCI design and manufacturing.

Exploring subtle features of yield surfaces of porous, ductile solids through unit cell simulations

A general computational technique for deriving macro yield surfaces from unit cells with a given microstructure has been proposed in a companion paper (Chouksey, M., Keralavarma, S. M., Basu, S., 2019, “Computational investigation into the role of localization on yield of a porous ductile solid,” Journal of the Mechanics and Physics of Solids, 130,pp. 141–164). Using this technique, macro yield surfaces for porous ductile solids, represented by cuboidal unit cells containing ellipsoidal voids, have been generated and compared with suitable analytical yield criteria. These yield surfaces exhibit vertex-like features when the principal directions of the macro stress coincides with the axes of the ellipsoidal void. In this work, we study the effects of void spacing and orientation with respect to the principal directions nα (α∈[1,3]) of the macro stress. Subtle changes in the yield surface are revealed when its traces are plotted on octahedral or meridional section planes in stress space. Further, the possibility of utilizing the computational framework to automatically generate complete macro yield surfaces by sampling the entire macro stress space, for a given microstructure, is demonstrated with examples where the space of applied macro stress states are limited by suitable assumptions.

Antarctic Bottom Water Warming in the Brazil Basin: 1990s Through 2020, From WOCE to Deep Argo

AbstractA warming trend of 2.1 (±0.4) m °C yr−1 in bottom waters (4,500 to 5,900 dbar) spreading north from Antarctica through the Brazil Basin is quantified by comparing 2019–2020 data from a new Deep Argo regional pilot array to 1989–1995 data from full‐depth zonal and meridional hydrographic sections occupied across the basin before and during the World Ocean Circulation Experiment (WOCE). Additionally, float temperatures are about 0.046°C warmer than those from a long‐term climatology in those same bottom waters. Lower North Atlantic Deep Water in the basin shows no detectable warming, but Upper North Atlantic Deep Water exhibits evidence of warming in both analyses. The bottom‐intensified warming results in a reduction in vertical density stratification between the bottom and deep waters of about 1% per decade. This change is in contrast with the effects of surface‐intensified warming, which tends to increase vertical density stratification.

Hydrodynamic Modeling of Vertical Velocities in the Lofoten Vortex

We analyze high-resolution hydrodynamic modeling data using the Massachusetts Institute of Technology general circulation model (MITgcm), which is a numerical model designed for the study of the atmosphere, ocean, and climate. The focus of the research is the Lofoten Vortex of the Norwegian Sea. We study vertical velocities in the Lofoten Vortex using simulations of MITgcm. The zonal and meridional vertical cross sections of the vertical velocities demonstrate the increase in their values. We also study the seasonal and interannual variability of the vertical velocities in the Lofoten Vortex. The spatial distributions of vertical velocities in the upper layers (e.g. 95 m) of the Lofoten Vortex has a random character in winter (December–April). The values of the vertical velocities have opposite signs in adjacent cells, and vectors of the vertical velocities are directed in opposite directions. However, by summer, an ordered structure is formed that is characteristic of the rest of the year. At the lower horizons (e. g. 1000 m), the distribution of vertical velocities in winter and summer differs insignificantly. We establish that the vortex can be divided into four sectors with alternating directions of the vertical velocities at each horizon. The negative velocities are characteristic of the northeastern and southwestern sectors, with maximum values in the northeastern sector, and positive ones are characteristic of the southeastern and northwestern sectors. An analysis of the Lagrangian particles in the Lofoten Vortex shows that the particles in the upper layers (e. g. 200 m), rotate around the axis of the vortex, and have tendency at the same time to move to the surface, while this tendency is different in the lower layers (1000 m), where the particles can move both to the surface and in the opposite direction. Moreover, for all horizons, the particles, which are initially located in the central part of the vortex, move to the periphery of the vortex as the result of the rotation.

Temperature and chemical species distributions in the middle atmosphere observed during Titan’s late northern spring to early summer

We present a study of the seasonal evolution of Titan’s thermal field and distributions of haze, C2H2, C2H4, C2H6, CH3C2H, C3H8, C4H2, C6H6, HCN, and HC3N from March 2015 (Ls = 66°) to September 2017 (Ls = 93°) (i.e., from the last third of northern spring to early summer). We analyzed thermal emission of Titan’s atmosphere acquired by the Cassini Composite Infrared Spectrometer with limb and nadir geometry to retrieve the stratospheric and mesospheric temperature and mixing ratios pole-to-pole meridional cross sections from 5 mbar to 50 μbar (120–650 km). The southern stratopause varied in a complex way and showed a global temperature increase from 2015 to 2017 at high-southern latitudes. Stratospheric southern polar temperatures, which were observed to be as low as 120 K in early 2015 due to the polar night, showed a 30 K increase (at 0.5 mbar) from March 2015 to May 2017 due to adiabatic heating in the subsiding branch of the global overturning circulation. All photochemical compounds were enriched at the south pole by this subsidence. Polar cross sections of these enhanced species, which are good tracers of the global dynamics, highlighted changes in the structure of the southern polar vortex. These high enhancements combined with the unusually low temperatures (<120 K) of the deep stratosphere resulted in condensation at the south pole between 0.1 and 0.03 mbar (240–280 km) of HCN, HC3N, C6H6 and possibly C4H2 in March 2015 (Ls = 66°). These molecules were observed to condense deeper with increasing distance from the south pole. At high-northern latitudes, stratospheric enrichments remaining from the winter were observed below 300 km between 2015 and May 2017 (Ls = 90°) for all chemical compounds and up to September 2017 (Ls = 93°) for C2H2, C2H4, CH3C2H, C3H8, and C4H2. In September 2017, these local enhancements were less pronounced than earlier for C2H2, C4H2, CH3C2H, HC3N, and HCN, and were no longer observed for C2H6 and C6 H6, which suggests a change in the northern polar dynamics near the summer solstice. These enhancements observed during the entire spring may be due to confinement of this enriched air by a small remaining winter circulation cell that persisted in the low stratosphere up to the northern summer solstice, according to predictions of the Institut Pierre Simon Laplace Titan Global Climate Model (IPSL Titan GCM). In the mesosphere we derived a depleted layer in C2H2, HCN, and C2H6 from the north pole to mid-southern latitudes, while C4H2, C3H4, C2H4, and HC3N seem to have been enriched in the same region. In the deep stratosphere, all molecules except C2H4 were depleted due to their condensation sink located deeper than 5 mbar outside the southern polar vortex. HCN, C4H2, and CH3C2H volume mixing ratio cross section contours showed steep slopes near the mid-latitudes or close to the equator, which can be explained by upwelling air in this region. Upwelling is also supported by the cross section of the C2H4 (the only molecule not condensing among those studied here) volume mixing ratio observed in the northern hemisphere. We derived the zonal wind velocity up to mesospheric levels from the retrieved thermal field. We show that zonal winds were faster and more confined around the south pole in 2015 (Ls = 67−72°) than later. In 2016, the polar zonal wind speed decreased while the fastest winds had migrated toward low-southern latitudes.

Multidecadal Warming and Density Loss in the Deep Weddell Sea, Antarctica

AbstractThe World Ocean is estimated to store more than 90% of the excess energy resulting from man-made greenhouse gas–driven radiative forcing as heat. Uncertainties of this estimate are related to undersampling of the subpolar and polar regions and of the depths below 2000 m. Here we present measurements from the Weddell Sea that cover the whole water column down to the sea floor, taken by the same accurate method at locations revisited every few years since 1989. Our results show widespread warming with similar long-term temperature trends below 700-m depth at all sampling sites. The mean heating rate below 2000 m exceeds that of the global ocean by a factor of about 5. Salinity tends to increase—in contrast to other Southern Ocean regions—at most sites and depths below 700 m, but nowhere strongly enough to fully compensate for the warming effect on seawater density, which hence shows a general decrease. In the top 700 m neither temperature nor salinity shows clear trends. A closer look at the vertical distribution of changes along an approximately zonal and a meridional section across the Weddell Gyre reveals that the strongest vertically coherent warming is observed at the flanks of the gyre over the deep continental slopes and at its northern edge where the gyre connects to the Antarctic Circumpolar Current (ACC). Most likely, the warming of the interior Weddell Sea is driven by changes of the Weddell Gyre strength and its interaction with the ACC.

Temporal and spatial variability of the suspended particulate matter in the Gdansk Deep and Eastern Gotland Basin

The work was carried out in the south-eastern part of the Baltic Sea on the meridional section along the Russian–Polish border during 2015–2018 using the CTD-sounding. The suspended particulate matter samples were taken with the use of ultrafiltration of sea water (0.4 micron filters). The research was focused on identifying the temporal and spatial variability of suspended particulate matter distribution after a series of inflows of the North Sea waters in 2014–2016. The vertical structure of the suspended particulate matter distribution in the south-eastern Baltic, both on a seasonal and interannual scale, contains the main features common for all marine basins, namely increased concentrations of SPM at the sea surface and bottom and an intermediate layer of minimum concentrations located at a depth of 50–70 m. Seasonal fluctuations in the SPM concentration are very significant and are mainly due to the seasonal variation of bioproduction in the surface layer of the sea and the flow of rivers. The confirmation of the barrier role of density boundaries (thermocline and halocline) in sedimentation and geochemical processes has not been obtained.

Evaluation of glaucoma cases with gonioscopy and optical coherence tomography

Glaucoma is the second leading cause of blindness in the adult population of India. Diagnosis and management depends on categorization of Glaucoma into open or closed angle. : To compare the accuracy of Gonioscopy and Anterior Segment Optical Coherence Tomography (ASOCT) in studying the structures of anterior chamber angle of the eye and find out the agreement between them in detecting angle closure. Cross -sectional observational study. The present study is a hospital based cross-sectional study of patients between 20 to 80 years of age with Glaucoma attending the outdoor patient department in a tertiary care government hospital (New civil hospital), Surat. Patients having Corneal Opacity, and anti-Glaucoma surgeries done were excluded. All diagnosed cases of Glaucoma were evaluated by Gonioscopy in the dark with a Goldman 3 mirror lens Gonioscope at high (16x) magnification for static assessment (without indentation). A narrow slit beam, 2mm* 1mm, was cast during Gonioscopy, avoiding direct illumination over the pupil. The angle in each quadrant was graded with the Shaffer grading system. Anterior Segment OCT was done by TOPCON 3D OCT-1 MAESTRO machine. Imaging was performed in dark room conditions. Patients were imaged gazing straight ahead. Imaging of a single meridional section of the Anterior Chamber Angle at superior, inferior, temporal and nasal quadrants were performed. Grading of Anterior Chamber Angles on AS-OCT is termed as Closed if there is no visualization of Scleral Spur and/or any degree of irido-trabecular contact. kappa value, sensitivity & specificity, positive & negative likelihood ratio. Total 50 Glaucoma patients were examined by Gonioscopy and AS OCT. Total number of Angles examined were 400. Total number of Angles closed on Gonioscopy were 136 (34%). Total number of Angles closed on AS OCT were 190 (47.5%). Agreement between Gonioscopy and AS OCT in detecting angle closure in all 4 quadrants was ‘Moderate to Good’ by Kappa Value.

The Distribution of Nickel in the West-Atlantic Ocean, Its Relationship With Phosphate and a Comparison to Cadmium and Zinc

Nickel (Ni) is a bio-essential element required for the growth of phytoplankton. It is the least studied bio-essential element, mainly because surface ocean Ni concentrations are never fully depleted and Ni is not generally considered to be a limiting factor. However, stimulation of growth after Ni addition has been observed in past experiments when seemingly ample ambient dissolved Ni was present, suggesting not all dissolved Ni is bio-available. This study details the distribution of Ni along the GEOTRACES GA02 Atlantic Meridional section. Concentrations of Ni were lowest in the surface ocean and the lowest observed concentration of 1.7 nmol kg(-1) was found in the northern hemisphere (NH). The generally lower surface concentrations in the NH subtropical gyre compared to the southern hemisphere (SH), might be related to a greater Ni uptake by nitrogen fixers that are stimulated by iron (Fe) deposition. The distribution of Ni resembles the distribution of cadmium (Cd) and also features a so called kink (change in the steepness of slope) in the Ni-PO4 relationship. Like for Cd, this is caused by the mixing of Nordic and Antarctic origin water masses. The overall distribution of Ni is driven by mixing with an influence of regional remineralization. This influence of remineralization is, with a maximum remineralization contribution of 13% of the highest observed concentration, smaller than for Cd (30%), but larger than for zinc (Zn; 6%). The uptake pattern in the formation regions of Antarctic origin water masses is suggested to be more similar to Zn than to Cd, however, the surface concentrations of Ni are never fully depleted. This results in a North Atlantic concentration distribution of Ni where the trends of increasing and decreasing concentrations between water masses are similar to those observed for Cd, but the actual concentrations as well as the uptake and remineralization patterns are different between these elements.