Conductivity-temperature-depth Research Articles

Oceanographic dataset collected during the 2021 scientific expedition of the Canadian Coast Guard Ship Amundsen

Abstract. Since 2003, the state-of-the-art Canadian Coast Guard Ship (CCGS) research icebreaker Amundsen has furrowed the Canadian Arctic waters to support novel research endeavors and collect oceanographic data. This paper presents the data acquisition, the processing methods and an overview of the data collected during the 2021 expedition as the ship traveled over 30 000 km during 122 d across the Canadian Arctic Ocean, collecting sea surface, atmospheric and seabed underway measurements. A total of 266 casts of a conductivity, temperature and depth profiler mounted on a Conductivity Temperature Depth rosette (CTD Rosette) were also conducted to monitor the main physical, chemical and biological parameters of the water column. More specifically, the data presented here were collected with the CTD Rosette across historical sampling transects in Davis Strait, the North Water Polynya (NOW) and Cape Bathurst. A 182 km dedicated survey using the Moving Vessel Profiler® (MVP), equipped with CTD, transmissometer, dissolved oxygen, fluorescence and sound velocity sensors, was conducted across Hudson Strait. We also present an overview of the data collected by the underway systems (seabed, thermosalinograph and atmospheric). Such data are essential in understanding the impacts of climate warming on the unique environments of the Canadian Arctic Ocean. Amundsen Science supports and promotes easy access and sharing of such valuable data to the scientific community.

Stratification of Indonesian Throughflow Water and Its Circulation along 125E in the Banggai - Maluku Sea

secondary pathway of Indonesian Throughflow (ITF) that enters from its inflow portal of the northern Maluku Sea is assumed to recirculate in the Banggai - Maluku Sea, where its upper-layer circulation returns into the Pacific and deeper flows continue southward into Seram/Banda Sea via Lifamatola Strait. However, direct observation in this key region is still limited. Here, using direct CTD (Conductivity Temperature Depth) casts and shipboard ADCP (Acoustic Doppler Curent Profiler) measurement datasets from BUDEE (Banggai Upwelling Dynamics and Ecosystem Experiment) cruise in September 2023, we study stratification and structure of ITF water and its circulation in a meridional section along 125E. The results show the water mass stratification of the mixed layer having a depth of 0-75m with a temperature range of 26-29°C, while the thermocline layer has a depth of 28-407m with a temperature range of 23-26°C, and the deep layer has a depth of 407-1000m with a temperature value of 4-12°C. The current pattern of the Banggai Sea Maluku Sea at a depth of 52-400m is more dominantly influenced by non-tidal currents, the influence of tidal currents only covers a depth of 52m less than non-tidal currents.

Glider-Based Microstructure Measurements of Enhanced Diapycnal Mixing along the Continental Slope of the Western Gulf of Mexico

Glider-based microstructure observations combined with ship-based conductivity–temperature–depth profiles were collected on the western part of the Gulf of Mexico (GoM), within the steep continental slope region in November 2017. Dynamical processes associated with bathymetry were observed, and enhanced mixing along the continental slope was detected, with diffusivity values as high as 10 −3 m 2 /s. Recent studies proposed a conceptual model of deep GoM circulation where deep water entering the GoM sinks and fills the deep GoM through the Yucatan Channel. We hypothesize that to retain mass balance, this continuously supplied deep water has to upwell and create intermediate water, which forms the outflow of the GoM, ventilating the deep GoM on time scales of ~100 years. The western GoM has areas with steep continental slopes, where enhanced mixing likely results in the transformation and upwelling of deep water.

Transformation of South Pacific Water Masses in the Halmahera Sea

The Halmahera Sea is part of the eastern entry route of the Indonesian throughflow (ITF) passages. The characteristics and transformation of the South Pacific water masses are presented based on the HYCOM model (Hybrid Coordinate Ocean Model) and direct observations of CTD (Conductivity, Temperature, Depth) acquired during the East Indonesian Expedition in October 2017 using RV Baruna Jaya VIII. This study is aimed at characterizing the typical water masses observed in the Halmahera Sea and tracking the transformation of the South Pacific water masses in the region. The results show that there was an indication of strong vertical mixing of maximum salinity of the South Pacific thermocline water masses, i.e., South Pacific Subtropical Water (SPSW), from ~35.2 PSU at isopycnal 24 – 25 kg m-3 becomes ~34.8 PSU in the Southern Halmahera Strait (around 200 km from the entry passage, the Northern Halmahera Strait), and rapidly decreases from the Southern Halmahera Strait and Obi Strait to become 34.6 PSU in the Maluku Sea. These preliminary findings suggest a strong mixing in the southern Halmahera Strait and Obi Strait.

Hydrographical implications of ship-induced turbulence in stratified waters, studied through field observations and CFD modelling

Ship-related energy pollution has received increasing attention but almost exclusively regarding radiated underwater noise, while the effect of ship-induced turbulence is lacking in the literature. Here we present novel results regarding turbulent wake development, the interaction between ship-induced turbulence and stratification, and discuss the impact of turbulent ship wakes in the surface ocean, in areas with intense ship traffic. The turbulent wake development was studied in situ, using Acoustic Doppler Current Profilers (ADCP) and conductivity, temperature, depth (CTD) observations of stratification, and through computational fluid dynamics (CFD) modelling. Our results show that the turbulent wake interacts with natural hydrography by entraining water from below the pycnocline, and that stratification influences the turbulent wake development by dampening the vertical extent, resulting in the wake water spreading out along the pycnocline rather than at the surface. The depth and intensity of the turbulent wake represent an unnatural occurrence of turbulence in the surface ocean. The ship-induced turbulence can impact local hydrography, nutrient dynamics and increase plankton mortality due to physical disturbance, especially in areas with intense traffic. Therefore, sampling and modelling of e.g., contaminants in shipping lanes need to consider hydrographic conditions, as stratification may alter the depth and spread of the wake, which in turn governs dilution. Finally, the frequent ship traffic in estuarine and coastal areas, calls for consideration of ship-induced turbulence when studying hydrographic processes.

ASSESSMENT OF THREE-DIMENSIONAL BAROCLINIC CIRCULATION MODEL FOR THE MUSI COASTAL AREA

The hydrodynamics of the Musi estuary ecosystem is influenced by the flow of water discharge from the river, tidal circulation within the estuary, and complex bathymetry. Numerical modeling is one of the best ways to explain the characteristics and processes occurring in the estuary. However, the obtained model requires validation to ensure its accuracy despite the complexity added by variability in tidal and bathymetric conditions, making the validation process more challenging. This difficulty can be overcome by using high-resolution data, which provides a refined understanding of the river-to-sea estuary flow and its variability. The validation process involves the use of conductivity-temperature-depth (CTD) instruments and mooring tidal stations. The validated model is considered capable of accurately simulating tidal propagation as it represents the temperature-salinity-density properties within the estuarine environment. The development of this model demonstrates the effective implementation of these parameters within the Musi estuary ecosystem domain. The 3D model simulation is used to consider the vertical discretization in the river-estuary-sea channel, which enhances the representation of temperature-salinity-density in the water column. The obtained results suggest that the 3D-MIKE modeling is well-suited for operational purposes, including the prediction of hydrodynamics and the management of estuarine areas, specifically in the Musi estuary ecosystem.

Multi-Sensor Observations Reveal Large-Amplitude Nonlinear Internal Waves in the Kara Gates, Arctic Ocean

We present multi-sensor measurements from satellites, unmanned aerial vehicle, marine radar, thermal profilers, and repeated conductivity–temperature–depth casts made in the Kara Gates strait connecting the Barents and the Kara Seas during spring tide in August 2021. Analysis of the field data during an 18-h period from four stations provides evidence that a complex sill in the Kara Gates is the site of regular production of intense large-amplitude nonlinear internal waves. Satellite data show a presence of a relatively warm northeastward surface current from the Barents Sea toward the Kara Sea attaining 0.8–0.9 m/s. Triangle-shaped measurements using three thermal profilers revealed pronounced vertical thermocline oscillations up to 40 m associated with propagation of short-period nonlinear internal waves of depression generated by stratified flow passing a system of shallow sills in the strait. The most intense waves were recorded during the ebb tide slackening and reversal when the background flow was predominantly supercritical. Observed internal waves had wavelengths of ~100 m and traveled northeastward with phase speeds of 0.8–0.9 m/s. The total internal wave energy per unit crest length for the largest waves was estimated to be equal to 1.0–1.8 MJ/m.

Upwellings and downwellings on the edge of the Gaspé Current: Observations and processes

The Gaspé Current carries the relatively fresh surface waters of the St. Lawrence estuary along the Gaspé peninsula to the Gulf of St. Lawrence. It presents complex dynamics including the development of meanders. A density front separates the fresher surface waters of the estuary from the saltier surface waters of the gulf. Over the past 40 years, upwellings and downwellings observed on the edge of this front have been the subject of several investigations. Tang (1982) proposed an analytical model featuring a permanent circulation consisting of an upwelling offshore of the front and a downwelling below the front. Using a unique set of in situ observations made with CTD (Conductivity Temperature Depth) profilers and ADCP (Acoustic Doppler Current Profiler) data collected between September 1991 and June 1993, upwellings and downwellings were inferred using a water masses analysis. Even if their presence is predominant (∼ 80% of the total number of sampled transects), they are not a permanent feature over the entire length of the Gaspé Current front, and their positions relative to the front vary. This data set also made it possible to determine via the ω equation that these vertical currents mostly result from frontogenesis and frontolysis (strengthening and weakening of the front). A new method to combine the ω equation with the nonlinear Ekman pumping shows that wind-driven vertical motions were generally weaker and much shallower than those due to frongenesis/frontolysis. This analysis shows that upwellings and downwellings are dependent on favorable conditions leading to the establishment of Gaspé Current instabilities and to frontogenesis or frontolysis.

Two-Step Correction Based on In-Situ Sound Speed Measurements for USBL Precise Real-Time Positioning

The ultra-short baseline (USBL) positioning system has been widely used for autonomous and remotely operated vehicle (ARV) positioning in marine resource surveying and ocean engineering fields due to its flexible installation and portable operation. Errors related to the sound speed are a critical factor limiting the positioning performance. The conventional strategy adopts a fixed sound velocity profile (SVP) to correct the spatial variation, especially in the vertical direction. However, SVP is actually time-varying, and ignoring this kind of variation will lead to a worse estimation of ARVs’coordinates. In this contribution, we propose a two-step sound speed correction method, where, firstly, the deviation due to the acoustic ray bending effect is corrected by the depth-based ray-tracing policy with the fixed SVP. Then, the temporal variation of SVP is considered, and the fixed SVP is adaptively adjusted according to the in situ sound velocity (SV) measurements provided by the conductivity–temperature–depth (CTD) sensor equipped at the ARV. The proposed method is verified by semi-physical simulation and sea-trail dataset in the South China Sea. When compared to the fixed-SVP method, average positioning accuracy with the resilient SVP be improved by 8%, 21%, and 26% in the east, north, and up directions, respectively. The results demonstrate that the proposed method can efficiently improve the adaptability of sound speed observations and deliver better performance in USBL real-time positioning.

Integrated and compact fiber-optic conductivity-temperature-depth (CTD) sensor for marine detection

Integrated and compact fiber-optic conductivity-temperature-depth (CTD) sensor for marine detection

A meta-deep-learning framework for spatio-temporal underwater SSP inversion

Sound speed distribution, represented by a sound speed profile (SSP), is of great significance because the nonuniform distribution of sound speed will cause signal propagation path bending with Snell effect, which brings difficulties in precise underwater localization such as emergency rescue. Compared with conventional SSP measurement methods via the conductivity-temperature-depth (CTD) or sound-velocity profiler (SVP), SSP inversion methods leveraging measured sound field information have better real-time performance, such as matched field process (MFP), compressed sensing (CS) and artificial neural networks (ANN). Due to the difficulty in measuring empirical SSP data, these methods face with over-fitting problem in few-shot learning that decreases the inversion accuracy. To rapidly obtain accurate SSP, we propose a task-driven meta-deep-learning (TDML) framework for spatio-temporal SSP inversion. The common features of SSPs are learned through multiple base learners to accelerate the convergence of the model on new tasks, and the model’s sensitivity to the change of sound field data is enhanced via meta training, so as to weaken the over-fitting effect and improve the inversion accuracy. Experiment results show that fast and accurate SSP inversion can be achieved by the proposed TDML method.

A novel fast response and high precision water temperature sensor based on Fiber Bragg Grating

A novel fast response and high precision water temperature sensor scheme based on gallium alloy sensitivity enhanced Fiber Bragg Grating(FBG) is proposed and experimentally demonstrated. In order to achieve faster temperature response speed of the sensor, a fiber Bragg grating is encapsulated in a single-end sealed metal tube which is filled with liquid gallium alloy. The very high thermal conductivity of the liquid gallium alloy that is filled in the metal tube gives rise to an experimental sensitivity of 30 pm/℃. Thanks to accurate and optimal design of metal tube structure parameters, the sensor exhibits an excellent response speed of 43 ms/℃ in water. Very good linearity between center wavelength of FBG and temperature is also achieved in the experiment. The research result of this paper is especially useful for applications where rapid temperature response and high precision are required at the same time, such as ocean CTD(Conductivity Temperature Depth) measuring equipment, ocean hydrology and underwater submersible.

Temperature and salinity trends in the northern limit of the Canary Current Upwelling System

Thermohaline time series are crucial for detecting and quantifying abiotic changes in the marine environment, and even more so in the present global change scenario. This is particularly relevant for the Ría the Vigo and its adjacent shelf, a highly productive ecosystem at the northern limit of the Canary Current Upwelling System (CanCUS). This study analyses a 34-year time series (1987–2020) of Conductivity-Temperature-Depth (CTD) casts, the longest series available to date in the region. Long-term trends, shifts, and seasonal variability of temperature and salinity were assessed and investigated in relation to regional meteorological variability and basin-scale atmospheric teleconnection indices. Generalized Additive Models (GAM) allowed us to determine that monthly thermohaline variability can be largely explained by regional meteo-climatic variability, mainly upwelling index and river discharge. Trends and shifts in some teleconnection patterns, especially the East Atlantic (EA) pattern, may also be related to both the shift in salinity in 2013 and its long-term decrease below 50 m depth. Despite the current global warming context, no statistically significant trend was observed for either the upwelling index or temperature. The spatial analysis of sea surface temperature trends suggests that our study area has been responding to climate change differently from other surrounding near-shore areas, as the Finisterre Cape or the southern Bay of Biscay. Overall, this study highlights the importance of long-term observations to elucidate the impact of climate change in the northern limit of the CanCUS and encourages caution when extrapolating conclusions from ecosystem studies on a regional scale.

Assessment of RANS Turbulence Models in Prediction of the Hydrothermal Plume in the Longqi Hydrothermal Field

In this paper, the numerical models are selected to simulate the hydrothermal plume based on the water temperature observation data of the Longqi hydrothermal field in the Southwest Indian Ridge (SWIR). Then, the unsteady Reynolds-averaged Navier–Stokes equations are solved to evaluate the performance of the Realizable k-ε (rke) model and the SST k-ω (sst) model in hydrothermal plume simulation. By comparing the calculated results with the Conductivity Temperature Depth (CTD) observation data and the literature results, the difference in prediction performance between the two models is evaluated. Before the numerical simulation, the optimal mesh parameters are determined by considering the grid independence test. The results show that the relative difference of the maximum plume height calculated by the two models is within 5%. Compared with the CTD 05-2, the rke model calculates the root mean square error of the velocity is 0.5081, which is smaller than that of the sst model. In terms of turbulent viscosity, the rke model is in good agreement with reference value in predicting turbulent viscosity. Therefore, the turbulent viscosity distribution calculated by the rke model is more consistent with the plume development process than that calculated by the sst model. In addition, the two models have the same effect on the prediction of turbulent kinetic energy and plume temperature.

The role of the low-salinity, high-nitrate layer as a novel lateral mechanism for nutrient supply into the San Jorge Gulf (Patagonian Shelf) during mid-summer

The San Jorge Gulf (Patagonian Shelf) is productive in the surface layer mainly in three regions during summer associated with small-scale coastal fronts controlled by interaction with islands to the NE, with coastal upwelling to the SW due to the wind, and with the dynamics of the Southern Tidal Front at the gulf mouth. In early February 2014, a time series of the water column characteristics were performed with a Conductivity-Temperature-Depth (CTD)/rosette package and a vessel hull-mounted acoustic Doppler current profiler (ADCP) over two complete semidiurnal cycles in a quasi-fixed location of the San Jorge Gulf mouth in order to evaluate interaction mechanisms between the surface mixed layer and interior layers that condition the distribution of properties. The pycnocline thickness defined by 24.90 kg m−3<σ0< 25.50 kg m−3 is driven by the semidiurnal tide, with a mean modulation of 32.7 m amplitude during a 2.75 m sea-level oscillation (R2 = 0.75). Patchy cores of minimum salinity (SP∼33.10) with high nitrate concentrations (9.9 mmol m−3, on average) were found at the pycnocline centre (38.0 m ± 4.5 m) during the flood as pulses of sub-surface water between consecutive high tides. Also, a high correlation (R2 = 0.88) was found between the thickness of the low-salinity layer (SP< 33.20) and the pycnocline thickness. A clear mode-1 internal tide of semidiurnal frequency was identified during the time series with some non-linear features in the first tidal cycle. As a consequence, a difference in the reversal of the internal tide was seen during both tidal cycles. The water column decreases its stratification when the low-salinity water enters the gulf due to a widening of the pycnocline thickness. At the same time, moderately high nitrate concentrations are observed in the surface mixed layer, suggesting a novel lateral mechanism to maintain the surface chlorophyll layer observed during mid-summer.

Modification of Pacific water in the northern Canadian Arctic

The oceanography of the northern Canadian Arctic Archipelago (CAA) remains poorly studied. Here we present a unique set of conductivity–temperature–depth (CTD) and nitrate profiles collected in a fjord system around Axel Heiberg Island in the northern CAA during April–May 2022. The profiles are examined within the context of upstream observations in the Arctic Ocean and downstream observations in the central CAA, and reveal the origin of water masses and their interactions with ambient water from the continental slope and the nearby tidewater glacier outlet. The subsurface water (~25–180 m depth) is associated with the Pacific water outflow from the Arctic Ocean. The underlying halocline separates Pacific water from a deeper layer of polar water that has interacted with the warm (&amp;gt;0°C) Atlantic water observed below 240 m depth. Pacific water is significantly modified compared to the adjoining Arctic Ocean, as evidenced by the following details. Cold water intrusions from the tidewater glacier create deviations of ~0.25°C in the temperature profile through the subsurface water down to a depth of 140 m. Profiles show no thermal signature of Pacific summer water. Compared to the adjacent Arctic Ocean, the deeper fraction of Pacific-derived water and the Atlantic-modified polar water are warmer, while the underlying Atlantic water is colder. Overall, our results suggest that Pacific and Atlantic water in this area of the northern CAA are modified due to enhanced vertical mixing in a narrow band over the continental slope and shelf off the CAA, and are further modified by interactions with outlet glaciers in the area. This implies that tracing the initial thermohaline signature of the Pacific and Atlantic water flow through the CAA seems to be hardly possible without the use of additional tracers. We also find evidence of geothermal heating near the seafloor, which is not surprising given the observed presence of terrestrial geothermal vents around Axel Heiberg Island, and speculate this heat flux limits ice growth near the glacier terminus.

Annual evolution of the ice–ocean interaction beneath landfast ice in Prydz Bay, East Antarctica

Abstract. High-frequency observations of the ice–ocean interaction and high-precision estimation of the ice–ocean heat exchange are critical to understanding the thermodynamics of the landfast ice mass balance in Antarctica. To investigate the oceanic contribution to the evolution of the landfast ice, an integrated ocean observation system, including an acoustic Doppler velocimeter (ADV), conductivity–temperature–depth (CTD) sensors, and a sea ice mass balance array (SIMBA), was deployed on the landfast ice near the Chinese Zhongshan Station in Prydz Bay, East Antarctica, from April to November 2021. The CTD sensors recorded the ocean temperature and salinity. The ocean temperature experienced a rapid increase in late April, from −1.62 to the maximum of −1.30 ∘C, and then it gradually decreased to −1.75 ∘C in May and remained at this temperature until November. The seawater salinity and density exhibited similar increasing trends during April and May, with mean rates of 0.04 psu d−1 and 0.03 kg m−3 d−1, respectively, which was related to the strong salt rejection caused by freezing of the landfast ice. The ocean current observed by the ADV had mean horizontal and vertical velocities of 9.5 ± 3.9 and 0.2 ± 0.8 cm s−1, respectively. The domain current direction was ESE (120∘)–WSW (240∘), and the domain velocity (79 %) was 5–15 cm s−1. The oceanic heat flux (Fw) estimated using the residual method reached a peak of 41.3 ± 9.8 W m−2 in April, and then it gradually decreased to a stable level of 7.8 ± 2.9 W m−2 from June to October. The Fw values calculated using three different bulk parameterizations exhibited similar trends with different magnitudes due to the uncertainties of the empirical friction velocity. The spectral analysis results suggest that all of the observed ocean variables exhibited a typical half-day period, indicating the strong diurnal influence of the local tidal oscillations. The large-scale sea ice distribution and ocean circulation contributed to the seasonal variations in the ocean variables, revealing the important relationship between the large-scale and local phenomena. The high-frequency and cross-seasonal observations of oceanic variables obtained in this study allow us to deeply investigate their diurnal and seasonal variations and to evaluate their influences on the landfast ice evolution.

El Niño‐Related Stratification Anomalies Over the Continental Slope Off Oregon in Summer 2014 and 2015: The Potential Vorticity Advection Mechanism

AbstractOver the continental slope off Oregon at the US West Coast, at 44.6°N, vertical stratification is found to be anomalously weak in July–August of 2014 and 2015 both in a regional ocean circulation model and conductivity–temperature–depth (CTD) profile observations. To understand the responsible mechanism, we focus on the layer between the isopycnal surfaces σθ = 26.5 and 26.25 kg m−3 that is found between depths 100 and 300 m and represents material properties characteristic of the slope poleward undercurrent and shelf‐slope exchange. This layer thickness, about 50 m on average, can be twice as large during the above‐mentioned periods. In the 2009–2018 model analysis, this anomaly is revealed over the continental slope only in summers 2014 and 2015 and only off the Oregon and Washington coasts (40°–47°N). The stratification anomaly is explained as the effect of advection of the seasonal along‐slope potential vorticity (PV) gradient by an anomalously strong poleward slope current. In the annual cycle, the zone of strong along‐slope PV gradient is found between 40° and 47°N, supported by the local upwelling that results in the injection of the large PV in the bottom boundary layer over the shelf followed by its offshore transport in the slope region. The positive along‐slope current anomaly propagates to Oregon with coastally trapped waves as part of the El Niño oceanic response and can be up to 0.1 m s−1. Advection by this anomalous poleward current results in transporting the seasonal PV gradient earlier in the season than on average.

Sudden, local temperature increase above the continental slope in the southern Weddell Sea, Antarctica

Abstract. Around most of Antarctica, the Circumpolar Deep Water (CDW) shows a warming trend. At the same time, the thermocline is shoaling, thereby increasing the potential for CDW to enter the shallow continental shelves and ultimately increase basal melt in the ice shelf cavities that line the coast. Similar trends, on the order of 0.05 ∘C and 3 m per decade, have been observed in the Warm Deep Water (WDW), the slightly cooled CDW derivative found at depth in the Weddell Sea. Here, we report on a sudden, local increase in the temperature maximum of the WDW above the continental slope north of the Filchner Trough (74∘ S, 25–40∘ W), a region identified as a hotspot for both Antarctic Bottom Water formation (AABW) and potential changes in the flow of WDW towards the large Filchner–Ronne Ice Shelf. New conductivity–temperature–depth profiles, obtained in summer 2021, and recent (2017–2021) mooring records show that the temperature of the warm-water core increased by about 0.1 ∘C over the upper part of the slope (700–2750 m depth) compared with historical (1973–2018) measurements. The temperature increase occurred relatively suddenly in late 2019 and was accompanied by an unprecedented (in observations) freshening of the overlying winter water. The AABW descending down the continental slope from Filchner Trough is sourced by dense ice shelf water and consists to a large degree (60 %) of entrained WDW. The observed temperature increase can hence be expected to imprint directly on deep-water properties, increasing the temperature of newly produced bottom water (by up to 0.06 ∘C) and reducing its density.

Sustained year-round oceanographic measurements from Rothera Research Station, Antarctica, 1997–2017

Oceanographic changes adjacent to Antarctica have global climatic and ecological impacts. However, this is the most challenging place in the world to obtain marine data due to its remoteness and inhospitable nature, especially in winter. Here, we present more than 2000 Conductivity-Temperature-Depth (CTD) profiles and associated water sample data collected with (almost uniquely) full year-round coverage from the British Antarctic Survey Rothera Research Station at the west Antarctic Peninsula. Sampling is conducted from a small boat or a sled, depending on the sea ice conditions. When conditions allow, sampling is twice weekly in summer and weekly in winter, with profiling to nominally 500 m and with discrete water samples taken at 15 m water depth. Daily observations are made of the sea ice conditions in the area. This paper presents the first 20 years of data collection, 1997-2017. This time series represents a unique and valuable resource for investigations of the high-latitude ocean’s role in climate change, ocean/ice interactions, and marine biogeochemistry and carbon drawdown.