Dense Water Research Articles

Spatiotemporal variability of dissolved inorganic macronutrients along the northern Antarctic Peninsula (1996–2019)

AbstractThe northern Antarctic Peninsula is a key region of the Southern Ocean due to its complex ocean dynamics, distinct water mass sources, and the climate‐driven changes taking place in the region. Despite the importance of macronutrients in supporting strong biological carbon uptake and storage, little is known about their spatiotemporal variability along the northern Antarctic Peninsula. Hence, we explored for the first time a 24‐year time series (1996–2019) in this region to understand the processes involved in the spatial and interannual variability of macronutrients. We found high macronutrient concentrations, even in surface waters and during strong phytoplankton blooms. Minimum concentrations of dissolved inorganic nitrogen (DIN; 16 μmol kg−1), phosphate (0.7 μmol kg−1), and silicic acid (40 μmol kg−1) in surface waters are higher than those recorded in surrounding regions. The main source of macronutrients is the intrusions of Circumpolar Deep Water and its modified variety, while local sources (organic matter remineralization, water mass mixing, and mesoscale structures) can enhance their spatiotemporal variability. However, we identified a depletion in silicic acid due to the influence of Dense Shelf Water from the Weddell Sea. Macronutrient concentrations show substantial interannual variability driven by the balance between the intrusions of modified Circumpolar Deep Water and advection of Dense Shelf Water, which is largely modulated by the Southern Annular Mode (SAM) and to some extent by El Niño‐Southern Oscillation (ENSO). These findings are critical to improving our understanding of the natural variability of this Southern Ocean ecosystem and how it is responding to climate changes.

Hunting paleoceanographic archives of ice sheet-ocean interaction in the northwestern Ross Sea, Antarctica

The analysis of sedimentary deposits influenced by bottom currents in glaciated continental margins provides crucial insights into paleo-depositional and oceanographic conditions. These reconstructions enable the assessment of interactions between advance and retreat of grounded ice sheets and past ocean circulation patterns. However, questions regarding these interactions and their specific mechanisms remain largely unanswered due to a lack of data in this remote area. In this study, we conducted a comprehensive analysis by integrating marine geophysical data, surficial sediment cores, oceanographic measurements, and ocean circulation models. Our aim was to understand spatial and temporal variations in sedimentary and oceanographic conditions during the past glacial and interglacial periods in combination with the long-term stratigraphic evolution. By integrating and cross-referencing diverse datasets, we were able to infer how bottom-current-controlled deposits (i.e., contourites) developed along the western bathymetric high of the Central Basin in the northwestern Ross Sea margin, Antarctica. Contouritic deposits lying over and along the flanks of bathymetric highs were identified through their mound-shaped external geometry and acoustically stratified facies, characterized by reflectors pinching toward the moat. Acoustic facies and multi-beam backscatter results, in conjunction with sedimentary core data, revealed contrasting patterns. Bathymetric highs exhibited thin (<10 m thick) coarser-grained sedimentary layers with higher backscatter, while the lower slope and rise displayed thick (>10 m thick), finer-grained stratified sediments with lower backscatter. These findings indicate that seabed winnowing occurred by strong bottom current during past glacial periods as supported by sedimentological analysis. The pathways of the westward-deflected dense shelf water outflow and the westward-flowing along-slope current, as simulated by oceanographic models, explain the distinctive development of contourites influenced by bottom-current processes. Moreover, the large accumulations of sediment in the contourites, resulting from bathymetric barriers in the north of the Central Basin, may contribute to submarine slope failures.

Surface‐Forced Variability in the Nordic Seas Overturning Circulation and Overflows

AbstractWater mass transformation in the Nordic Seas and the associated overflow of dense waters across the Greenland‐Scotland Ridge (GSR) acts to maintain the lower limb of the Atlantic meridional overturning circulation. Here, we use ocean and atmospheric reanalysis to assess the temporal variability in the Nordic Seas overturning circulation between 1950 and 2020 and its relation to surface buoyancy forcing. We find that variable surface‐forced transformation of Atlantic waters in the eastern Nordic Seas can explain variations in overflow transport across the GSR. The production of dense water masses in the Greenland and Iceland Seas is of minor importance to overflow variability. The Nordic Seas overturning circulation shows pronounced multidecadal variability that is in phase with the Atlantic Multidecadal Variability (AMV) index, but no long‐term trend. As the AMV is currently transitioning into its negative phase, the next decades could see a decreased overflow from the Nordic Seas.

Droplet Formation in Dynamic Stratified Liquid–Liquid Systems for Solution-Based Deposition Methods

Abstract The assembly of a two-dimensional (2D) nematic liquid crystal at an interface between two liquids can be exploited to assemble densely packed and highly aligned arrays of rod-like nanoparticles. This method is especially relevant to creating arrays of semiconducting carbon nanotubes (CNTs) for high-performance electronics. When a dense solvent containing CNTs flows over a less dense water subphase in a confined channel, the locally aligned arrays of nanoparticles align globally with the flow direction and can be transferred to the substrate. For large substrates and long channels, the dense solvent tends to slow and create a pool, which then drops through the interface and disturbs the delicate deposition process. Understanding this phenomenon is critical to improving and scaling up similar manufacturing processes. Here, data are collected, and an empirical model is developed to understand and predict the pooling behavior of a suspended fluid flowing over a less dense subphase. The model is demonstrated with two different solvents and proves to be accurate within +/− 15%. With a better understanding of the physics governing the system, the model is then used to suggest methods for minimizing pooling behavior.

Sea Ice Formation, Glacial Melt and the Solubility Pump Boundary Conditions in the Ross Sea

AbstractSeasonal formation of Dense Shelf Water (DSW) in the Ross Sea is a direct precursor to Antarctic Bottom Water, which fills the deep ocean with atmospheric gases in what composes the southern limb of the solubility pump. Measurements of seawater noble gas concentrations during katabatic wind events in two Ross Sea polynyas reveal the physical processes that determine the boundary value properties for DSW. This decomposition reveals 5–6 g kg−1 of glacial meltwater in DSW and sea‐ice production rates of up to 14 m yr−1 within the Terra Nova Bay polynya. Despite winds upwards of 35 m s−1 during the observations, air bubble injection had a minimal contribution to gas exchange, accounting for less than 0.01 μmols kg−1 of argon in seawater. This suggests the slurry of frazil ice and seawater at the polynya surface inhibits air‐sea exchange. Most noteworthy is the revelation that sea‐ice formation and glacial melt contribute significantly to the ventilation of DSW, restoring 10% of the gas deficit for krypton, 24% for argon, and 131% for neon, while diffusive gas exchange contributes the remainder. These measurements reveal a cryogenic component to the solubility pump and demonstrate that while sea ice blocks air‐sea exchange, sea ice formation and glacial melt partially offset this effect via addition of gases. While polynyas are a small surface area, they represent an important ventilation site within the southern‐overturning cell, suggesting that ice processes both enhance and hinder the solubility pump.

Weddell Sea Control of Ocean Temperature Variability on the Western Antarctic Peninsula

AbstractRecent ice loss on the western Antarctic Peninsula has been driven by warming ocean waters on the continental shelf. However, due to the short observational record, our understanding of the dynamics and variability in this region remains poor. High‐resolution ocean model simulations show that the temperature variability along the western Antarctic Peninsula is controlled by the rate of dense water formation in the Weddell Sea. Passive tracer advection reveals connectivity between the Weddell Sea and the coastline of the western Antarctic Peninsula and Bellingshausen Sea. During multi‐year periods of weak Weddell dense water formation, dense overflow transport in the Weddell Sea decreases, while the transport of cold water around the tip of the Antarctic Peninsula strengthens, driving a temperature decrease of 0.4°C along the western Antarctic Peninsula. This mechanism implies that western Antarctic Peninsula coastal ocean temperature may cool in the future if Weddell Dense Shelf Water production slows down.

The role of shallow and deep circulations in the Tropical Pacific Ocean heat budget

The Tropical Pacific Ocean plays an important role in setting the global ocean heat content and redistribution. We examined the role of the shallow and deep circulations in the tropical Pacific in unperturbed and transient climate change conditions in a global ocean model. We found that, in the Control state, the shallow circulation is by far the largest contributor to the overall balance of the column, where the balance is set as the residual between advective cooling and warming by vertical diffusive mixing. Subject to surface flux perturbations, changes in the tropical Pacific ocean heat budget can be explained by shallow wind-driven overturning circulation changes. For wind stress anomalies, the shallow ocean heat budget imbalance is directly related to overturning circulation changes, whereas under heat flux perturbations, warming of the shallow ocean is related to strengthened mid-latitude subduction and weakened dense water production at higher latitudes.

Transport and accumulation of litter in submarine canyons: a geoscience perspective

Marine litter is one of the most pervasive and fast-growing aspects of contamination in the global ocean, and has been observed in every environmental setting, including the deep seafloor where little is known about the magnitude and consequences of the problem. Submarine canyons, the main conduits for the transport of sediment, organic matter and water masses from shallow to abyssal depths, have been claimed to be preferential pathways for litter transport and accumulation in the deep sea. This is supported by ongoing evidence of large litter piles at great water depths, highlighting efficient transfer via canyons. The aim of this article is to present an overview of the current knowledge about marine litter in submarine canyons, taking a geological, process-based point of view. We evaluate sources, transport mechanisms and deposition of litter within canyons to assess the main factors responsible for its transport and accumulation in the deep sea. Few studies relate litter distribution to transport and depositional processes; nevertheless, results from available literature show that canyons represent accumulation areas for both land-based and maritime-based litter. Particularly, accumulation of fishing-related debris is mainly observed at the canyon heads and walls and is related to fishing activities carried out in and adjacent to canyons, while transport and accumulation of general waste and plastic along canyon axes can be related to different mechanisms, encompassing enhanced bottom currents, dense water cascading and turbidity currents, and is related to the proximity of canyons to shore. Global assessment of canyons exposure to riverine plastic inputs and fishing-related debris indicates varying susceptibility of canyons to litter, also highlighting that most of the canyons prone to receive large amounts of anthropogenic debris have not yet been surveyed. Considering that litter research in canyons is still in its infancy, several knowledge gaps need to be filled before the role of canyons as litter traps and the implication for benthic ecosystems can be fully understood.

Restratification in Late Winter Lakes Induced by Cabbeling

AbstractThe under‐ice fluid dynamics during late winter in many freshwater settings remain poorly understood. One example is how cabbeling, the generation of dense water by mixing water masses on different sides of the temperature of maximum density (Tmd), affects the vertical transport. Using high resolution numerical simulations of the development of a stratified parallel shear flow, we show that when the temperature stratification passes through Tmd, cabbeling modifies the three‐dimensional aspects of the instability with the net effect of forming an emergent, stable stratification after a brief period of strong mixing. This stratification effectively separates the quiescent upper layer from the turbulent one below, thereby limiting transport and mixing between them. We propose a simple model for the vertical fluid flux during the mixing regime, and discuss a potential mechanism responsible for the emergent stratification as well as its sensitivity to the bulk Richardson number.

СТРУКТУРА ВОД МОРЕЙ ДЕЙВИСА И МОУСОНА ПО ДАННЫМ ОКЕАНОГРАФИЧЕСКИХ ИССЛЕДОВАНИЙ, ВЫПОЛНЕННЫХ В ХОДЕ 67-й РАЭ

We present the results of oceanographic studies from 64 stations occupied on the slope and shelf in the Davis Sea and the Mawson Sea during the 67th Russian Antarctic Expedition (RAE) from the R/V “Akademik Fedorov” in January–February 2022. The analysis of unique highprecision CTD data and hydrochemical indicators, together with a comparison with the results of previous studies, allowed us to obtain valuable information about the interannual variability of thermohaline characteristics of Antarctic shelf water on the shelf in the central part of the Davis Sea, to determine the structure of water masses on the slope and shelf in the western part of the Davis Sea and the eastern part of the Mawson Sea. Cascading and dense Antarctic shelf water not been recorded during the research. The thermohaline characteristics of Antarctic shelf water recorded in the central part of the Davis Sea in 2001, 2017, 2021 and dense Antarctic shelf water presence in the basins in February 2022 suggest the participation of Davis Sea shelf water in the ventilation of deep waters and suggest an irregular nature of the source of Antarctic bottom waters in the Davis Sea.

Southern Ocean polynyas and dense water formation in a high-resolution, coupled Earth system model

Abstract. Antarctic coastal polynyas produce dense shelf water, a primary source of Antarctic Bottom Water that contributes to the global overturning circulation. This paper investigates Antarctic dense water formation in the high-resolution version of the Energy Exascale Earth System Model (E3SM-HR). The model is able to reproduce the main Antarctic coastal polynyas, although the polynyas are smaller in area compared to observations. E3SM-HR also simulates several occurrences of open-ocean polynyas (OOPs) in the Weddell Sea at a higher rate than what the last 50 years of the satellite sea ice observational record suggests, but similarly to other high-resolution Earth system model simulations. Furthermore, the densest water masses in the model are formed within the OOPs rather than on the continental shelf as is typically observed. Biases related to the lack of dense water formation on the continental shelf are associated with overly strong atmospheric polar easterlies, which lead to a strong Antarctic Slope Front and too little exchange between on- and off-continental shelf water masses. Strong polar easterlies also produce excessive southward Ekman transport, causing a build-up of sea ice over the continental shelf and enhanced ice melting in the summer season. This, in turn, produces water masses on the continental shelf that are overly fresh and less dense relative to observations. Our results indicate that high resolution alone is insufficient for models to properly reproduce Antarctic dense water; the large-scale polar atmospheric circulation around Antarctica must also be accurately simulated.

Deep-Water Dynamics along the 2012–2020 Observations on the Continental Margin of the Southern Adriatic Sea (Mediterranean Sea)

This work presents the results of long-term deep-water observations carried out in the southwestern Adriatic margin. Hydrodynamics and thermohaline measurements were carried out in the last 100 m of the water column using two long-term moorings placed at two different locations along the western sector of the Adriatic continental margin (open slope vs. submarine canyon). The observations, carried out over a period of almost 10 years, made it possible to define the intra- and interannual deep-water dynamics, which are mainly influenced by the passage of cold, dense water. The hydrodynamic field is influenced by seasonal behavior and varies from year to year, with no clear temporal trend or periodicity. Thermohaline properties follow hydrodynamics but also show a climatological trend toward higher temperatures and salinity. The combination and variability of preconditioning factors explains the interannual variability in dense water passage at the mooring sites triggering the formation of dense water in the northern Adriatic. The impulsive nature of the dense water flow, which is difficult to capture with sporadic oceanographic surveys, and its linkage with the large-scale atmospheric circulation make continuous monitoring essential to answer open questions about cascading processes and deep-water dynamics under a global change scenario.

Controls of Topographic Rossby Wave Properties and Downslope Transport in Dense Overflows

Abstract Antarctic Bottom Water is primarily formed via overflows of dense shelf water (DSW) around the Antarctic continental margins. The dynamics of these overflows therefore influence the global abyssal stratification and circulation. Previous studies indicate that dense overflows can be unstable, energizing topographic Rossby waves (TRW) over the continental slope. However, it remains unclear how the wavelength and frequency of the TRWs are related to the properties of the overflowing DSW and other environmental conditions, and how the TRW properties influence the downslope transport of DSW. This study uses idealized high-resolution numerical simulations to investigate the dynamics of overflow-forced TRWs and the associated downslope transport of DSW. It is shown that the propagation of TRWs is constrained by the geostrophic along-slope flow speed of the DSW and by the dynamics of linear plane waves, allowing the wavelength and frequency of the waves to be predicted a priori. The rate of downslope DSW transport depends nonmonotonically on the slope steepness: steep slopes approximately suppress TRW formation, resulting in steady, frictionally dominated DSW descent. For slopes of intermediate steepness, the overflow becomes unstable and generates TRWs, accompanied by interfacial form stresses that drive DSW downslope relatively rapidly. For gentle slopes, the TRWs lead to the formation of coherent eddies that inhibit downslope DSW transport. These findings may explain the variable properties of TRWs observed in oceanic overflows, and they imply that the rate at which DSW descends to the abyssal ocean depends sensitively on the manifestation of TRWs and/or nonlinear eddies over the continental slope.

Dense water formation in the eastern Mediterranean under a global warming scenario

Abstract. Dense water formation in the eastern Mediterranean (EMed) is essential in sustaining the Mediterranean overturning circulation. Changes in the sources of dense water in the EMed point to changes in the circulation and water properties of the Mediterranean Sea. Here we examine with a regional climate system model the changes in the dense water formation in the EMed through the 21st century under the RCP8.5 emission scenario. Our results show a shift in the dominant source of Eastern Mediterranean Deep Water (EMDW) from the Adriatic Sea to the Aegean Sea in the first half of the 21st century. The projected dense water formation is reduced by 75 % for the Adriatic Sea, 84 % for the Aegean Sea, and 83 % for the Levantine Sea by the end of the century. The reduction in the intensity of deep water formation is related to hydrographic changes in surface and intermediate water that strengthen the vertical stratification, hampering vertical mixing and thus convection. Those changes have an impact on the water that flows through the Strait of Sicily to the western Mediterranean and therefore on the whole Mediterranean system.

Analysis of Drinking Water Quality Directly Related to Health at Refill Depots in the South Bekasi Area, Indonesia

Water is a source of life for living things for daily needs. The dense population and limited water sources result in an increase in drinking water that is suitable for consumption. It has encouraged many people to look for alternative sources of drinking water, one of which consumes drinking water from refill depots. The research aims to analyze microbiological and inorganic chemical parameters in several drinking water sources from water depots in the South Bekasi area, Indonesia. Microbiological analysis of drinking water was carried out by identifying types of germs and inorganic chemical analysis using a spectrophotometer. Based on the study's results, three samples of drinking water were detected containing E.coli bacteria, and five samples of drinking water containing Pseudomonas sp. Inorganic chemical analysis shows that all samples contain inorganic chemical compounds (Ar, F, Cr, Cd, NO2, NO3, CN, Se) with concentrations below the maximum levels allowed by Minister of Health Regulation Indonesia.

Hydrological regime of Sahelian small waterbodies from combined Sentinel-2 MSI and Sentinel-3 Synthetic Aperture Radar Altimeter data

Abstract. In the Sahelian semi-arid region, water resources, especially small waterbodies such as ponds, small lakes, and reservoirs in rural areas are of vital importance. However, because of their high number and the scarce in situ monitoring networks, these resources and their spatiotemporal variability are not well known at the regional scale. This study investigates the hydrological regime of 37 small waterbodies, located in Mali, Niger, and Burkina Faso in central Sahel. We propose a method based on remote sensing data only, which consists of combining water height data from Sentinel-3 Synthetic Aperture Radar Altimeter (SRAL) with water area data obtained with the Sentinel-2 MultiSpectral Instrument (MSI) to create a dense water height time series. Water height variations are then compared to the evaporation estimated by the Penman–Monteith method, using ERA5 reanalysis by the European Centre for Medium-Range Weather Forecasts (ECMWF) to infer water regimes during the dry season. Three main regimes stand out, namely a net water loss, mainly resulting from anthropogenic withdrawals, a net water supply occurring after the end of the rainy season through river network or water table exchange, and a balanced behaviour, where water losses during the dry season closely correspond to evaporation rates. Spatial patterns have been identified; in central Burkina Faso, most of the reservoirs show a net dry season water loss, which is explained by frequent irrigation, while reservoirs in northern Burkina Faso, generally show little water loss, indicating that water withdrawal is not significant in this area. Lakes located in the Inner Niger Delta in Mali and connected to the Niger River network generally show an important water supply, particularly at the beginning of the dry season. Lakes in Niger tend to show a weak signal toward water inflow that could be explained by exchange processes with the groundwater. These results show that satellite data are effective at estimating hydrological regimes and the anthropogenic impact on water resources at the large scale, including resources found in small waterbodies.

Selecting and refining suitable methods of developing digital elevation models to represent geomorphic features and characteristics of smaller wetlands in data-scarce environments

Land surface geomorphology plays an important role in water and sediment dispersal processes in wetlands. For wetland practitioners and researchers to engage with these processes in time and space, they require topographic data in order to derive wetland surface gradient, cross-sectional shape and area, surface and subsurface hydrological connectivity, and hydraulic characteristics. A range of data options, with varying spatial resolutions, are available, ranging from free national and global resources (e.g. contour data and global elevation models) to project-specific high-resolution surveys (e.g. Differential Global Positioning Systems (DGPS), Photogrammetry, Light Detection And Ranging (LiDAR)). Due to the scarcity of high-resolution and high-accuracy data, especially in developing countries, data gathering and processing costs can be significant. This paper presents a commentary on a range of topographic data and processing options for a relatively small (~ 40 ha) floodplain wetland in the Eastern Cape, South Africa. It critically reviews the usefulness and shortfalls of various wetland-related applications ranging from gradient calculations to more detailed hydraulic modelling, and the data resolution required for each application. Free, low-resolution, datasets have a limited representation of geomorphology at this scale due to the relatively low-resolution and large vertical error. Field-based surveys (using survey-grade equipment such as a DGPS) have the benefit of providing accurate terrain results in areas with dense vegetation and surface water, while photogrammetry and LiDAR data are useful to represent the higher resolution morphology across the wetland, despite shortcomings regarding the penetration of dense vegetation and surface water. However, combining DGPS data with LiDAR proves to yield the best model for detailed process modelling for wetlands at the local scale.

Interannual variations of heat budget in the lower layer of the eastern Ross Sea shelf and the forcing mechanisms in the Southern Ocean State Estimate

AbstractThe temporal variation of heat budget in the lower layer of the eastern Ross Sea shelf (ERSS) is crucial for understanding the stability of ice shelves in the Ross Sea. In this study, a 6‐year (2005–2010) simulation from the Southern Ocean State Estimate (SOSE) is employed to analyse the interannual variations of heat budget in the lower layer of the ERSS and the controlling mechanisms. The results reveal that the annual change in the heat content of the study region is dominated by the horizontal heat advection term, and only in 2015 the vertical advection and diffusion terms also play an important role. The horizontal advection term is affected by the intrusion of warm circumpolar deep water (CDW) onto the shelf across the northern boundary of the ERSS, the transport of cold dense shelf water (DSW) from the western Ross Sea shelf, and the transport of CDW across the western boundary of the ERSS. The contributions of these physical processes to the change in annual heat content vary between years. The interannual variation of the CDW intrusion is associated with the strength of eddy activity over the slope, and the interannual variation of heat transports associated with DSW is affected by both the extent of DSW on the western shelf and the coastal circulations that affect the eastward spread of DSW.

Seasonal overturning variability in the eastern North Atlantic subpolar gyre: a Lagrangian perspective

Abstract. Both observations and ocean reanalyses show a pronounced seasonality in the strength of the Atlantic meridional overturning circulation (MOC) within the eastern North Atlantic subpolar gyre (eSPG). However, attributing this overturning seasonality to seasonal dense water formation remains challenging owing to the wide distribution of recirculation timescales within the Iceland and Irminger basins. Here, we investigate the nature of seasonal overturning variability using Lagrangian water parcel trajectories initialised across the Overturning in the Subpolar North Atlantic Program (OSNAP) East section within an eddy-permitting ocean sea ice hindcast. By adopting a Lagrangian perspective, we show that the seasonal minimum of the Eulerian overturning at OSNAP East in autumn results from a combination of enhanced stratification and increased southward transport within the upper East Greenland Current. This convergence of southward transport within the MOC upper limb is explained by decreasing water parcel recirculation times in the upper Irminger Sea, consistent with a gyre-scale response to seasonal wind forcing. To account for the diversity of recirculation times within the eSPG, we also quantify the Lagrangian overturning (LMOC) as the total dense water formation along water parcel trajectories. The majority of water parcels, sourced from the central and southern branches of the North Atlantic Current, fail to return to OSNAP East prior to experiencing wintertime diapycnal transformation into the lower limb, and thus they determine the mean strength of the LMOC within the eSPG (8.9 ± 2.2 Sv). The strong seasonality of the LMOC is explained by a small collection of upper-limb water parcels, circulating rapidly (≤ 8.5 months) in the upper Irminger and central Iceland basins, whose along-stream transformation is determined by their month of arrival at OSNAP East.

Wind– and Sea‐Ice–Driven Interannual Variability of Antarctic Bottom Water Formation

AbstractAntarctic Bottom Water (AABW) is a major component of the global overturning circulation, originating around the Antarctic continental margin. In recent decades AABW has both warmed and freshened, but there is also evidence of large interannual variability. The causes of this underlying variability are not yet fully understood, in part due to a lack of ocean and air‐sea‐ice flux measurements in the region. Here, we simulate the formation and export of AABW from 1958 to 2018 using a global, eddying ocean–sea‐ice model in which the four AABW formation regions and transports agree reasonably well with observations. The simulated formation and export of AABW exhibits strong interannual variability which is not correlated between the different formation regions. Reservoirs of very dense waters at depth in the Weddell and Ross Seas following 1–2 years of strong surface water mass transformation can lead to higher AABW export for up to a decade. In Prydz Bay and at the Adélie Coast in contrast, dense water reservoirs do not persist beyond 1 year which we attribute to the narrower shelf extent in the East Antarctic AABW formation regions. The main factor controlling years of high AABW formation are weaker easterly winds, which reduce sea ice import into the AABW formation region, leaving increased areas of open water primed for air‐sea buoyancy loss and convective overturning. Our study highlights the variability of simulated AABW formation in all four formation regions, with potential implications for interpreting trends in observational data using only limited duration and coverage.