Moninya Roughan

UNSW, Australia · School of Mathematics and Statistics

The East Australian Current (EAC) exhibits significant variability across a wide range of spatial and temporal scales, from mesoscale eddies and meanders to seasonal, interannual, and decadal fluctuations in its intensity, pathway, and influence on the continental shelf circulation. Understanding and monitoring this variability is crucial because t...

Ocean observing systems in coastal, shelf and marginal seas collect diverse oceanographic information supporting a wide range of socioeconomic needs, but observations are necessarily sparse in space and/or time due to practical limitations. Ocean analysis and forecast systems capitalize on such observations, producing data-constrained, four-dimensi...

Western Boundary Currents (WBCs) such as the East Australian Current (EAC) are vital for moving heat from low to high latitudes, controlling regional weather and global climate. Previous EAC System studies have provided a general overview of temperature variability and heat transport, but they lacked spatial and seasonal detail. Using a high‐resolu...

We know that extremes in ocean temperature often extend below the surface, and when these extremes occur in shelf seas they can significantly impact ecosystems and fisheries. However, a key knowledge gap exists around the accuracy of model estimates of the ocean’s subsurface structure, particularly in continental shelf regions with complex circulat...

Ocean models must be regularly updated through the assimilation of observations (data assimilation) in order to correctly represent the timing and locations of eddies. Since initial conditions play an important role in the quality of short-term ocean forecasts, an effective data assimilation scheme to produce accurate state estimates is key to impr...

The intensity and frequency of extreme ocean temperature events, such as marine heatwaves (MHWs) and marine cold spells (MCSs), are expected to change as our oceans warm. Little is known about marine extremes in Australian coastal waters, particularly below the surface. Here we introduce a multi-decadal observational record of extreme ocean tempera...

During 2022, extreme rainfall occurred across southeast Australia, making it the wettest year on record. The oceanic impact of extreme rainfall events in normally ‘dry’ regions is not well understood, as their effects are challenging to observe. Here, we use unique multi-platform timeseries and spatial data from 36 autonomous ocean glider missions...

The range‐expansion of tropical herbivores due to ocean warming can profoundly alter temperate reef communities by overgrazing the seaweed forests that underpin them. Such ecological interactions may be mediated by changes to seaweed‐associated microbiota in response to warming, but empirical evidence demonstrating this is rare. We experimentally s...

Western boundary currents (WBCs) adjacent to subtropical continental shelves (STCSs; between ~25° and 35° latitude; Figure 1) transport heat, nutrients, and biota poleward along the western margins of major ocean basins, interacting with the continental margins and influencing their physics and biology. Eddies and meanders along the shelf edge upwe...

Ocean boundary currents are complex and highly variable systems that play key roles in connecting the open and coastal ocean through cross-slope circulation and upwelling of nutrient-rich water. The structure, strength, and variability of boundary currents are associated with a broad range of spatial and temporal scales. For that reason, long-term...

Marine heatwaves are known to cause severe ecosystem damage and therefore have received attention in recent years. However, the focus has tended to be on global (surface) studies, but not coastal waters. Cyclonic eddies are important and underappreciated components in the eddy-dominated western boundary current system, but their impacts on the path...

Ocean models must be regularly updated through the assimilation of observations (data assimilation) in order to correctly represent the timing and locations of eddies. Since initial conditions play an important role in the quality of short-term ocean forecasts, an effective data assimilation scheme to produce accurate state estimates is key to impr...

Information about population connectivity, including the rates and routes of larval transport as well as source-sink dynamics, is important for the sustainable management of harvested species. For marine species whose primary mode of dispersal is transport during the pelagic larval stage, biophysical modelling of larval dispersal represents a valua...

Marine heatwaves are extreme seawater temperature events that can have severe impacts on marine life. The extent of the ecological damage depends not only on the easily observed surface signature but on the marine heatwave structure at depth. However, due to a paucity of in situ sub-surface observations the vertical structure of marine heatwaves is...

The intensity and frequency of extreme ocean temperature events, such as Marine Heatwaves (MHWs) and Marine cold-spells (MCSs), are expected to change as our oceans warm. Little is known about marine extremes in Australian coastal waters, particularly below the surface. Here we introduce a multi-decadal observational record of extreme ocean tempera...

Ocean observations are the foundation of our understanding of ocean processes. Improving these observations has critical implications for our ability to sustainably derive food from the ocean, predict extreme weather events that take a toll on human life, and produce the goods and services that are needed to meet the needs of a vast and growing pop...

Sea surface temperature observations have shown that western boundary currents, such as the East Australian Current (EAC), are warming faster than the global average. However, we know little about coastal temperature trends inshore of these rapidly warming regions, particularly below the surface. In addition to this, warming rates are typically est...

Context Gamay is a coastal waterway of immense social, cultural and ecological value. Since European settlement, it has become a hub for industrialisation and human modification. There is growing desire for ecosystem-level management of urban waterways, but such efforts are often challenged by a lack of integrated knowledge. Aim and methods We syst...

New Zealand is located in the southwest Pacific Ocean and is surrounded by a complex system of boundary currents that vary on a variety of time scales, with important impacts on weather, primary productivity, and fisheries. While various observational and modeling studies have shed light on many of the characteristics of New Zealand's ocean circula...

Understanding the distribution of chlorophyll on the continental shelves adjacent to western boundary currents is important, both from an ecosystem perspective, as well as for their role as a net sink of atmospheric CO2. However, in‐situ observations of chlorophyll in these dynamic regions are rare. Here, using more than a decade of underwater glid...

Frontal eddies form on the shoreward edge of boundary currents, on average at weekly intervals and can last up to several weeks. This duration allows zooplankton production and completion of the larval stage of fish but may be too ephemeral for longer food chains with planktonic predators to establish. Therefore, frontal eddies may provide a suitab...

Western Boundary Currents and the eddies they shed are high priorities for numerical estimation and forecasting due to their economic, ecological and dynamical importance. However, the rapid evolution, complex dynamics and baroclinic structure that is typical of eddies and the relatively sparse sampling in western boundary currents leads to signifi...

Here we present the first open-access long-term 3D hydrodynamic ocean hindcast for the New Zealand ocean estate. The 28-year 5km×5km resolution free-running ocean model configuration was developed under the umbrella of the Moana Project, using the Regional Ocean Modeling System (ROMS) version 3.9. It includes an improved bathymetry, spectral tidal...

Examining eddy-mean flow interactions in western boundary currents (WBCs) is crucial for understanding the mechanisms of mesoscale eddy generation and the role of eddies in the large-scale circulation. However, this analysis is lacking in the East Australian Current (EAC) system. Here we show the detailed three-dimensional structure of the eddy-mea...

Accurate estimates and forecasts of ocean eddies in key regions such as western boundary currents are important for weather and climate, biology, navigation, and search and rescue. The dynamic nature of mesoscale eddies requires data assimilation to produce accurate eddy timings and locations in ocean model simulations. However, data assimilating m...

Sea surface temperature observations have shown that western boundary currents, such as the East Australian Current (EAC), are warming faster than the global average. However, we know little about coastal temperature trends inshore of these rapidly warming regions, particularly below the surface. In addition to this, warming rates are typically est...

Mesoscale eddies drive variability in phytoplankton functional trait composition and primary productivity (PP) relative to adjacent waters. Offshore waters in southeast Australia are subject to substantial mesoscale eddies that form when the East Australian Current (EAC) travels poleward along the coast, forming distinctive habitats in the upper oc...

We systematically reviewed published literature, Traditional Ecological Knowledge and consulted with local scientists to synthesise all published knowledge of Gamay’s (Botany Bay, Sydney) aquatic ecosystem, identifying key knowledge gaps and future research opportunities for this urban waterway.

Marine heatwaves (MHWs) are extreme ocean temperature events that can have wide-ranging and pervasive effects on marine species and ecosystems. However, studies of MHW characteristics and drivers primarily focus on open-ocean environments, rather than the nearshore coastal ocean (<10 km from coast, <50 m depth). This is despite coastal waters susta...

Marine heatwaves can have devastating ecological and economic impacts and understanding what drives their onset is crucial to achieving improved prediction. A key knowledge gap exists around the subsurface structure and temporal evolution of MHW events in continental shelf regions, where impacts are most significant. Here, we use a realistic, high-...

Western boundary currents (WBCs) of the Southern Hemisphere transport heat poleward and are regions of rapid ocean warming. However, the mechanisms responsible for the enhanced warming over the Southern Hemisphere WBC extensions are still debated. Here we show that enhanced eddy generation in the WBC extensions through changes in barotropic and bar...

Understanding how ocean currents affect larval transport is crucial for understanding population connectivity in sessile marine invertebrates whose primary dispersal opportunity occurs during the pelagic larval stage. This study used Lagrangian particle tracking experiments to examine population connectivity in New Zealand green-lipped mussels (Per...

Coastal pelagic ecosystems are highly variable in space and time, with environmental conditions and the distribution of biomass being driven by complex processes operating at multiple scales. The emergent properties of these processes and their interactive effects result in complex and dynamic environmental mosaics referred to as “seascapes”. Mecha...

Larval dispersal and connectivity have important implications for fisheries management , especially for species with life cycles influenced by ocean boundary currents. Giant Mud Crab (Scylla serrata) and Blue Swimmer Crab (Portunus armatus) are two estuarine portunid crabs (Family: Portunidae) that support significant commercial and recreational ha...

Western boundary currents (WBCs) form the narrow, fast-flowing poleward return flows of the great subtropical ocean gyres and are sources of rapidly varying mesoscale eddies. Accurate simulation of the vertical structure, separation latitude, and ocean heat content of WBCs is important for understanding the poleward transport of heat in the global...

Accurate estimates and forecasts of ocean eddies in key regions such as Western Boundary Currents are important for weather and climate, biology, navigation and search and rescue. The dynamic nature of mesoscale eddies requires data assimilation to produce accurate eddy timings and locations in ocean model simulations. However, data assimilating mo...

Cross-shelf transport plays an important role in the heat, salt, and nutrient budgets of the continental shelf. In this study, we quantify cross-shelf volume transport and explore its dynamics within a high-resolution (2.5–6 km) regional ocean model of the East Australian Current (EAC) System, a western boundary current with a high level of mesosca...

Western boundary currents (WBCs), form the narrow, fast-flowing poleward return flows of the great subtropical ocean gyres and are sources of rapidly varying mesoscale eddies. Accurate simulation of the vertical structure, separation latitude, and ocean heat content of WBCs is important for understanding the poleward transport of heat in the global...

Here we present the first open access long term 3D hydrodynamic ocean hindcast for the New Zealand ocean estate. The 28 years 5 km x 5 km resolution free running ocean model configuration was developed under the umbrella of the Moana Project, using the Regional Ocean Model System (ROMS) version 3.9. It includes an improved bathymetry, spectral tida...

Multi-decadal ocean time-series are fundamental baselines for assessing the impacts of environmental change, however, compiling and quality controlling historic data from multiple sources remains challenging. Here we aggregate, document, and release a number of long time-series temperature products and climatologies compiled from data obtained at 4...

Estuarine outflow can have a significant impact on physical and ecological systems in the coastal ocean. Along southeastern Australia, inshore of the East Australian Current, the shelf is narrow, the coastal circulation is advection dominated, and river estuarine outflow tends to be low, hence river plumes have largely been ignored. For these reaso...

Marine heatwaves (MHWs) are extreme warming events that can result in significant damage to marine ecosystems and local economies. The primary drivers of these events have been frequently studied using an upper ocean heat budget. However, various surface mixed layer (SML) depths have been used with little attention paid to the impact of the depth c...

Western Boundary Current (WBC) extensions such as the East Australian Current (EAC) southern extension are warming 2-3 times faster than the global average. However, there are nuances in the spatial and temporal variability of the warming that are not well resolved in climate models. In addition, the physical drivers of ocean heat content (OHC) ext...

The region where the East Australian Current (EAC) separates from the coast is dynamic and the shelf circulation is impacted by the interplay of the western boundary current and its eddy field with the coastal ocean. This interaction can drive upwelling, retention or export. Hence understanding the connection between offshore waters and the inner s...

Plain Language Summary The East Australian Current (EAC) mean flow is typically coherent from ∼27°S–32°S (upstream), but eddies form after it separates from the coast typically at ∼32°S, associated with high eddy variability downstream. However, we know little about what drives changes in the downstream eddies and the correlation with transport ups...

Plain Language Summary Marine heatwaves (MHWs) are extreme ocean warming events that can have devastating ecological impacts on surface and deep ocean communities, yet knowledge of what drives their depth is limited. Here, we identify drivers and characteristics of MHWs on the surface and at depth over the 1985–2014 period in four dynamically diffe...

The OceanGliders program started in 2016 to support active coordination and enhancement of global glider activity. OceanGliders contributes to the international efforts of the Global Ocean Observation System (GOOS) for Climate, Ocean Health, and Operational Services. It brings together marine scientists and engineers operating gliders around the wo...

Ocean data timeseries are vital for a diverse range of stakeholders (ranging from government, to industry, to academia) to underpin research, support decision making, and identify environmental change. However, continuous monitoring and observation of ocean variables is difficult and expensive. Moreover, since oceans are vast, observations are typi...

The UN Decade of Ocean Science for Sustainable Development should establish a Boundary Ocean Observing Network (BOON) for the Global South (GS). The BOON is part of the OceanGlider Program, which is part of the Global Ocean Observing System (GOOS). The BOON is a network of established timeseries transects collecting long-term data sets. Timeseries...

Cyclonic eddies are diverse in their size, age, upwelling and behaviour, which has significant implications for fisheries production and connectivity when they interact with the continental shelf. To ascertain coastal entrainment by eddies, we compared the larval fish community of 2 contrasting cyclonic eddies in 3 depth strata (0-5, 5-50, 50-100 m...

Western boundary currents (WBCs) have intensified and become more eddying in recent decades due to the spin‐up of the ocean gyres, resulting in warmer open ocean temperatures. However, relatively little is known of how WBC intensification will affect temperatures in adjacent continental shelf waters where societal impact is greatest. We use the wel...

Accurate forecasting of ocean currents in dynamic regions remains a critical challenge due to the sparsity of observations in global ocean observing networks and the limited resolution of present‐day regional ocean models. Lately, traditional observing platforms have been complemented by newly available data streams capable of sampling at higher sp...

The Hawkesbury Bioregion located off southeastern Australia (31.5–34.5oS) is a region of highly variable circulation. The region spans the typical separation point of the East Australian Current (EAC), the western boundary current that dominates the flow along the coast of SE Australia. It lies adjacent to a known ocean warming hotspot in the Tasma...

The availability and accessibility of oceanographic data is critical to the sustainability of our oceans into the future. Ocean temperature climatology data products utilizing long time series provide context to ocean warming and allow the identification of anomalous environmental conditions. Here we describe a new methodology to create a daily sub...

Worldwide bivalve aquaculture is expanding rapidly. Simultaneously, there has been a loss of natural bivalve reefs due to anthropogenic activities. As bivalve reefs support several ecosystem functions disproportionate to the area they cover, there is interest in their restoration. The Firth of Thames (FoT) in northern New Zealand once supported den...