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This work presents the steps followed in the design and implementation of a marine observatory that provides the current state and forecast of oceanic conditions relevant to the aquaculture sector. Examples of successful implementation of these guidelines are presented in the framework of the EuroSea project (H2020 grant agreement No. 862626) for two aquaculture sites: Deenish Island in Ireland and El Campello in Spain. In-situ essential ocean measurements, remote-sensing observations and modelled forecasts are jointly provided to the aquaculture end users. The process begins with stakeholder interaction to understand their main needs and concerns, followed by software architecture design and development to facilitate data acquisition, post-processing and visualization on an open-access web platform. User input regarding the development of the observatory and web platform content and frequent feedback are of paramount importance during the whole process to ensure that the services offered match the needs of the aquaculture sector. [ABSTRACT FROM AUTHOR]

Clew Bay is an important aquaculture production area in Ireland. In this study, we focused on a high-resolution simulation of the Clew Bay region based on a regional ocean modeling system (ROMS). Freshwater discharges from eight rivers are included in the model and a wetting–drying scheme has been implemented. The Clew Bay model simulation was validated and calibrated with available observations (e.g., acoustic Doppler current profiler (ADCP), vertical salinity and temperature profiles, and a tide gauge) in the geographic area of the model domain. High correlations were found between the model data and observed temperature, salinity and water levels, along with small root mean square errors. This indicates that the model is able to reproduce the oceanographic phenomena in the study area. The Taylor diagram analysis showed a high correlation coefficient (R = 0.99) between the observed bottom temperature in the Inner Bay and Clew Bay model, along with a small centered root mean square error (RMSD = 0.5 °C). High correlation coefficients (R > 0.80) were found between the model and the two ADCPs for the zonal current component. There was a resemblance in structure between the model and the observed salinity profiles, indicating that freshwater was correctly implemented in the model. Moreover, the correlation coefficient between the model and the tidal sea surface height (SSH) was 0.99, with an RMSD of 0.09 m. We discovered that wind direction and speed had a significant impact on the bay's water inflow rate. The model outputs can be used to provide scientists, fishermen, and decision-makers with hydrodynamic information on ocean conditions in the bay. [ABSTRACT FROM AUTHOR]

A new derivation of ray equations is proposed in the framework of a current uniform with depth, differentiating the contributions from the current-induced wave phase speed and wave group velocity. It is useful when substituting higher order expressions for those quantities that account for a sheared current. The new formulation is easy to implement in third-generation spectral wave models even if this task is not performed in the present paper. The numerical vertical integration of the current profile evaluating the current-induced corrections is also studied. We show that a large numerical error can potentially be induced if one uses the vertical resolution normally encountered in ocean modeling. We offer a simple solution to reduce this error and demonstrate its impact on the computation of the current-induced phase speed and wave group corrections using both theoretical and realistic profiles. Discrepancies can induce changes up to 40% of the current-induced speed. We observe these strong discrepancies for large wavenumbers, associated with wind waves, when current effects are the most prevalent. [ABSTRACT FROM AUTHOR]

As part of the Copernicus Marine Environment Monitoring Service (CMEMS), a physical–biogeochemical coupled model system has been developed to monitor and forecast the ocean dynamics and marine ecosystem of the European waters and more specifically on the Iberia–Biscay–Ireland (IBI) area. The CMEMS IBI coupled model covers the north-east Atlantic Ocean from the Canary Islands to Iceland, including the North Sea and the western Mediterranean, with a NEMO-PISCES 1/36 ∘ model application. The coupled system has been providing 7 d weekly ocean forecasts for CMEMS since April 2018. Prior to its operational launch, a pre-operational qualification simulation (2010–2016) has allowed assessing the model's capacity to reproduce the main biogeochemical and ecosystem features of the IBI area. The objective of this paper is then to describe the consistency and skill assessment of the PISCES biogeochemical model using this 7-year qualification simulation. The model results are compared with available satellite estimates as well as in situ observations (ICES, EMODnet and BGC-Argo). The simulation successfully reproduces the spatial distribution and seasonal cycles of oxygen, nutrients, chlorophyll a and net primary production, and confirms that PISCES is suitable at such a resolution and can be used for operational analysis and forecast applications. This model system can be a useful tool to better understand the current state and changes in the marine biogeochemistry of European waters and can also provide key variables for developing indicators to monitor the health of marine ecosystems. These indicators may be of interest to scientists, policy makers, environmental agencies and the general public. [ABSTRACT FROM AUTHOR]

As part of the Copernicus Marine Environment Monitoring Service (CMEMS), an operational ocean forecasting system was developed to monitor the ocean dynamics and marine ecosystems of the European waters; and more specifically on the IBI (Iberia-Biscay-Ireland) area. The CMEMS IBI physical-biogeochemical coupled system covers the North-East Atlantic Ocean from the Canary Islands to Iceland, including the North Sea and the Western Mediterranean, with a NEMO-PISCES 1/36° model application. Since its operational launch in April 2018, this CMEMS IBI system has provided a weekly short-term (7-days) forecast of the ocean dynamics and key biogeochemical variables of the marine ecosystem. The main goal of this paper is to assess the performances of the IBI biogeochemical system, using a 7-year retrospective simulation that spans from 2010 to 2016. The model results are validated with available satellite and in situ observations from the International Council for the Exploration of the Sea (ICES), the European Marine Observation and Data Network (EMODnet) and the Biogeochemical-Argo float network. The simulation successfully reproduces the spatial distribution and seasonal cycles of oxygen, nutrients, chlorophyll-a, and net primary production. This simulation can be a useful tool to better understand the current state and changes in the marine biogeochemistry of European waters. It can also provide key variables for developing indicators to monitor the health of European marine ecosystems. These indicators may be of interest to scientists, policy makers, environmental agencies and the general public. [ABSTRACT FROM AUTHOR]

The recent financial crisis has boosted the popularity of ethical investing, evidence of this being the large number of European investment funds based on corporate social responsibility and the increasing value of the assets they manage. These funds are not developing evenly, their positions varying from country to country. Significant disproportions can be seen between European countries with mature financial markets and the emerging markets in post-Communist countries. A comparative analysis confirms the hypothesis of a major asymmetry in the development of these funds in favor of non-post-Communist countries. This asymmetry can be set down not only to a generally higher level of development of financial markets there but also to a more favorable set of institutional conditions in many of these countries. [ABSTRACT FROM AUTHOR]

A 3D primitive equation coastal ocean model for southwest Ireland, called the Bantry Bay model, was developed and implemented operationally. Validated model outputs have multiple uses. One of the incentives to develop the model was to explore the possible transport pathways that carry harmful algae blooms (HAB) into Bantry Bay. The model is nested offline in a regional North East Atlantic operational model. Surface forcing is taken from the half-degree Global Forecasting System, available at three-hourly intervals. Heat fluxes are calculated from the bulk formulae. Surface freshwater fluxes are obtained from the prescribed rainfall rates and the evaporation rates calculated by the model. Freshwater discharges from five rivers are included in the model. Model validation and the model skill in representing the water level, currents, temperature and salinity in the bay are reported. A scoring system based on the average adjusted relative mean absolute error for the predicted currents was used. An upgrade to a higher score was achieved through the incorporation of local winds into the surface forcing and by varying the bottom roughness coefficient. The model, designed to work in forecast mode, can replicate the main oceanographic features in the region. The model forecast is used in a decision support system for HAB alerts. An operational HAB alert system did not exist in Ireland prior to the use of this model. [ABSTRACT FROM AUTHOR]

This study investigated the application of a three-dimensional physical hydrodynamic model in a harmful algal bloom forecast system for Bantry Bay, southwest Ireland. Modelled oceanographic conditions were studied and used to help understand observed changes in the chemical and biological patterns from the national biotoxins and phytoplankton monitoring program. The study focused on two toxic events in 2013. An upwelling event was predicted by the model prior to the appearance and population increase of potentially toxic diatoms, Pseudo-nitzschia , and associated domoic acid in shellfish. A downwelling episode was provided as a forecast in the model prior to the arrival of a Dinophysis bloom and detection of its associated biotoxins in Bay shellfish. The modelled forecast products developed included expected surface, mid-depth and bottom current pathways at the mouth of the Bay and on the adjacent shelf. The rate and direction of water volume flow at the mouth and mid-bay sections were produced by the model to examine predicted upwelling and downwelling pulses. The model also calculated the evolution of water properties (temperature, salinity and density) with depth along the Bay axis and on the adjacent continental shelf. Direct measurements of water properties at a fixed point, mid-bay, were comparable to model calculations. The operational model for southwest Ireland produces a reliable 3-day physical hydrodynamic forecast of the dominant regional physical processes that result in water exchange events between Bantry Bay and its adjacent shelf. While simulated physical hydrodynamics were provided as a 3-day forecast, the upwelling and downwelling signals from the model, closely linked to toxic HAB episodes, were evident up to 10 days prior to the contamination of shellfish in the Bay. [ABSTRACT FROM AUTHOR]

Abstract: Bivalve shellfish such as oysters and mussels can concentrate human pathogens when grown in areas impacted by municipal wastewater. Under EU regulation this risk to consumers is controlled by determining the sanitary quality of bivalve shellfish production areas based on the concentration of Escherichia coli present in shellfish flesh. The authors present a modelling approach to simulate an uptake of E. coli from seawater and subsequent depuration by Mytilus edulis. The model that dynamically predicts E. coli concentration in the mussel tissue is embedded within a 3-D numerical modelling system comprising hydrodynamic, biogeochemical, shellfish ecophysiological and the newly proposed microbial modules. The microbial module has two state variables, namely, the concentrations of E. coli in water and in the mussel tissue. Novel formulations to calculate the filtration rates by mussels and the resulting uptake of bacteria are proposed; these rates are updated at every computational time step. Concentrations of E. coli in seawater are also updated accordingly taking into account the amounts ingested by mussels. The model has been applied to Bantry Bay in the south-west of Ireland. The results indicate that the model is capable of reproducing the official classification of shellfish waters in the bay based on monthly sampling at several stations. The predicted filtration rates and ratios of E. coli in water and mussels also compare well with the literature. The model thus forms a tool that may be used to assist in the classification of shellfish waters at much greater spatial and temporal detail than that offered by a field monitoring programme. Moreover, it can also aid in designing an efficient monitoring programme. The model can also be utilised to determine the contribution of individual point sources of pollution on the microbial loading in mussels and, when incorporated into an operational framework, it can provide a short-term forecasting of microbial contamination in a shellfishery. Also, the model can be easily extended to include other shellfish and pathogen species. [Copyright &y& Elsevier]

Abstract: This paper presents a high resolution operational biogeochemical model of the North-East Atlantic that encompasses part of the continental shelf and adjacent deep sea and includes all of Ireland's territorial waters. The setup of the model is described, followed by its skill assessment in reproducing chlorophyll and nitrate spatio-temporal variability. Part of the model skill assessment concerns the evaluation of its usefulness in a decision-making process and is based on the application of a binary discrimination analysis. The model is one-way nested within a 1/12° Mercator Ocean PSY2V4R2 operational model that provides physical forcing at the lateral open boundaries. Nitrate fields are also proscribed at the open boundaries; the World Ocean Atlas 2009 monthly climatologies are used in the upper 500m and at greater depths a formula that relates nitrate concentration to temperature and latitude is applied in the model. The model represents the intra-annual variability of surface chlorophyll and nitrate concentrations at monthly time scales across key oceanographic regions reasonably well; deficiencies are identified in some regions along with possible causes. The model can reproduce important characteristic bio-physicochemical features e.g. the frontal dynamics and upwelling off southwest Ireland and the properties of different water masses in the Rockall Trough. The model is deemed suitable for operational purposes, with a high probability to make correct positive and negative decisions. Operational since 2011, the output is publicly available via a dedicated THREDDS server. [Copyright &y& Elsevier]

Abstract: An assessment of the complex evolution of climate change signals in the Irish Sea over the 21st century is presented in this paper. Potential impacts of climate change on the local hydrography are explored and interrelationships between fundamental oceanographic shelf sea phenomena investigated. A regional ECOMSED ocean model is used to downscale a 120-year period (1980–2099) of the SRES A1B scenario experiment from a global ocean model. A detailed regional analysis shows that local climate changes may be significantly different from the expected global changes. This research suggests that in the future the Irish Sea will be warmer with sea surface temperature increase of around 1.9°C. Maxima and minima annual temperatures will occur around 2 weeks later each year relative to the present climate. Geographically, shallow waters along the coastline and in the eastern Irish Sea will exhibit strongest warming due to increased heat uptake during summer and autumn and reduced heat loss in spring and winter. Warming in the deep channel in the western Irish Sea will be generally weaker with seasonal variability subdued due to a large heat storage capacity. The warming will be largely stored in the surface layer of the water column leading to strengthening of stratification and a considerable decrease in the thickness of the mixed layer. The western Irish Sea gyre will become stronger and result in substantial reinforcement (>30%) of southward currents along the east coast of Ireland. Net northward flow in future predicted climate conditions will be maintained at the current annual rate. Steric sea level is projected to rise by 0.31m during the 21st century, leading to an overall projected sea level rise of approximately of 0.47m. Future changes to oceanographic parameters, flushing times and hydrodynamics of the Irish Sea are likely to alter the habitat and distribution of marine species; the finding of this research are therefore of great interest to ecologists and the fishery industry. [Copyright &y& Elsevier]

Ambitious goals set for all EU states in the water framework directive call for the development of appropriate tools that support the implementation of the directive. Mathematical modelling can be utilised for devising the methodologies that address its many aspects, from evaluation of management alternatives to design of operational monitoring programmes. A major difficulty is the lack of detail in the directive regarding the implementation of monitoring programmes. This paper reviews and discusses the role of modelling in the implementation of the directive, with particular emphasis on integration of modelling into directive monitoring systems. New approaches, such as the Bayesian maximum entropy method, are discussed. The method utilises models in the processes of waterbody mapping and assessment and optimisation of water quality monitoring programmes; the authors are currently implementing the method to Irish coastal waterbodies. It is concluded that one of the main difficulties in implementing the directive is the lack of a structured approach in the development and management of monitoring programmes; mathematical models are recommended tools to help overcome these difficulties. [ABSTRACT FROM AUTHOR]

Flushing is a property of each coastal waterbody and is most often described by a timescale characteristic. A number of techniques have been developed to estimate residence times, but some are overly simplistic and not very accurate, while others are difficult to apply due to data requirements. The main objective of this study is the development of a simplified formula relating flushing characteristics to physical properties of tidally flushed estuaries. Numerical models of several dissimilar estuaries were developed and the modelling results were then used to compute average residence times for the waterbodies. Stepwise linear regression was applied to develop relationships between basic physical properties of the estuaries and the computed average residence times. For tidally flushed estuaries, analysis shows that a statistically high correlation exists between average residence times and combined physical properties of the waterbodies. This paper also compares a newly developed residence time formula with other widely used methods. The new method predicts more accurate estimates of average residence times than the tidal prism models frequently used by researchers. It also compares favourably with complex methods such as the jet-sink circulation model and a method based on salinity. [ABSTRACT FROM AUTHOR]

The primary objective of this research was to develop a generic methodology for numerical modelling of the water quality within estuarine systems; in particular, this research focused on modelling nutrient dynamics and phytoplankton growth. This paper presents details of the developed modelling methodology and its application to Cork Harbour, an Irish waterbody that regularly experiences algal blooms. Input data requirements and, in particular, an innovative method for the determination of spatially varying initial conditions are presented. Phytoplankton dynamics are highly dependent on light intensity; a novel formulation for the light intensity component of the phytoplankton growth module was therefore developed and implemented in the model. The formula, which relates light intensity to turbidity and chlorophyll-a concentrations based on field data, is shown to achieve good results. Phytoplankton predictions were validated in an unusual but very effective manner using remote sensing techniques. A flushing module was included in the model to provide insights into transport processes. The paper demonstrates how simple flushing models may be used as a more cost-effective alternative to full water quality models for identification of potential eutrophic waters. Results from the Cork Harbour model are used throughout to demonstrate the effectiveness of the modelling methodology. [ABSTRACT FROM AUTHOR]

The implementation of the European Union Water Framework Directive (WFD) that requires all surface waters to achieve at least good status by year 2015 presents a challenge to local authorities responsible for the monitoring programmes. Obtaining a single representative value for each water quality parameter may be extremely difficult to achieve in the case of large lakes, which may be characterised by significant spatial and temporal variation of water quality parameters. The aim of this paper is to present a methodology, which can support the decision making as to the best locations for water quality sampling when developing monitoring systems of large lakes. The methodology is based on three-dimensional hydrodynamic and a conservative tracer transport numerical modelling and utilises the concept of flushing and residence time. The 3D numerical model of Lough Corrib located in the west of Ireland was created and used to calculate its residence time and flushing pathways. Based on the results it was possible to identify the areas in the lake that are characterised by the local residence time values close to the lake's average as well as by the values significantly lower and higher. Three water classes have been introduced and the authors recommend that sampling takes place in all three classes at various frequencies. Spatial distribution of the flushing pathways allows identifying the areas in the lake that best represent the lake's average conditions both in the long term and seasonally, where monitoring can be carried out at the required frequency; worst affected areas can also be identified. The methodology can be used to improve robustness of the monitoring programme and may also contribute towards the reduction of both sampling and analytical costs, both at the design and operational stages. [Copyright &y& Elsevier]

An operational model for an area of the northeast Atlantic that encompasses all of Ireland's territorial waters has been developed. The model is an implementation of the Regional Ocean Modelling System (ROMS) and uses operationally available atmospheric and boundary forcing, and a global tide solution for tidal forcing. River forcing is provided by climatological daily discharge rates for 29 rivers across Ireland, west Britain, and west France. It is run in an operational framework to produce 7-day hindcasts once a week, and daily 3-day forecasts which are published in a number of formats. We evaluated the model skill by comparing with measured data and calculating statistics such as mean error, root mean square error (RMSE), and correlation coefficient. The observations consist of satellite Sea Surface Temperature (SST), total surface velocity fields from satellite, water level time series from around the Irish coast, and temperature and salinity data from Array for Real-Time Geostrophic Oceanography (ARGO) and Conductivity Temperature Depth (CTD) profiles. The validation period is from 1 January 2016 until 31 December 2019. The correlation coefficient between the model and satellite SST is 0.97 and recorded in March and April 2018. The model error is about 5% of the total M2 amplitude in the Celtic Sea recorded at Dunmore East tide gauge station. The maximum RMSE between the model and the CTD temperature profiles is 0.8 °C while it is 0.17 PSU for salinity. The model correctly defines the shelf water masses around Ireland. In 2019 the Irish Coastal Current (ICC) was very strong and well defined along most of the western Irish coast. The model results have well reproduced the ICC front for the whole simulation period. [ABSTRACT FROM AUTHOR]

This paper is concerned with solid waste utilization in the specially made for this purpose Pyrolytic Convective Waste Utilizer (PCWU) ofWPS Type, a technology which may be in essential way helpful in getting rid of very noxious wastes. A family of the PCWU WPS utilizers ispresented dependent on the amount of wastes and operation capacitiesrequired. The discussed PCWU WPS Type utilizer was tested in severalareas of Poland by different users, taking into account different sorts of difficult-to-utilize and noxious wastes. The paper, presents structural composition, principal of operation of the PCWU WPS utilizer and then aims at analyzing flue gases and eluates coming from the pyrolytic rendering waste harmless. The primary studies were carried out to determine the most important indicators of pollution in the eluate flowing out of the waste layer after pyrolytic decomposition on the samples taken from the WPS Type Utilizer operating near Gdansk andat Tczew. The comparative study of secondary wastes obtained after thermal decomposition without oxygen access is presented. The detailedstudy results of utilization and neutralization of secondary wastes coming from the WPS Type Utilizer are also included. The studies covered three groups of secondary wastes after pyrolysis process and theywere: (i) acrylic paint wastes, (ii) phtalic paint wastes, and (iii)plastics wastes. The studies were carried out in three stages: 1- covering the studies of eluate outflowing from the layer of secondary wastes; 2- covering the studies of compression strength of cobble-stones manufactured, and 3- covering the studies of water extracts from cobble-stones. In the paper, the authors present comparative direct cost analysis of thermal waste liquidation using classical method in comparison with pyrolytic method. The paper delivers also the authors' own evaluation of the Pyrolytic Convective Waste Utilizer of WPS Typewith indication of the possibility for its broader application. [ABSTRACT FROM AUTHOR]

Abstract: The western Irish Sea gyre (WISG) is a cyclonic baroclinic flow around a dome of stagnant water which develops each year during the heating season in the western Irish Sea. Research was carried out to determine long-term changes in the strength of stratification within WISG and associated changes in the gyre structure, circulation patterns and retentive properties. Model simulations were carried out for the 58-year period 1951–2008. The characteristics of the gyre were quantified by means of potential energy anomaly (PEA), measuring the strength of stratification, and total kinetic energy (KE), reflecting the strength of cyclonic circulation. Additionally, long-term changes in flushing rates within the gyre were assessed. Results show that stratification in the western Irish Sea consistently begins to develop in March, increases linearly from April till June, peaks at the beginning of July and remains at close to maximum level throughout the month of July, before a start of a sharp decline at the beginning of August. The strength of stratification is significantly correlated with averaged summer air temperatures and summer wind speeds. Trend analysis of PEA shows an increase in the stratification strength over the period considered; the increase of PEA peak value is accompanied by a shortening of the gyre duration and a delay in the timing of the peak value. There is also an increasing trend in the KE value, showing that the thermal stratification plays a crucial role in the hydrography of the region. Flushing analysis shows that the stronger the stratification the lower the residence time and thus the faster the removal of the material from the western Irish Sea. Residence time within WISG shortens on average by 8 days over the 58-year period. [Copyright &y& Elsevier]

Abstract: The increased discharge of Tc-99 from the Sellafield plant following the commissioning of the Enhance Actinide Removal Plant in 1994 was reflected in higher Tc-99 activity concentrations over much of the Irish Sea. The presence of this radionuclide in the marine environment is of concern not only because of its long half life but also high bio-concentration factor in commercially valuable species, such Norway lobster (Nephrops norvegicus) and common lobster (Homarus gammarus). Accurate predictions of the transport, and spatial and temporal distributions of Tc-99 in the Irish Sea have important environmental and commercial implications. In this study, transport of the Tc-99 material was simulated in order to develop an increased understanding of long-term horizontal and vertical distributions. In particular, impact of seasonal hydrodynamic features such as the summer stratification on the surface-to-bottom Tc-99 ratio was of interest. Also, material retention mechanisms within the western Irish Sea were explored and flushing rates under various release conditions and meteorological forcing were estimated. The results show that highest vertical gradients are observed between June and July in the deepest regions of the North Channel and the western Irish Sea where radionuclide-rich saline-poor water overlays radionuclide-poor saline-rich Atlantic water masses. Strong correlation between top-to-bottom ratio of Tc-99 and strength of stratification was found. Flushing studies demonstrate that as the stratification intensifies, residence times within the western Irish Sea increase. In stratified waters of the gyre Tc-99 material is flushed out from the upper layer much quicker than from the bottom zone. The research also shows that in the gyre the biologically active upper layers above the thermocline are likely to contain higher concentrations than the near-bed region. Long-term horizontal and vertical distributions as determined in this study provide a basis for assessment of a potential biota exposure to Tc-99. [Copyright &y& Elsevier]

Abstract: Water circulation patterns and associated material transport within a highly dynamic system such as the Irish Sea are complex phenomena. Although Tc-99 monitoring programme undertaken by the Radiological Protection Institute of Ireland provides a good insight to the material distribution on the east coast of Ireland, transport patterns within the Irish Sea have not been fully explored. In this study a validated transport model was used to hindcast transport of Tc-99 discharged from the Sellafield plant to determine extents of Tc-99 migration within the Irish Sea and reassess transit times to east coast of Ireland. Transit times are also estimated within a context of changes in meteorological conditions and fluctuations in discharges. Additionally, seasonal and inter-annual circulation patterns were examined. Relationships between discharge times and timing of far field concentrations are highly variable and are dependant on sea dynamics controlling the accumulation and removal of Tc-99 mass. Transport towards the Irish east coast, and consequently transit times, vary intra- and inter-annually, and depend on the prevailing hydrodynamic conditions resulting from meteorological conditions. The transit times from Sellafield to Balbriggan fall within the wide range of 30–240days; with summer releases resulting in the shortest transit times. The model also indicated a strong relationship between summer concentration peaks on the east coast of Ireland and the strength of the Western Irish Gyre. Sudden increases of Tc-99 concentrations at Balbriggan coincide with peak of sea surface temperatures when the gyre is strongest and when advection is fastest. The adequacy of the current radionuclide monitoring programme within the western Irish Sea is evaluated, and recommendations are made for the development of a more optimised monitoring programme. [Copyright &y& Elsevier]

- Study presents a high resolution 3-D ocean model for southwest Irish waters. - Irish climate model projected RCP simulations (SW_IRL_ROMS_RCPs). - Freshening observed in RCPs scenarios SSS. - Information should help biologists to understand the physical drivers of HABs in the study region. This ocean numerical modelling study is focused on the shelf waters off southwest Ireland. Outputs from the model are used to provide scientists and policy makers with climate change information related to oceanic conditions that influence harmful algal blooms in the region. Four simulations were developed to include a 20-year hindcast simulation (1997–2016), a 31-year historical simulation (1975–2005), and two 30-year future climate model projections (2006–2035) for the representative carbon pathways (RCP) 4.5 and 8.5 scenarios. We evaluated the hindcast model skill by comparing the simulation outputs with measured observational data and calculated statistics such as the bias, and the root mean square error (RMSE). The observations consisted of satellite sea surface temperature and, CTD temperature and salinity profile data collected in Irish waters. The sea surface temperature RMSEs between the 20-year hindcast simulation and the satellite data were ca. 0.50°C. A minimum RMSE of ca. 0.20°C was recorded in December 2015. The basin-averaged bias (difference) and RMSE for near bottom temperature between the RCP 4.5 and the historical simulation was 0.14°C and 0.27°C respectively. The sea surface temperature anomaly pattern for the RCP 8.5 shows warming across the whole model domain. The sea surface salinity and near bottom salinity climate simulation anomaly maps indicate a general freshening on the southwest Irish shelf. A change of ca. 0.2 sea surface salinity and near bottom salinity was observed. The RCP 8.5 simulation shows the highest current velocities when compared to other simulations. The Irish coastal current pattern under the RCP 8.5 scenario appears very intense and well defined with a velocity > 20 [cm/s]. [ABSTRACT FROM AUTHOR]