Description: Highlights • A new description of sediment phosphorus dynamics was implemented in a 3D-model. • Oxygen consumption affects oxygen penetration in coastal sediments. • Low oxygen concentrations determine the oxygen penetration in deeper water sediments. • More than 80% of the phosphorus loads (1980–2008) are retained in the Baltic Sea. • Phosphorus is released from anoxic sediments and retained in oxic sediments. Abstract The new approach to model the oxygen dependent phosphate release by implementing formulations of the oxygen penetration depths (OPD) and mineral bound inorganic phosphorus pools to the Swedish Coastal and Ocean Biogeochemical model (SCOBI) is described. The phosphorus dynamics and the oxygen concentrations in the Baltic proper sediment are studied during the period 1980–2008 using SCOBI coupled to the 3D-Rossby Centre Ocean model. Model data are compared to observations from monitoring stations and experiments. The impact from oxygen consumption on the determination of the OPD is found to be largest in the coastal zones where also the largest OPD are found. In the deep water the low oxygen concentrations mainly determine the OPD. Highest modelled release rate of phosphate from the sediment is about 59 × 103 t P year− 1 and is found on anoxic sediment at depths between 60–150 m, corresponding to 17% of the Baltic proper total area. The deposition of organic and inorganic phosphorus on sediments with oxic bottom water is larger than the release of phosphorus, about 43 × 103 t P year− 1. For anoxic bottoms the release of total phosphorus during the investigated period is larger than the deposition, about 19 × 103 t P year− 1. In total the net Baltic proper sediment sink is about 23.7 × 103 t P year− 1. The estimated phosphorus sink efficiency of the entire Baltic Sea is on average about 83% during the period.

Description: The bright colouration of the cytoplasm in intertidal rotaliid foraminifera and their particle-gathering activity reliably reveals live specimens in fresh samples, without any fixatives or dyes applied. Using this approach, we demonstrate that live representatives of three rotaliid species, all belonging to the genus Elphidium, were common on intertidal mud and sand beaches. Two species, E. excavatum clavatum and E. albiumbilicatum, lived close to freshwater outflows, whereas E. williamsoni occupied beaches bathed by waters with normal salinity (surface 26–27‰ in the western White Sea). A least 13 species were found alive in the intertidal zone. Among non-calcareous foraminifera, Miliammina fusca, Ammotium cassis and Ovammina opaca were the most numerous.

Description: The Baltic Sea is a marginal sea, located in a highly industrialized region in Central Northern Europe. Saltwater inflows from the North Sea and associated ventilation of the deep exert crucial control on the entire Baltic Sea ecosystem. This study explores the impact of anticipated sea level changes on the dynamics of those inflows. We use a numerical oceanic general circulation model covering both the Baltic and the North Sea. The model successfully retraces the essential ventilation dynamics throughout the period 1961–2007. A suite of idealized experiments suggests that rising sea level is associated with intensified ventilation as saltwater inflows become stronger, longer, and more frequent. Expressed quantitatively as a salinity increase in the deep central Baltic Sea, we find that a sea level rise of 1 m triggers a saltening of more than 1 PSU. This substantial increase in ventilation is the consequence of the increasing cross section in the Danish Straits amplified by a reduction of vertical mixing

Description: We present Nemo-Nordic, a Baltic and North Sea model based on the NEMO ocean engine. Surrounded by highly industrialized countries, the Baltic and North seas and their assets associated with shipping, fishing and tourism are vulnerable to anthropogenic pressure and climate change. Ocean models providing reliable forecasts and enabling climatic studies are important tools for the shipping infrastructure and to get a better understanding of the effects of climate change on the marine ecosystems. Nemo-Nordic is intended to be a tool for both short-term and long-term simulations and to be used for ocean forecasting as well as process and climatic studies. Here, the scientific and technical choices within Nemo-Nordic are introduced, and the reasons behind the design of the model and its domain and the inclusion of the two seas are explained. The model's ability to represent barotropic and baroclinic dynamics, as well as the vertical structure of the water column, is presented. Biases are shown and discussed. The short-term capabilities of the model are presented, especially its capabilities to represent sea level on an hourly timescale with a high degree of accuracy. We also show that the model can represent longer timescales, with a focus on the major Baltic inflows and the variability in deep-water salinity in the Baltic Sea.

Description: Geosciences, Vol. 7, Pages 111: Structure of Volatile Conduits beneath Gorely Volcano (Kamchatka) Revealed by Local Earthquake Tomography Geosciences doi: 10.3390/geosciences7040111 Authors: Pavel Kuznetsov Ivan Koulakov Andrey Jakovlev Ilyas Abkadyrov Evgeny Deev Evgeny Gordeev Sergey Senyukov Sami El Khrepy Nassir Al Arifi Gorely is an active volcano located 75 km from Petropavlovsk-Kamchatsky, Kamchatka. In 2010–2015, it exhibited strong activity expressed by anomalously high gas emission. In 2013–2014, we deployed a temporary network consisting of 20 temporary seismic stations that operated for one year. We selected 333 events with 1613 P-wave and 2421 S-wave arrival times to build the first tomographic model of this volcano. The seismic model was carefully verified using a series of synthetic tests. Our tomographic model provides a mechanism for volatile feeding of Gorely. An unexpected feature of the model was low Vp/Vs ratios; below 1.4 in some parts. One reason for such low Vp/Vs ratios is gas contamination due to magma degassing. In the central part of the model, directly underneath the Gorely crater, we observe a 2.5 km wide and 1.5 km thick seismic anomaly with a very high Vp/Vs ratio of up to 2. This may represent a magma reservoir with a high melt and/or volatile content. The upper limit of this anomaly, 2.5 km below the surface, may indicate the degassing level, which coincides with the most intense seismicity. Below this reservoir, we observe another columnar high Vp/Vs ratio anomaly. This can be interpreted as a conduit bringing magma and fluids from deeper sources.

Description: Representation of the shelf areas in the global ocean model: key study, questions and perspectives The East Siberian Arctic Shelf (ESAS), consisting of the Laptev, East Siberian and Chukchi Seas, represents the shallowest and broadest shelf region of the entire World Ocean. It occupies a little more than 20% of the total area covered by the Arctic Ocean (AO) and represents a critical physical and biochemical gateway for exchange between AO and terrestrial zone with complex oceanographic and biogeochemical regime influenced by both seawaterof Pacific and Atlantic origins. The is a growing need for better quality estimations of circulation and dynamics on the shelf to answer major present and future scientific, ecosystem and societal issues, because of changing climate. It is a complex task as soon as the ESAS represents wide area with variety of regimes and there is still substantial uncertainty in their role and feedbacks with the wider climate system. Making progress on this is largely dependent on the accurate reproducing of the physical environment in the coupled coastal-open ocean system. We would like to propose modeling system that will help to answer questions on the ESAS observed and future trends and dynamics features across time and space scales tracing the signal through the system Estuaries-ESAS-AO in both upscaling and downscaling directions. To reach mentioned goals, we built a coastal branch of the finite volume version of the global sea ice-ocean model FESOM (Danilov et al., 2004; Danilov, 2012; Wang et al., 2014). FESOM is the first model worldwide that provides multi-resolution functionality to large-scale ocean modeling, allowing to bridge the gap between scales. This unique feature is crucial for high efficient coupling, as soon as the exchange zone can be resolved similarly (with the same resolution) by the global and local solutions. Additional strong side of the elaboration of the coastal branch for the existing global model is a possibility to organize flux treatment in a same manner, increasing efficiency of coupling. Danilov, S., Kivman, G., Schröter, J. (2004). A finite-element ocean model: principles and evaluation, Ocean Model., 6, 125–150. Danilov, S. (2012). Two finite-volume unstructured mesh models for large-scale ocean modeling. Ocean Modell., 47, 14–25. Wang, Q., Danilov, S., Sidorenko, D., Timmermann, R., Wekerle, C., Wang, X., Jung, T., and Schröter, J. (2014). The Finite Element Sea Ice-Ocean Model (FESOM) v.1.4: formulation of an ocean general circulation model, Geosci. Model Dev., 7, 663–693.

Description: Rapid frontline retreat and melting of tidewater glaciers along the Antarctic Peninsula cause surface erosion resulting in a washout of suspended particulate matter (SPM) into coastal surface waters. In Potter Cove, a fjord of ~8.5 km2 surface area, meltwater streams transport 23000-39000 tons of eroded sediments per year that disperse into a five meter thick surface layer varying in spatial expansion depending on wind direction and tidal circulation. We addressed the spatial dynamics of the sediment plume in Potter Cove by modelling SPM circulation under different hydrographic scenarios. We applied numerical implementation of the three-dimensional unstructured-mesh model FESOM-C intended for coastal simulations (1). This model is equipped with the high order horizontal advection schemes and rich variety of the vertical turbulence closures based on implemented GOTM turbulence module (2). The model is based on a finite-volume cell-vertex discretization and works on hybrid unstructured meshes composed of triangles and quads. Model performance was validated by available observations. Our results reveal that water transportation due to lower velocity values close to the glacier front; retain the SPM inside the cove, so that this inner-cove area is more strongly impacted by sedimentation.

Description: Species in the brackish and estuarine ecosystems will experience multiple changes in hydrographic variables due to ongoing climate change and nutrient loads. Here, we investigate how a glacial relict species (Saduria entomon), having relatively cold, low salinity biogeographic origin, could be affected by the combined scenarios of climate change and eutrophication. It is an important prey for higher trophic-level species such as cod, and a predator of other benthic animals. We constructed habitat distribution models based occurrence and density of this species across the entire Baltic and estimated the relative importance of different driving variables. We then used two regional coupled ocean-biogeochemical models to investigate the combined impacts of two future climate change and nutrient loads scenarios on its spatial distribution in 2070-2100. According to the scenarios, the Baltic Sea will become warmer and fresher. Our results show that expected changes in salinity and temperature outrank those due to two nutrient-load scenarios (Baltic Sea Action Plan and business as usual) in their effect on S. entomon distribution. The results are relatively similar when using different models with the same scenarios, thereby increasing the confidence of projections. Overall, our models predict a net increase (and local declines) of suitable habitat area, total abundance and biomass for this species, which is probably facilitated by strong osmoregulation ability and tolerance to temperature changes. We emphasize the necessity of considering multiple hydrographic variables when estimating climate change impacts on species living in brackish and estuarine systems.

Description: The long-wave dynamics of the Lombok Strait, which is the most important link of the West Indonesian throughflow connecting the Pacific and Indian Ocean waters, was simulated and analyzed. A feature of the strait is its extremely complex relief, on which water transport creates a field of pronounced vertical velocities, which requires consideration of the nonhydrostatic component of pressure. The work presents a 3-D nonhydrostatic model in curvilinear coordinates, which is verified on a test problem. Particular attention is paid to the method of solving the 3-D elliptical solver for a nonhydrostatic problem in boundary-matched coordinates and a vertical σ level. The difference in transport through the Lombok Strait is determined by the difference in atmospheric pressure over the Pacific and Indian Oceans. Based on the results of the global simulation, the role of these factors in terms of their variability is analyzed, and the value of nonhydrostatic pressure in the dynamics of the Lombok Strait is revealed and evaluated. The vertical dynamics of the Lombok Strait are considered in detail based on hydrostatic and nonhydrostatic approaches.