scholarly journals An Evaluation and Implementation of the Regional Coupled Ice-Ocean Model of the Baltic Sea

2017 ◽  
Author(s):  
Jaromir Jakacki ◽  
Sebastian Meler

Abstract. A three dimensional, regional coupled ice-ocean model based on the open-source Community Earth System Model has been developed and implemented for the Baltic Sea. The model consists of 66 vertical levels and has a horizontal resolution of approx. 2.3 km. The paper focuses on sea ice component results but the main changes have been introduced in the ocean part of the coupled model. The hydrodynamic part, being one of the most important components, has been also presented and validated. The ice model results were validated against the radar and satellite data, and the method of validation based on probability was introduced. In the last two decades satellite and model results show an increase in the ice extent over the whole Baltic Sea, which is an evidence of a negative trend in air temperature in recent decades and increasing of winter discharge from the catchment area.

Author(s):  
Halina Kowalewska-Kalkowska ◽  
Marek Kowalewski

Modeling water exchange in the Oder River mouth areaA three-dimensional operational hydrodynamic model of the Baltic Sea (M3D_UG) developed based on the Princeton Ocean Model (POM) was applied to model water exchange in the Oder River mouth area. Due to wind-driven back flow in the Oder mouth, a simplified operational model of river discharge was also developed based on the water budget in a stream channel. Linking the Oder discharge and Baltic Sea models into a single system allowed simulating hydrodynamic conditions in the Szczecin Lagoon and the Pomeranian Bay. Since the model adequately approximates hydrodynamic variability, it is a reliable tool for modeling water exchange in the Oder River mouth area and for assessing Oder water spread in the Baltic Sea.


Differences and similarities in the way marine and continental organisms occupy space are briefly reviewed. Among them, the ‘peninsula effect’ (the decline of species richness with distance from the source) is compared with the ‘bay effect’. Two cases, corals in Mochima Bay, Venezuela and fishes in the Baltic Sea, are presented as examples. The facts that the world’s oceans are larger, continuous and three-dimensional, with fewer evident geographical barriers than there are on land, explain why marine biogeographical regions are less welldefined and geographical ranges of marine taxa more wide-spread. I his generalization has, however, been questioned following recent findings of extremely rich and highly endemic benthic faunas. This problem is discussed using an index of cosmopolitanism to compare terrestrial and marine biotas.


2021 ◽  
Author(s):  
Tuomas Kärnä ◽  
Ida Ringgaard ◽  
Vasily Korabel ◽  
Adam Nord ◽  
Patrik Ljungemyr ◽  
...  

<p>We present Nemo-Nordic 2.0, the latest version of the operational marine forecasting model for the Baltic Sea used and developed in the Baltic Monitoring Forecasting Centre (BAL MFC) under the Copernicus Marine Environment Monitoring Service (CMEMS). The most notable differences between Nemo-Nordic 2.0 and its predecessor Nemo-Nordic 1.0 are the switch from NEMO 3.6 to NEMO 4.0 and an increase in horizontal resolution from 2 to 1 nautical mile. In addition, the model's bathymetry and bottom friction formulation have been updated. The model configuration was specially tuned to represent Major Baltic Inflow events. Focusing on a 2-year validation period from October 1, 2014, covering one Major Baltic Inflow event, Nemo-Nordic 2.0 simulates Sea Surface Height (SSH) well: centralized Root-Mean-Square Deviation (CRMSD) is within 10 cm for most stations outside the Inner Danish Waters. CRMSD is higher at some stations where small-scale topographical features cannot be correctly resolved. SSH variability tends to be overestimated in the Baltic Sea and underestimated in the Inner Danish Waters. Nemo-Nordic 2.0 represents Sea Surface Temperature (SST) and Salinity (SSS) well, although there is a negative bias around -0.5°C in SST. The 2014 Major Baltic Inflow event is well reproduced. The simulated salt pulse agrees well with observations in the Arkona basin and progresses into the Gotland basin in 3 to 4 months.</p>


2017 ◽  
Vol 14 (8) ◽  
pp. 2113-2131 ◽  
Author(s):  
Ye Liu ◽  
H. E. Markus Meier ◽  
Kari Eilola

Abstract. Long-term oxygen and nutrient transports in the Baltic Sea are reconstructed using the Swedish Coastal and Ocean Biogeochemical model (SCOBI) coupled to the Rossby Centre Ocean model (RCO). Two simulations with and without data assimilation covering the period 1970–1999 are carried out. Here, the weakly coupled scheme with the Ensemble Optimal Interpolation (EnOI) method is adopted to assimilate observed profiles in the reanalysis system. The reanalysis shows considerable improvement in the simulation of both oxygen and nutrient concentrations relative to the free run. Further, the results suggest that the assimilation of biogeochemical observations has a significant effect on the simulation of the oxygen-dependent dynamics of biogeochemical cycles. From the reanalysis, nutrient transports between sub-basins, between the coastal zone and the open sea, and across latitudinal and longitudinal cross sections are calculated. Further, the spatial distributions of regions with nutrient import or export are examined. Our results emphasize the important role of the Baltic proper for the entire Baltic Sea, with large net transport (export minus import) of nutrients from the Baltic proper into the surrounding sub-basins (except the net phosphorus import from the Gulf of Riga and the net nitrogen import from the Gulf of Riga and Danish Straits). In agreement with previous studies, we found that the Bothnian Sea imports large amounts of phosphorus from the Baltic proper that are retained in this sub-basin. For the calculation of sub-basin budgets, the location of the lateral borders of the sub-basins is crucial, because net transports may change sign with the location of the border. Although the overall transport patterns resemble the results of previous studies, our calculated estimates differ in detail considerably.


2018 ◽  
Vol 33 (6) ◽  
pp. 325-331
Author(s):  
Ilya A. Chernov ◽  
Nikolay G. Iakovlev

Abstract In the present paper we consider the first results of modelling the World Ocean biogeochemistry system within the framework of the Earth system model: a global atmosphere-ocean-ice-land-biogeochemistry model. It is based on the INMCM climate model (version INMCM39) coupled with the pelagic ecosystem model BFM. The horizontal resolution was relatively low: 2∘ × 2.5∘ for the ‘longitude’ and ‘latitude’ in transformed coordinates with the North Pole moved to land, 33 non-equidistant σ-horizons, 1 hour time step. We have taken into account 54 main rivers worldwide with run–off supplied by the atmosphere submodel. The setup includes nine plankton groups, 60 tracers in total. Some components sink with variable speed. We discuss challenges of coupling the BFM with the σ-coordinate ocean model. The presented results prove that the model output is realistic in comparison with the observed data, the numerical efficiency is high enough, and the coupled model may serve as a basis for further simulations of the long-term climate change.


2016 ◽  
Author(s):  
Ye Liu ◽  
H. E. Markus Meier ◽  
Kari Eilola

Abstract. The long-term oxygen and nutrient cycles in the Baltic Sea are reconstructed using the Swedish Coastal and Ocean Biogeochemical model (SCOBI) coupled to the Rossby Centre Ocean model (RCO). Two simulations covering the period 1970–1999 are carried out with and without data assimilation, respectively. Here, the "weakly coupled" scheme with the Ensemble Optimal Interpolation (EnOI) method is adopted to assimilate the observed profiles in the reanalysis system. The simulation results show considerable improvements in both oxygen and nutrient concentrations in the reanalysis relative to the free run. Further, the results suggest that the assimilation of biogeochemical observations has a significant effect on the simulation of the oxygen dependent dynamics of biogeochemical cycles. From the reanalysis, nutrient transports between subbasins, between the coastal zone and the open sea, and across latitudinal and longitudinal cross sections, are calculated. Further, bottom areas of nutrient import or export are examined. Our results emphasize the important role of the Baltic proper for the entire Baltic Sea, with large net exports of nutrients into the surrounding subbasins (except the phosphorus transport into the Gulf of Riga and the nitrogen transports into the Gulf of Riga and Danish Straits). In agreement with previous studies, we found that the Bothnian Sea imports large amounts of phosphorus from the Baltic proper that are buried in this subbasin. For the calculation of subbasin budgets, it is crucial where the lateral borders of the subbasins are located, because net transports may change sign with the location of the border. Although the overall transport patterns resemble the results of previous studies, our calculated estimates differ in detail considerably.


2019 ◽  
Vol 32 (11) ◽  
pp. 3089-3108 ◽  
Author(s):  
Ulf Gräwe ◽  
Knut Klingbeil ◽  
Jessica Kelln ◽  
Sönke Dangendorf

Abstract We analyzed changes in mean sea level (MSL) for the period 1950–2015 using a regional ocean model for the Baltic Sea. Sensitivity experiments allowed us to separate external from local drivers and to investigate individual forcing agents triggering basin-internal spatial variations. The model reveals a basin-average MSL rise (MSLR) of 2.08 ± 0.49 mm yr−1, a value that is slightly larger than the simultaneous global average of 1.63 ± 0.32 mm yr−1. This MSLR is, however, spatially highly nonuniform with lower than average increases in the southwestern part (1.71 ± 0.51 mm yr−1) and higher than average rates in the northeastern parts (2.34 ± 1.05 mm yr−1). While 75% of the basin-average MSL externally enters the Baltic basin as a mass signal from the adjacent North Sea, intensified westerly winds and a poleward shift of low pressure systems explain the majority of the spatial variations in the rates. Minor contributions stem from local changes in baroclinicity leading to a basin-internal redistribution of water masses. An observed increase in local ocean temperature further adds to the total basinwide MSLR through thermal expansion but has little effect on the spatial pattern. To test the robustness of these results, we further assessed the sensitivity to six different atmospheric surface forcing reanalysis products over their common period from 1980 to 2005. The ensemble runs indicated that there are significant differences between individual ensemble members increasing the total trend uncertainty for the basin average by 0.22 mm yr−1 (95% confidence intervals). Locally the uncertainty varies from 0.05 mm yr−1 in the central part to up to 0.4 mm yr−1 along the coasts.


Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 115-134
Author(s):  
Daniel Neumann ◽  
Matthias Karl ◽  
Hagen Radtke ◽  
Volker Matthias ◽  
René Friedland ◽  
...  

Abstract. The western Baltic Sea is impacted by various anthropogenic activities and stressed by high riverine and atmospheric nutrient loads. Atmospheric deposition accounts for up to a third of the nitrogen input into the Baltic Sea and contributes to eutrophication. Amongst other emission sources, the shipping sector is a relevant contributor to the atmospheric concentrations of nitrogen oxides (NOX) in marine regions. Thus, it also contributes to atmospheric deposition of bioavailable oxidized nitrogen into the Baltic Sea. In this study, the contribution of shipping emissions to the nitrogen budget in the western Baltic Sea is evaluated with the coupled three-dimensional physical biogeochemical model MOM–ERGOM (Modular Ocean Model–Ecological ReGional Ocean Model) in order to assess the relevance of shipping emissions for eutrophication. The atmospheric input of bioavailable nitrogen impacts eutrophication differently depending on the time and place of input. The shipping sector contributes up to 5 % to the total nitrogen concentrations in the water. The impact of shipping-related nitrogen is highest in the offshore regions distant from the coast in early summer, but its contribution is considerably reduced during blooms of cyanobacteria in late summer because the cyanobacteria fix molecular nitrogen. Although absolute shipping-related total nitrogen concentrations are high in some coastal regions, the relative contribution of the shipping sector is low in the vicinity of the coast because of high riverine nutrient loads.


2020 ◽  
Author(s):  
Felix Gross ◽  
Kilian Etter ◽  
Philipp Held ◽  
Jens Schneider von Deimling

<p>Seagrass meadows are crucial habitats since they serve as fish nurseries and food sources for many marine species. They prevent nearshore erosion and are an important CO<sub>2</sub> sink. As the plants are bound to the photic zone, seagrass meadows normally populate the shallow coastal zones. Unmanned aerial vehicles (UAV) are gaining popularity within the earth sciences community. Most surveys are of terrestrial nature and carried out by using the camera of the UAV to obtain orthophotos and three-dimensional surface models of a survey area. In comparison to space-borne systems, UAVs are capable of higher resolution image quality and time independent measurements, which enables an event-based surveying approach. We here present a submarine habitat mapping study, obtained by using an UAV flying 75 m above the water surface. Within the frame of the BONUS ECOMAP project, we aim to conduct repeated UAV surveys over the seasonal cycle to observe changes within coastal seagrass bed habitats. The key study area is located in the Baltic Sea offshore Heidkate (near Kiel, Germany). For data acquisition, we are using a commercial DJI Inspire 2 UAV with a gimbal mounted 20.8 megapixel Zenmuse X5S camera with a 15 mm/ 1.7 ASPH lens. For less reflection and distortion at the air-water interface, we are using a B&W circular polarized filter. Ground control points are measured and leveled with a Leica RTK system, which has a lateral resolution of ~2 cm. We process the data with the commercial software Pix4D™ and Agisoft PhotoScan™ to compute orthomosaic images and digital elevation/surface models. Since February 2018, we were able to conduct repeated surveys offshore Heidkate and Wendtorf (Germany). The average resolution of the orthomosaic data is better than 5 cm/px. First results show that we can obtain high-resolution images of habitats within water depths less than ~4 m in the Baltic Sea. Penetration is limited to factors like wave action, suspended sediment load and angle of the solar radiation. We perform supervised classification and pattern detection for habitat identification and discrimination. The data show the presence of seagrass, algae but also rocks, which are exposed at the seafloor. All scenes show a seasonal variability of the extent of seagrass meadows which are affected by migrating sand bars and major storm events. These data are the basis for a long-term monitoring framework, we are currently establishing in the working area.</p>


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