Towards operational NEMO model for the Baltic Sea

2020 ◽  
Author(s):  
Tuomas Kärnä ◽  
Jonni Lehtiranta ◽  
Laura Tuomi
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Model Development ◽  
Circulation Model ◽  
Water Levels ◽  
Sea Surface Salinity ◽  
The Baltic Sea ◽  
Surface Salinity ◽  
Ice Coverage ◽  
The Baltic

<p>We are developing a new operational circulation model for the Baltic Sea using NEMO v4.0. The model configuration is derived from the NEMO v3.6 1 nmi NemoNordic setup (Hordoir et al., Geoscientific Model Development, 2019). A pre-operational version of the model has been implemented to produce daily forecasts of water level, temperature, salinity, and currents, as well as sea ice coverage. In this poster we present model validation for a two-year hindcast simulation. The results indicate that daily and seasonal variability of water levels and sea surface salinity are well captured. Sea ice coverage is well represented, although slightly over-estimated. Comparisons at several mooring locations show realistic vertical salinity structure, and verify that the model can simulate Baltic inflow events. Overall, the model skill has significantly improved compared to previous operational models.</p>

scholarly journals First regional SMOS Sea Surface Salinity products over the Baltic Sea and its oceanographic added-value

2020 ◽  
Author(s):  
Veronica Gonzalez-Gambau ◽  
Estrella Olmedo ◽  
Cristina Gonzalez-Haro ◽  
Antono Turiel ◽  
Justino Martinez ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Numerical Models ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Added Value ◽  
The Baltic Sea ◽  
Surface Salinity ◽  
Validation Data ◽  
The Baltic

<p>Accurate satellite-based sea surface salinity (SSS) fields would address some gaps of knowledge and benefit the understanding of Baltic Sea salinity dynamics.  In particular, these fields can contribute to the monitoring of long-term salinity changes and to the detection of periods with anomalous salinity. These products can also be very useful as initial fields and validation data for improving the existing numerical models.</p><p><br>The Baltic Sea is one of the most challenging regions for the retrieval of SSS from L-band satellite measurements. Nowadays, available EO-based SSS products are quite limited over this region both in terms of spatio-temporal coverage and quality. This is mainly due to several technical limitations that strongly affect the SMOS TB particularly over semi-enclosed seas, such as the high contamination by Radio-Frequency Interference (RFI) sources and the contamination close to land and ice edges. Besides, the sensitivity of TB to SSS changes is very low in cold waters and much larger errors are expected compared to temperate oceans. Salinity and temperature values are very low in this basin, which implies that dielectric constant models are not fully tested in such conditions. In the recent years, the Barcelona Expert Center team has been working on the development of innovative algorithms for improving the quality of SMOS TB and SSS retrievals dealing with the main processing issues. </p><p><br>In the context of the ESA Baltic+ Salinity Dynamics project (https://balticsalinity.argans.co.uk/), these methodologies have been adapted and consolidated towards the generation of the first  regional SMOS SSS product (2011-2020) that would suit to the needs of the Baltic research community. Very recently, the first version of the Baltic+ SSS product has been produced (3-year series) and is currently under validation against in-situ measurements. The quality assessment of the SSS product in the Baltic Sea is also an issue and its representativeness must be carefully assessed. The basin is strongly stratified and then, the differences between SMOS measurements (first centimeters) and in-situ observations (few meters depth) can be noticeable. Differences are more probable during ice melting and high runoff events in spring where there might be a freshwater layer at the top shallow surface. Feedback from the users will help identifying the limitations of the product. Additional technical developments will be addressed to meet the requirements of the communities working in the study of Baltic processes. </p><p><br>We will present at the conference the Baltic+ SSS v1 product and its added-value with respect to other existing EO-based datasets. The potential scientific impact of this satellite SSS product in advancing on-going regional research initiatives like the Baltic Earth Working Group on Salinity dynamics will be discussed.</p>

scholarly journals Nemo-Nordic 2.0: Operational marine forecast model for the Baltic Sea

2021 ◽  
Author(s):  
Tuomas Kärnä ◽  
Patrik Ljungemyr ◽  
Saeed Falahat ◽  
Ida Ringgaard ◽  
Lars Axell ◽  
...  
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Sea Level ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Forecast Model ◽  
The Baltic Sea ◽  
Baltic Basin ◽  
The North ◽  
The Baltic

Abstract. This paper describes Nemo-Nordic 2.0, an operational marine forecast model for the Baltic Sea. The model is based on the NEMO (Nucleus for European Modelling of the Ocean) circulation model and the previous Nemo-Nordic 1.0 configuration by Hordoir et al. [Geosci. Model Dev., 12, 363–386, 2019]. The most notable updates include the switch from NEMO version 3.6 to 4.0, updated model bathymetry and revised bottom friction formulation. The model domain covers the Baltic and the North Seas with approximately 1 nautical mile resolution. Vertical grid resolution has been increased from 3 to 1 m in the surface layer. In addition, the numerical solver configuration has been revised to reduce artificial mixing to improve the representation of inflow events. Sea-ice is modeled with the SI3 model instead of LIM3. The model is validated against sea level, water temperature and salinity observations, as well as Baltic Sea ice chart data for a two-year hindcast simulation. Sea level root mean square deviation (RMSD) is typically within 10 cm throughout the Baltic basin. Seasonal sea surface temperature variation is well captured, although the model exhibits a negative bias of approximately −0.5 °C. Salinity RMSD is typically below 1.5 g/kg. The model captures the 2014 Major Baltic Inflow event and its propagation to the Gotland Deep. The skill analysis demonstrates that Nemo-Nordic 2.0 can reproduce the hydrographic features of the Baltic Sea.

scholarly journals First SMOS Sea Surface Salinity dedicated products over the Baltic Sea

2022 ◽  
Author(s):  
Verónica González-Gambau ◽  
Estrella Olmedo ◽  
Antonio Turiel ◽  
Cristina González-Haro ◽  
Aina García-Espriu ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Numerical Models ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
The Baltic Sea ◽  
Surface Salinity ◽  
L Band ◽  
The Baltic ◽  
The Impact

Abstract. This paper presents the first Soil Moisture and Ocean Salinity (SMOS) Sea Surface Salinity (SSS) dedicated products over the Baltic Sea. The SSS retrieval from L-band brightess temperature (TB) measurements over this basin is really challenging due to important technical issues, such as the land-sea and ice-sea contamination, the high contamination by Radio-Frequency Interferences (RFI) sources, the low sensitivity of L-band TB at SSS changes in cold waters and the poor characterization of dielectric constant models for the low SSS and SST ranges in the basin. For these reasons, exploratory research in the algorithms used from the level 0 up to level 4 has been required to develop these dedicated products. This work has been performed in the framework of the European Space Agency regional initiative Baltic+ Salinity Dynamics. Two Baltic+ SSS products have been generated for the period 2011–2019 and are freely distributed: the Level 3 (L3) product (daily generated 9-day maps in a 0.25° grid, https://doi.org/10.20350/digitalCSIC/13859) (González-Gambau et al., 2021a) and the Level 4 (L4) product (daily maps in a 0.05° grid, https://doi.org/10.20350/digitalCSIC/13860) (González-Gambau et al., 2021b)), that are computed by applying multifractal fusion to L3 SSS with Sea Surface Temperature (SST) maps. The accuracy of L3 SSS products is typically around 0.7–0.8 psu. The L4 product has an improved spatio-temporal resolution with respect to the L3 and the accuracy is typically around 0.4 psu. Regions with the highest errors and limited coverage are located in Arkona and Bornholm basins and Gulfs of Finland and Riga. The impact assessment of Baltic+ SSS products has shown that they can help in the understanding of salinity dynamics in the basin. They complement the temporally and spatially very sparse in situ measurements, covering data gaps in the region and they can also be useful for the validation of numerical models, particularly in areas where in situ data are very sparse.

scholarly journals First regional SMOS Sea Surface Salinity products over the Baltic Sea: quality assessment and oceanographic added-value

2021 ◽  
Author(s):  
Veronica Gonzalez Gambau ◽  
Estrella Olmedo ◽  
Cristina Gonzalez Haro ◽  
Antonio Turiel ◽  
Aina Garcia ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Exchange ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
The Baltic Sea ◽  
Surface Salinity ◽  
Model Simulations ◽  
The North ◽  
The Baltic

<p>The Baltic Sea is a strongly stratified semi-enclosed sea with a large freshwater supply from rivers, net precipitation and water exchange and high-saline water from the North Sea through the Kattegat Strait. In the Danish Straits the water exchange is hampered by bathymetric constraints , such as narrow and shallow sills, and by hydrodynamic restrictions, such as fronts and mixing. The shallow depth of the Baltic Sea (i.e. 54 m in average) yields to highly variable ocean dynamics controlled mainly by local atmospheric forcing. The water exchange between the Baltic Sea and the North Atlantic Ocean is restricted by the narrows and sills of the Danish Straits (i.e. via Kattergat Strait at the East of the Baltic Sea) and by different river outflows distributed across the Baltic Sea. The bottom water in the deep sub-basins is ventilated mainly by large perturbations, so-called major Baltic saltwater inflows. The occurrence of these events needs still further investigation. The description of the complex oceanographic conditions within the Baltic Sea in current model simulations could also be developed. Furthermore, model simulations of the Baltic Sea are constrained to the initialization of the model (i.e. parametrization of the initial surface atmospheric and ocean conditions).</p><p>For this, the Earth Observation salinity measurements have a great potential to help in the understanding of the dynamics in the basin and to improve the regional models there. However, the Baltic Sea is one of the most challenging regions for the sea surface salinity (SSS) retrieval from satellite measurements. The available EO-based SSS products are quite limited over this region both in terms of spatio-temporal coverage and quality. This is mainly due to several technical limitations that strongly affect the satellite brightness temperatures (TB) measurements, particularly over semi-enclosed seas, such as the high contamination by Radio-Frequency Interferences (RFI) and the contamination close to land and ice edges. Besides, the sensitivity of TB to SSS changes is very low in cold waters and much larger errors are expected compared to temperate oceans.</p><p>As a main result of the ESA Baltic+ Salinity Dynamics project (<span></span>), a new regional SSS product derived from the measurements provided by the European Soil Moisture and Ocean Salinity (SMOS) mission has been developed. In this work, first, we describe briefly the enhanced algorithms used in the generation of SMOS SSS fields. Second, we show a complete quality assessment by comparing the satellite and the in situ salinity measurements. For this, we use in situ measurements provided by SeaDataNet and Helcom and Ferry box lines. Finally, we compare the satellite salinity measurements with the salinity fields provided by a model. We focus our analysis in two aspects: i) the description of the freswater fluxes coming from continental discharge and sea-ice melting; and ii) the capability of describing the dynamics of the saltier Atlantic water that enters into the basin through the Kattegat strait.</p><p> </p>

scholarly journals Nemo-Nordic 2.0: operational marine forecast model for the Baltic Sea

2021 ◽  
Vol 14 (9) ◽  
pp. 5731-5749
Author(s):  
Tuomas Kärnä ◽  
Patrik Ljungemyr ◽  
Saeed Falahat ◽  
Ida Ringgaard ◽  
Lars Axell ◽  
...  
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Water Temperature ◽  
Sea Level ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Sea Surface ◽  
Model Assessment ◽  
The Baltic Sea ◽  
The Baltic

Abstract. This paper describes Nemo-Nordic 2.0, an operational marine model for the Baltic Sea. The model is used for both near-real-time forecasts and hindcast purposes. It provides estimates of sea surface height, water temperature, salinity, and velocity, as well as sea ice concentration and thickness. The model is based on the NEMO (Nucleus for European Modelling of the Ocean) circulation model and the previous Nemo-Nordic 1.0 configuration by Hordoir et al. (2019). The most notable updates include the switch from NEMO version 3.6 to 4.0, updated model bathymetry, and revised bottom friction formulation. The model domain covers the Baltic Sea and the North Sea with approximately 1 nmi resolution. Vertical grid resolution has been increased from 3 to 1 m in the surface layer. In addition, the numerical solver configuration has been revised to reduce artificial mixing to improve the representation of inflow events. Sea ice is modeled with the SI3 model instead of LIM3. The model is validated against sea level, water temperature, and salinity observations, as well as Baltic Sea ice chart data for a 2-year hindcast simulation (October 2014 to September 2016). Sea level root mean square deviation (RMSD) is typically within 10 cm throughout the Baltic basin. Seasonal sea surface temperature variation is well captured, although the model exhibits a negative bias of approximately −0.5 ∘C. Salinity RMSD is typically below 1.5 g kg−1. The model captures the 2014 major Baltic inflow event and its propagation to the Gotland Deep. The model assessment demonstrates that Nemo-Nordic 2.0 can reproduce the hydrographic features of the Baltic Sea.

scholarly journals Diatom-based estimation of sea surface salinity in the south Baltic Sea and Kattegat

Baltica ◽  
2014 ◽  
Vol 27 (2) ◽  
pp. 131-140 ◽  
Author(s):  
Bartosz Kotrys ◽  
Michał Tomczak ◽  
Andrzej Witkowski ◽  
Jan Harff ◽  
Jan Seidler
Keyword(s):  
Baltic Sea ◽  
Mean Squared Error ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
The Baltic Sea ◽  
Surface Salinity ◽  
Xrf Core Scanner ◽  
High Precipitation ◽  
The Baltic ◽  
Artificial Neuronal Network

A new diatom-based sea surface salinity (SSS) estimation has been applied to a collection of 27 taxa in 48 present-day sediment and surface water samples recovered in the Baltic Sea and Kattegat. The sediment core 303610-12 (2005) from the Eastern Gotland was chosen for study of Holocene sequence, ranging the last 8160 yrs BP. The Artificial Neuronal Network (ANN) method allows the estimation of spring SSS (March-April) values ranging between 7.04 ‰ and 8.25 ‰ at an averaged Root Mean Squared Error (RMSE) of 0.49 ‰. The rather low amplitude of salinity change might be caused by mixing of fresh water with upper surface layer of the Baltic Sea due to high precipitation and riverine input. The estimates of spring SSS from core 303610-12 were compared with independent geochemical proxies for salinity (K, Ti and S) derived from XRF Core Scanner record. Conspicuous correlation between salinity and sulphur records and reverse-correlation to K and Ti demonstrates that the ANN method combined with quantitative and qualitative analyses of diatoms provides a useful tool for palaeosalinity reconstructions in the Holocene sediments of the Baltic Sea

Hydrological and sedimentation conditions in a non-tidal lagoon during ice coverage – The example of Vistula Lagoon in the Baltic Sea

2019 ◽  
Vol 216 ◽  
pp. 38-53 ◽  
Author(s):  
Boris Chubarenko ◽  
Vladimir Chechko ◽  
Aleksander Kileso ◽  
Elena Krek ◽  
Viktoria Topchaya
Keyword(s):  
Baltic Sea ◽  
Vistula Lagoon ◽  
The Baltic Sea ◽  
Ice Coverage ◽  
The Baltic ◽  
Sedimentation Conditions

scholarly journals Operational SAR-based sea ice drift monitoring over the Baltic Sea

Ocean Science ◽  
2012 ◽  
Vol 8 (4) ◽  
pp. 473-483 ◽  
Author(s):  
J. Karvonen
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Vector Fields ◽  
Phase Correlation ◽  
The Baltic Sea ◽  
Sar Images ◽  
Envisat Asar ◽  
Ice Drift ◽  
Sea Ice Drift ◽  
The Baltic

Abstract. An algorithm for computing ice drift from pairs of synthetic aperture radar (SAR) images covering a common area has been developed at FMI. The algorithm has been developed based on the C-band SAR data over the Baltic Sea. It is based on phase correlation in two scales (coarse and fine) with some additional constraints. The algorithm has been running operationally in the Baltic Sea from the beginning of 2011, using Radarsat-1 ScanSAR wide mode and Envisat ASAR wide swath mode data. The resulting ice drift fields are publicly available as part of the MyOcean EC project. The SAR-based ice drift vectors have been compared to the drift vectors from drifter buoys in the Baltic Sea during the first operational season, and also these validation results are shown in this paper. Also some navigationally useful sea ice quantities, which can be derived from ice drift vector fields, are presented.

scholarly journals Effects of surface current/wind interaction in an eddy-rich general ocean circulation simulation of the Baltic Sea

2016 ◽  
Author(s):  
H. Dietze ◽  
U. Löptien
Keyword(s):  
Baltic Sea ◽  
Ocean Circulation ◽  
Surface Waters ◽  
Algal Blooms ◽  
Circulation Model ◽  
Transport Processes ◽  
Surface Currents ◽  
Wind Effects ◽  
The Baltic Sea ◽  
The Baltic

Abstract. Deoxygenation in the Baltic Sea endangers fish yields and favours noxious algal blooms. Yet, vertical transport processes ventilating the oxygen-deprived waters at depth and replenishing nutrient-deprived surface waters (thereby fuelling export of organic matter to depth), are not comprehensively understood. Here, we investigate the effects of the interaction between surface currents and winds (also referred to as eddy/wind effects) on upwelling in an eddy-rich general ocean circulation model of the Baltic Sea. Contrary to expectations we find that accounting for current/wind effects does inhibit the overall vertical exchange between oxygenated surface waters and oxygen-deprived water at depth. At major upwelling sites, however, as e.g. off the south coast of Sweden and Finland, the reverse holds: the interaction between topographically steered surface currents with winds blowing over the sea results in a climatological sea surface temperature cooling of 0.5 K. This implies that current/wind effects drive substantial local upwelling of cold and nutrient-replete waters.

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