Improving the multiannual, high-resolution modelling of biogeochemical
                        cycles in the Baltic Sea by using data assimilation

Liu, Ye; Meier, H. E. Markus; Eilola, Kari

doi:10.3402/tellusa.v66.24908

Cited by 9 publications

(24 citation statements)

References 47 publications

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“…Other "sophisticated" sample ensembles could be tested but this is beyond the scope of this study. An adaptive scaling factor was calculated to adapt to the instantaneous forecast error variance before each local analysis (Liu et al, 2013(Liu et al, , 2014. Further, localization is used to remove unrealistic long-range correlations with a quasi-Gaussian function and a uniform horizontal correlation scale of 70 km.…”

Section: Observationsmentioning

confidence: 99%

“…One experiment is a simulation without data assimilation (FREE). The other simulation is constrained by observations using the "weakly coupled" assimilation scheme based upon the EnOI method following Liu et al (2014) which was briefly described above (REANA). Both simulations, FREE and RE-ANA, are initialized for January 1970.…”

Section: Observationsmentioning

confidence: 99%

“…Fu (2016) analyzed the response of a coupled physical-biogeochemical model to the improved hydrodynamics in the Baltic Sea. Recently, several data assimilation studies have focused on the historical reanalysis of salinity and temperature in the Baltic Sea (e.g., Fu et al, 2012;Liu et al, 2013Liu et al, , 2014. Reanalysis has helped enormously in making the historical record of observed ocean parameters more homogeneous and useful for many purposes.…”

Section: Introductionmentioning

confidence: 99%

“…The present paper focuses on the assimilation of profiles of temperature, salinity, nutrients and oxygen in the Baltic Sea following Liu et al (2014). We aim to reproduce the ocean biogeochemical state with the help of information from both observations and a coupled physical-biogeochemical model for the period 1970-1999.…”

Section: Introductionmentioning

confidence: 99%

“…For example, Liu et al (2014) used the Ensemble Optimal Interpolation (EnOI) method to improve the multi-annual, high-resolution modeling of biogeochemical dynamics in the Baltic Sea. Fu (2016) analyzed the response of a coupled physical-biogeochemical model to the improved hydrodynamics in the Baltic Sea.…”

Section: Introductionmentioning

confidence: 99%

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Nutrient transports in the Baltic Sea – results from a 30-year physical–biogeochemical reanalysis

2017

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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.

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Section: Observationsmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nutrient transports in the Baltic Sea – results from a 30-year physical–biogeochemical reanalysis

2017

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The Assimilation of Temperature and Salinity Profile Observations for Forecasting the River–Estuary–Shelf Waters

Liu

Xie²,

Liu

et al. 2021

JGR Oceans

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The circulation and hydrographic properties of the river-estuary-shelf (RES) waters off the Pearl River Estuary (PRE, Figure 1) are highly variable in space and time due to multi-forcing of tides, winds, and buoyancy from river discharge (Liu & Gan, 2020;Zu & Gan, 2015). These RES waters are shallower than 50 m with complex bathymetry and are driven by strong wind and tidal forcing as well as remote forcing from the neighboring basin circulation in the northern South China Sea (NSCS, Figure 1). The PRE bathymetry is characterized by a wide shallow western bank and two relatively deep navigation channels in the eastern segment. Hong Kong Waters are characterized as a coastal embayment that is influenced by the waters from the PRE to the west, from Mirs Bay to the east, and from the continental shelf off Hong Kong to the south. The annually averaged river discharge from the Pearl River to the continental shelf is ∼10,000 m 3 s −1 (Zu & Gan, 2015). These buoyant waters rush out of the estuary and form a notable buoyant plume over the shelf. As a result, the interaction between the plume and the wind-driven shelf circulation changes the pattern

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Summer heatwaves on the Baltic Sea seabed contribute to oxygen deficiency in shallow areas

Safonova,

Meier,

Gröger

2024

Commun Earth Environ

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Since the early 1980ies, the shallow and brackish Baltic Sea, located in northern Europe, has warmed fastest of all the world’s coastal seas. Hence, the total heat exposure during marine heatwaves increased in frequency and duration, which may have a major impact on the marine ecosystem. We found that marine heatwaves, using two different, commonly used definitions, occurred everywhere on the sea surface since the early 1990s. Periods with sea surface temperatures larger than 20 °C lasting longer than 10 days were particularly numerous in the shallow coastal zone of the southern and eastern Baltic Sea. Furthermore, summer marine heatwaves that reached the seabed mainly occurred in water depths of less than 20 m, where they led to a decrease in oxygen concentration. Since the early 1990s, a positive trend in the expansion of marine heatwaves has been observed on the seabed. The increasing number of marine heatwaves increases the risk of hypoxia events in the coastal zone.

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Improving the multiannual, high-resolution modelling of biogeochemical cycles in the Baltic Sea by using data assimilation

Cited by 9 publications

References 47 publications

Nutrient transports in the Baltic Sea – results from a 30-year physical–biogeochemical reanalysis

Nutrient transports in the Baltic Sea – results from a 30-year physical–biogeochemical reanalysis

The Assimilation of Temperature and Salinity Profile Observations for Forecasting the River–Estuary–Shelf Waters

Summer heatwaves on the Baltic Sea seabed contribute to oxygen deficiency in shallow areas

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