scholarly journals Accurate Sea Surface heights from Sentinel-3A and Jason-3 retrackers by incorporating High-Resolution Marine Geoid and Hydrodynamic Models

2021 ◽  
Vol 11 (1) ◽  
pp. 58-74
Author(s):  
M. Mostafavi ◽  
N. Delpeche-Ellmann ◽  
A. Ellmann
Keyword(s):  
High Resolution ◽  
Baltic Sea ◽  
Hydrodynamic Model ◽  
Average Distance ◽  
Sea Surface ◽  
Hydrodynamic Models ◽  
Geoid Model ◽  
Sea Surface Heights ◽  
Ice Conditions ◽  
The Baltic

Abstract One of the major challenges of satellite altimetry (SA) is to produce accurate sea surface heights data up to the shoreline, especially in geomorphologically complex sea areas. New advanced re-tracking methods are expected to deliver better results. This study examines the achievable accuracy of Sentinel-3A (S3A) and Jason-3 (JA3) standard retrackers (Ocean and MLE4) with that of improved retrackers adapted for coastal and sea ice conditions (ALES+ SAR for S3A and ALES+ for JA3). The validation of SA data was performed by the integration of tide gauges, hydrodynamic model and high-resolution geoid model. The geoid being a key component that links the vertical reference datum of the SA with other utilized sources. The method is tested in the eastern section of Baltic Sea. The results indicate that on average reliable sea surface height (SSH) data can be obtained 2–3 km from the coastline for S3A (for both Ocean and ALES+SAR) whilst an average distance of 7–10 km for JA3 (MLE4 and ALES+) with a minimum distance of 3–4 km. In terms of accuracy, the RMSE (with respect to a corrected hydrodynamic model) of S3A ALES+ SAR and Ocean retrackers based SSH were 4–5 cm respectively, whereas with the JA3 ALES+ and MLE4 associated SSH RMSE of 6–7 cm can be achieved. The ALES+ and ALES+ SAR retrackers show SSH improvement within a range of 0.5–1 cm compared to the standard retrackers. This assessment showed that the adaptation of localized retrackers for the Baltic Sea (ALES+ and ALES+SAR) produced more valid observation closer to the coast than the standard retrackers and also improved the accuracy of SSH data.

scholarly journals Assimilating high-resolution sea surface temperature data improves the ocean forecast potential in the Baltic Sea

Ocean Science ◽  
2018 ◽  
Vol 14 (3) ◽  
pp. 525-541 ◽  
Author(s):  
Ye Liu ◽  
Weiwei Fu
Keyword(s):  
High Resolution ◽  
Sea Ice ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Baltic Sea ◽  
Sea Surface ◽  
The Baltic Sea ◽  
Dependent Observations ◽  
The Baltic ◽  
The Impact

Abstract. We assess the impact of assimilating the satellite sea surface temperature (SST) data on the Baltic forecast, particularly on the forecast of ocean variables related to SST. For this purpose, a multivariable data assimilation (DA) system has been developed based on a Nordic version of the Nucleus for European Modelling of the Ocean (NEMO-Nordic). We use Kalman-type filtering to assimilate the observations in the coastal regions. Further, a low-rank approximation of the stationary background error covariance metrics is used at the analysis steps. High-resolution SST from the Ocean and Sea Ice Satellite Application Facility (OSISAF) is assimilated to verify the performance of the DA system. The assimilation run shows very stable improvements of the model simulation as compared with both independent and dependent observations. The SST prediction of NEMO-Nordic is significantly enhanced by the DA forecast. Temperatures are also closer to observations in the DA forecast than the model results in the water above 100 m in the Baltic Sea. In the deeper layers, salinity is also slightly improved. In addition, we find that sea level anomaly (SLA) is improved with the SST assimilation. Comparisons with independent tide gauge data show that the overall root mean square error (RMSE) is reduced by 1.8 % and the overall correlation coefficient is slightly increased. Moreover, the sea-ice concentration forecast is improved considerably in the Baltic Proper, the Gulf of Finland and the Bothnian Sea during the sea-ice formation period, respectively.

scholarly journals Assimilating High-resolution Sea Surface Temperature Data Improves the Ocean Forecast in the Baltic Sea

2018 ◽  
Author(s):  
Ye Liu ◽  
Weiwei Fu
Keyword(s):  
High Resolution ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Baltic Sea ◽  
Model Simulation ◽  
Sea Surface ◽  
The Baltic Sea ◽  
Dependent Observations ◽  
The Baltic ◽  
The Impact

Abstract. We assess the impact of assimilating the satellite sea surface temperature (SST) data on the Baltic forecast, practically on the forecast of ocean variables related to SST. For this purpose, a multivariable data assimilation (DA) system has been developed based on a Nordic version of the Nucleus for European Modelling of the Ocean (NEMO-Nordic). We use a localized Singular Evolutive Interpolated Kalman (SEIK) filter to characterize correlation scales in the coastal regions. High resolution SST from OSISAF is assimilated to verify the performance of DA system. The assimilation run shows very stable improvements on the model simulation as compared with both independent and dependent observations. The SST prediction of NEMO-Nordic is significantly enhanced by the DA system. Temperatures are also closer to observation in the DA system than the model results in the water above 100 m in the Baltic Sea. In the deeper layers, salinity is also slightly improved. Besides, we find that Sea level anomaly (SLA) is improved with the SST assimilation. Comparison with independent tide gauge data show that overall root mean square error (RMSE) is reduced by 1.8 % and overall correlation coefficient is increased by 0.4 %. Moreover, the sea ice concentration forecast is improved considerably in the Baltic proper, the Gulf of Finland and the Bothnian Sea, respectively.

scholarly journals Combining Satellite Imagery and Numerical Modelling to Study the Occurrence of Warm Upwellings in the Southern Baltic Sea in Winter

2019 ◽  
Vol 11 (24) ◽  
pp. 2982
Author(s):  
Halina Kowalewska-Kalkowska ◽  
Marek Kowalewski
Keyword(s):  
High Resolution ◽  
Baltic Sea ◽  
Satellite Imagery ◽  
Hydrodynamic Model ◽  
Coastal Upwelling ◽  
Eastern Coast ◽  
The Baltic Sea ◽  
Southern Baltic Sea ◽  
Southern Baltic ◽  
The Baltic

Coastal upwelling involves an upward movement of deeper, usually colder, water to the surface. Satellite sea surface temperature (SST) observations and simulations with a hydrodynamic model show, however, that the coastal upwelling in the Baltic Sea in winter can bring warmer water to the surface. In this study, the satellite SST data collected by the advanced very high resolution radiometer (AVHRR) and the moderate-resolution imaging spectroradiometer (MODIS), as well as simulations with the Parallel Model 3D (PM3D) were used to identify upwelling events in the southern Baltic Sea during the 2010–2017 winter seasons. The PM3D is a three-dimensional hydrodynamic model of the Baltic Sea developed at the Institute of Oceanography, University of Gdańsk, Poland, in which parallel calculations enable high-resolution modelling. A validation of the model results with in situ observations and satellite-derived SST data showed the PM3D to adequately represent thermal conditions in upwelling areas in winter (91.5% agreement). Analysis of the frequency of warm upwellings in 12 areas of the southern Baltic Sea showed a high variability in January and February. In those months, the upwelling was most frequent, both in satellite imagery and in model results, off the Hel Peninsula (38% and 43% frequency, respectively). Upwelling was also frequent off the Vistula Spit, west of the Island of Rügen, and off the eastern coast of Skåne, where the upwelling frequency estimated from satellite images exceeded 26%. As determined by the PM3D, the upwelling frequency off VS and R was at least 25%, while off the eastern coast of Skåne, it reached 17%. The faithful simulation of SST variability in the winters of 2010–2017 by the high-resolution model used was shown to be a reliable tool with which to identify warm upwellings in the southern Baltic Sea.

Variability of Sea Surface Heights in the Baltic Sea: An Intercomparison of Observations and Model Simulations

2006 ◽  
Vol 29 (2) ◽  
pp. 113-134 ◽  
Author(s):  
Kristin Novotny ◽  
Gunter Liebsch ◽  
Andreas Lehmann ◽  
Reinhard Dietrich
Keyword(s):  
Baltic Sea ◽  
Sea Surface ◽  
The Baltic Sea ◽  
Model Simulations ◽  
Sea Surface Heights ◽  
The Baltic

MODERN TECHNOLOGY IN DUNE COMPLEXES MONITORING ON THE VISTULA SPIT

2017 ◽  
Author(s):  
Aleksandr Danchenkov ◽  
Aleksandr Danchenkov
Keyword(s):  
High Resolution ◽  
Baltic Sea ◽  
Spatial Data ◽  
Modern Technology ◽  
High Potential ◽  
Coastal Processes ◽  
The Baltic Sea ◽  
Widespread Application ◽  
The Baltic ◽  
Modern Technologies

Modern technologies, which provide fast and accurate acquisition of high-resolution spatial data, have found widespread application in the monitoring of coastal processes. This paper reports the results of four years’ monitoring of a huge deflation/blowout/wind-scour basin dynamics at the Vistula Spit (southeast coast of the Baltic Sea). Information about the volume and size dynamics together with deflation/accumulation schemes and 3D elevation maps is presented. Basing on the obtained results, forecast of the deflation basin dynamics for 2016 was proposed. This paper implements the Terrestrial Laserscanning (TLS) method to the coastal processes investigation and demonstrates its high potential in this field.

MODERN TECHNOLOGY IN DUNE COMPLEXES MONITORING ON THE VISTULA SPIT

2017 ◽  
Author(s):  
Aleksandr Danchenkov ◽  
Aleksandr Danchenkov
Keyword(s):  
High Resolution ◽  
Baltic Sea ◽  
Spatial Data ◽  
Modern Technology ◽  
High Potential ◽  
Coastal Processes ◽  
The Baltic Sea ◽  
Widespread Application ◽  
The Baltic ◽  
Modern Technologies

Modern technologies, which provide fast and accurate acquisition of high-resolution spatial data, have found widespread application in the monitoring of coastal processes. This paper reports the results of four years’ monitoring of a huge deflation/blowout/wind-scour basin dynamics at the Vistula Spit (southeast coast of the Baltic Sea). Information about the volume and size dynamics together with deflation/accumulation schemes and 3D elevation maps is presented. Basing on the obtained results, forecast of the deflation basin dynamics for 2016 was proposed. This paper implements the Terrestrial Laserscanning (TLS) method to the coastal processes investigation and demonstrates its high potential in this field.

scholarly journals Remote Sensing Supported Sea Surface pCO2 Estimation and Variable Analysis in the Baltic Sea

2021 ◽  
Vol 13 (2) ◽  
pp. 259
Author(s):  
Shuping Zhang ◽  
Anna Rutgersson ◽  
Petra Philipson ◽  
Marcus B. Wallin
Keyword(s):  
Remote Sensing ◽  
Baltic Sea ◽  
Mean Squared Error ◽  
Numerical Models ◽  
Mixed Layer Depth ◽  
Sea Surface ◽  
The Baltic Sea ◽  
Chl A ◽  
Marginal Seas ◽  
The Baltic

Marginal seas are a dynamic and still to large extent uncertain component of the global carbon cycle. The large temporal and spatial variations of sea-surface partial pressure of carbon dioxide (pCO2) in these areas are driven by multiple complex mechanisms. In this study, we analyzed the variable importance for the sea surface pCO2 estimation in the Baltic Sea and derived monthly pCO2 maps for the marginal sea during the period of July 2002–October 2011. We used variables obtained from remote sensing images and numerical models. The random forest algorithm was employed to construct regression models for pCO2 estimation and produce the importance of different input variables. The study found that photosynthetically available radiation (PAR) was the most important variable for the pCO2 estimation across the entire Baltic Sea, followed by sea surface temperature (SST), absorption of colored dissolved organic matter (aCDOM), and mixed layer depth (MLD). Interestingly, Chlorophyll-a concentration (Chl-a) and the diffuse attenuation coefficient for downwelling irradiance at 490 nm (Kd_490nm) showed relatively low importance for the pCO2 estimation. This was mainly attributed to the high correlation of Chl-a and Kd_490nm to other pCO2-relevant variables (e.g., aCDOM), particularly in the summer months. In addition, the variables’ importance for pCO2 estimation varied between seasons and sub-basins. For example, the importance of aCDOM were large in the Gulf of Finland but marginal in other sub-basins. The model for pCO2 estimate in the entire Baltic Sea explained 63% of the variation and had a root of mean squared error (RMSE) of 47.8 µatm. The pCO2 maps derived with this model displayed realistic seasonal variations and spatial features of sea surface pCO2 in the Baltic Sea. The spatially and seasonally varying variables’ importance for the pCO2 estimation shed light on the heterogeneities in the biogeochemical and physical processes driving the carbon cycling in the Baltic Sea and can serve as an important basis for future pCO2 estimation in marginal seas using remote sensing techniques. The pCO2 maps derived in this study provided a robust benchmark for understanding the spatiotemporal patterns of CO2 air-sea exchange in the Baltic Sea.

Variational assimilation of observation data in the mathematical model of the Baltic Sea dynamics

2015 ◽  
Vol 30 (4) ◽  
Author(s):  
Valeriy I. Agoshkov ◽  
Eugene I. Parmuzin ◽  
Vladimir B. Zalesny ◽  
Victor P. Shutyaev ◽  
Natalia B. Zakharova ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Heat Flux ◽  
Baltic Sea ◽  
Satellite Observation ◽  
Sea Surface ◽  
Observation Data ◽  
The Baltic Sea ◽  
Variational Assimilation ◽  
The Baltic ◽  
The Mathematical Model

AbstractA mathematical model of the dynamics of the Baltic Sea is considered. A problem of variational assimilation of sea surface temperature (SST) data is formulated and studied. Based on variational assimilation of satellite observation data, an algorithm solving the inverse problem of heat flux restoration on the interface of two media is proposed. The results of numerical experiments reconstructing the heat flux functions in the problem of variational assimilation of SST observation data are presented. The influence of SST assimilation on other hydrodynamic parameters of the model is considered.

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