Sergey Danilov

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

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Papers

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i-10 index

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Document Type

Co-Authors

Qiang Wang

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

163

Dmitry Sidorenko

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

150

Jens Schröter

University of Bonn

112

Thomas Jung

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

108

Nikolay Koldunov

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Claudia Wekerle

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Dmitry Sein

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Patrick Scholz

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Alexey Androsov

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Vera Fofonova

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Cooperative Institutions

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

132

Centre National de la Recherche Scientifique

GEOMAR Helmholtz Centre for Ocean Research Kiel

NSF National Center for Atmospheric Research

Max Planck Institute for Meteorology

Massachusetts Institute of Technology

Universität Hamburg

National Oceanography Centre

University of Bremen

Princeton University

Author Statistics

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Research Field

Comparing the steric height in the Northern Atlantic with satellite altimetry

V. O. Ivchenko Sergey Danilov Dmitry Sidorenko J. Schroeter Manfred Wenzel

Abstract. Anomalies of dynamic height derived from an analysis of Argo profiling buoys data are analysed to assess the relative roles of contributions from temperature and salinity over the North Atlantic for the period of 1999–2004. They are compared with dynamic topography anomalies based on TOPEX/Poseidon and Jason altimetry. It is shown that the halosteric contribution to the anomalies of dynamic height is comparable in magnitude to the thermosteric one over the period analyzed. Taking both salinity and temperature into account improves the agreement between zonally averaged trends in the satellite dynamic topography and dynamic height increasing the correlation between them to 0.73 from 0.63 when only temperature variability is taken into account. The implication of this result is that the salinity contribution cannot be neglected in the North Atlantic and that one cannot rely on estimating the thermosteric part by anomalies in the sea surface dynamic topography derived from the satellite altimetry.

Argo

Satellite Altimetry

Dynamic height

Ocean surface topography

Temperature salinity diagrams

Sea-surface height

10.5194/osd-4-441-2007

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Citations (2)

On the impact of wind forcing on the seasonal variability of Weddell Sea Bottom Water transport

Geophysical Research Letters (2012)

Qiang Wang Sergey Danilov E. Fahrbach Jens Schröter Thomas Jung

The seasonal variability of Weddell Sea Bottom Water (WSBW) transport and its driving mechanisms are examined using FESOM simulations. Pronounced seasonal variability is present in both the Filchner shelf water export rate and the WSBW transport rate near the Antarctic Peninsula (AP) tip. The variabilities at both locations are linked to the surface wind forcing. The Filchner shelf water export rate responds to the onshore propagating density anomaly, which is caused by the wind‐induced variation of the isopycnal depression at the coast. The variability near the AP tip originates from upstream variations at the Filchner Depression and from seasonal variability of the Weddell gyre strength.

Isopycnal

Antarctic Bottom Water

Forcing (mathematics)

Seasonality

10.1029/2012gl051198

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Citations (39)

Mesoscale eddies on unstructured meshes

Sergey Danilov Qiang Wang Dmitry Sein Dmitry Sidorenko

Mesoscale eddies contribute to the dynamics of ocean circulation in many important ways. Resolving them in the context of global ocean simulations still present a challenge because the Rossby radius of deformation is highly variable and can be as small as several km at high latitudes. Models formulated on unstructured meshes provide a possibility of locally eddy resolving approach. However, a question arises on how to select the resolution, and how mesh variability may affect the eddy dynamics. We discuss a set of questions related to this topic showing that (i) the observed variability and the information on the behavior of the Rossby radius can be one of the criteria helping in mesh design and that (ii) there might be a delayed turbulence development downstream into a high-resolution domain. The latter means that the size of refined patches has to be sufficiently large to simulate the unbiased eddy dynamics. As resolution is increasing, the resolved eddy dynamics may contain a substantial ageostrophic component which may lead to a noisy signal in the vertical velocity on the mesh patches where the resolution is varied. The appearance of this noise depends on the details of discretization. Variable resolution also leads to a question how to combine the locally resolved eddy dynamics with the parameterized one over the coarse part. In a more broad context, even locally eddy-resolving global meshes are already large and approach in size the eddy-permitting and eddy-resolving meshes of global regular models (from 1/4 degree or finer, or 1M or more surface vertices), which implies massively parallel implementations. Our experience with FESOM1.4 shows that because of good parallel scalability the throughput (simulated model years/per day) reached on large meshes is very competitive to (not worse than) that shown by regular-mesh models, with only a moderately increased demand on computational resources. This in a way changes the message to the community on the numerical efficiency of unstructured-mesh models for global ocean applications: these models, especially the new finite-volume developments (MPAS, FESOM2, ICON), can be nearly as fast as the regular-mesh models in terms of their throughput.

Eddy

Rossby number

Ocean dynamics

Large-Eddy Simulation

Source

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Simulating Sea‐Ice Deformation in Viscous‐Plastic Sea‐Ice Models With CD‐Grids

Journal of Advances in Modeling Earth Systems (2023)

Carolin Mehlmann Giacomo Capodaglio Sergey Danilov

Abstract Linear kinematic features (LKFs) are found everywhere in the Arctic sea‐ice cover. They are strongly localized deformations often associated with the formation of leads and pressure ridges. In viscous‐plastic (VP) sea‐ice models, the simulation of LKFs depends on several factors such as the grid resolution, the numerical solver convergence, and the placement of the variables on the mesh. In this study, we compare two recently proposed discretization with a CD‐grid placement with respect to their ability to reproduce LKFs. The first (CD1) is based on a nonconforming finite element discretization, whereas the second (CD2) uses a conforming subgrid discretization. To analyze their resolution properties, we evaluate runs from different models (e.g., FESOM, MPAS) on a benchmark problem using quadrilateral, hexagonal and triangular meshes. Our findings show that the CD1 setup simulates more deformation structure than the CD2 setup. This highlights the importance of the type of spatial discretization for the simulation of LKFs. Due to the higher number of degrees of freedom, both CD‐grids resolve more LKFs than traditional A, B, and C‐grids at fixed mesh level. This is an advantage of the CD‐grid approach, as high spatial mesh resolution is needed in VP sea‐ice models to simulate LKFs.

Quadrilateral

Solver

10.1029/2023ms003696

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Citations (2)

Simulating oceanic mesoscale eddy dynamics: A comparison of novel parameterizations and energy diagnostics and their impact on the global ocean circulation

Stephan Juricke Sergey Danilov Marcel Oliver Anton A. Kutsenko Kai Bellinghausen

In this study, we present a variety of parameterizations for simulating ocean eddy dynamics including novel viscous and kinetic energy backscatter closures. Their effect is analyzed using new diagnostics that allow for application on unstructured meshes.Ocean mesoscale eddy dynamics play a crucial role for large-scale ocean currents as well as for the variability in the ocean and climate. The interactions between eddies and the mean flow affect strength, position and variations of ocean currents. Mesoscale eddies have a substantial impact on oceanic heat transport and the coupling between the atmosphere and ocean. However, at so-called eddy-permitting model resolutions around ¼°, eddy kinetic energy and variability is often substantially underestimated due to excessive dissipation of energy. Despite ever-increasing model resolutions, eddy-permitting simulations will still be used in uncoupled and coupled climate and Earth system simulations for years to come.To improve the presentation of eddy dynamics in such resolution regimes, we present and systematically compare a set of viscous and kinetic energy backscatter parameterization with different complexity. These schemes are implemented in the unstructured grid, finite volume ocean model FESOM2 and tested in both idealized channel and global ocean simulations. We show that kinetic energy backscatter and adjusted viscosity parameterizations can alleviate some of the substantial eddy related biases, for example biases in sea surface height variability, mean currents and in water mass properties. We then further analyze the effect of these schemes on energy and dissipation spectra using new diagnostics that can be extended to the unstructured grid used by FESOM2. The rigorous intercomparison allows to make informed decisions on which schemes are the most suitable for a given application, considering the complexity of the schemes, their computational costs, their adaptability to various model resolutions and any simulation improvements related to a specific scheme. We will show that novel viscous and kinetic energy backscatter schemes outperform previously used, classical viscous closures. Furthermore, when compared to higher resolution simulations, they are computationally less expensive but achieve similar results.

Eddy

Ocean dynamics

Sea-surface height

Large-Eddy Simulation

10.5194/egusphere-egu23-15746

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Cloud-based framework for inter-comparing submesoscale permitting realistic ocean models

Takaya Uchida Julien Le Sommer Charles R. Stern Ryan Abernathey Chris Holdgraf

Abstract. With the increase in computational power, ocean models with kilometer-scale resolution have emerged over the last decade. These models have been used for quantifying the energetic exchanges between spatial scales, informing the design of eddy parametrizations and preparing observing networks. The increase in resolution, however, has drastically increased the size of model outputs, making it difficult to transfer and analyze the data. Nonetheless, it is of primary importance to assess more systematically the realism of these models. Here, we showcase a cloud-based analysis framework proposed by the Pangeo Project that aims to tackle such distribution and analysis challenges. We analyze the output of eight submesoscale-permitting simulations, all on the cloud, for a crossover region of the upcoming Surface Water and Ocean Topography (SWOT) altimeter mission near the Gulf Stream separation. The models used in this study are run with the NEMO, CROCO, MITgcm, HYCOM, FESOM and FIO-COM code bases. The cloud-based analysis framework: i) minimizes the cost of duplicating and storing ghost copies of data, and ii) allows for seamless sharing of analysis results amongst collaborators. We describe the framework and provide example analyses (e.g., sea-surface height variability, submesoscale vertical buoyancy fluxes, and comparison to predictions from the mixed-layer instability parametrization). Basin-to-global scale, submesoscale-permitting models are still at their early stage of development; their cost and carbon footprints are also rather large. It would, therefore, benefit the community to document the different model configurations for future best practices. We also argue that an emphasis on data analysis strategies would be crucial for improving the models themselves.

Parametrization (atmospheric modeling)

SWOT Analysis

10.5194/gmd-2022-27

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Citations (1)

Multi-resolution simulations with the AWI Climate Model (AWI-CM)

Thomas Rackow Tido Semmler Dmitry Sidorenko Helge Goessling Dmitry Sein

The recently established AWI Climate Model (AWI-CM), a coupled configuration of the Finite Element Sea Ice-Ocean Model (FESOM) with the atmospheric model ECHAM6, uses a novel multi-resolution approach: Its ocean component builds on a finite element dynamical core supporting unstructured triangular surface grids, allowing to distribute the grid points in a flexible manner. This allows to concentrate resolution in dynamically important regions, with a continuous transition zone to the coarser resolution in other areas. The model is an ideal tool to study the influence of explicit resolution of smaller scales in dedicated experiments. The unique – spatially seamless – approach might also be of benefit when it comes to temporally seamless prediction, bridging the gap between numerical weather prediction and climate models. A first benchmark set-up of AWI-CM with moderate resolution in the atmosphere (T63) and 25km in key ocean areas, e.g. around the equator, achieved a similar overall simulation performance in a long control simulation compared to well-established CMIP5 models. In particular, the (isotropically) increased equatorial resolution considerably increased the realism of TIW activity and ENSO-related variability compared to standard resolutions. The potential of AWI-CM is further exploited within the EU project PRIMAVERA in the HighResMIP of CMIP6, where we plan to contribute simulations with eddy-resolving resolutions (1/12° or 9-10 km) in key areas of the global ocean, such as the Gulf Stream-North Atlantic Current region, the Agulhas retroflection zone, or the Arctic basin. First simulations show distinct improvements with respect to the development of deep temperature and salinity biases in the North Atlantic Ocean and an overall improvement of surface biases. At even higher resolutions of 4.5 km locally in the Arctic, linear kinematic features emerge in the simulated sea ice distribution with potentially strong impacts on air-sea fluxes in the coupled system. Although the tested set-ups are computationally very demanding (with numbers of grid points comparable to a regular 0.25° grid), the throughput is high at about 8 simulated years per day because of high scalability. In addition, we are about to finish the development of a finite volume version of the ocean model code (FESOM 2). It is already faster than the original FESOM version by a factor of two to three, which will further enlarge the set of computationally feasible applications.

Source

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Basal melting under an ice shelf: A sensitivity study

Qiang Wang Sergey Danilov Thomas Jung

Basal (medicine)

Source

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Sea Ice Numerical VP-Comparison Benchmark

Carolin Mehlmann Sergey Danilov Martin Lösch Jean‐François Lemieux Nils Hutter

Benchmark (surveying)

10.17632/kj58y3sdtk.1

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Citations (4)

Split-explicit external mode solver in finite volume sea ice ocean model FESOM2

Tridib Banerjee Patrick Scholz Sergey Danilov Knut Klingbeil Dmitry Sidorenko

Abstract. A novel split-explicit (SE) external mode solver for the Finite volumE Sea ice–Ocean Model (FESOM2) and its sub-versions (example 2.5) is presented. It is compared with the semi-implicit (SI) solver currently used in FESOM2. The split-explicit solver utilizes a dissipative asynchronous (forward–backward) time-stepping scheme. Its implementation with Arbitrary Lagrangian-Eulerian vertical coordinates like Z-star (Z ∗) and Z-tilde (Z˜) is explored. The comparisons are performed through multiple test cases involving idealized and realistic global simulations. The SE solver demonstrates lower phase errors and dissipation, but maintain a simulated mean ocean state very similar to the SI solver. The SE solver is also shown to possess better run-time performance and parallel scalability across all tested workloads.

Solver

10.5194/gmd-2023-208

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