Agnieszka Herman

Agnieszka Herman
Institute of Oceanology Polish Academy of Sciences · Department of Physical Oceanography

PhD

About

88
Publications
20,304
Reads
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867
Citations
Introduction
Agnieszka Herman currently works at the Institute of Oceanology, Polish Academy of Scienes, in Sopot, Poland. Agnieszka does research in Sea Ice, Oceanography, Meteorology and Applied Mathematics.
Additional affiliations
February 2022 - present
Institute of Oceanology Polish Academy of Sciences
Position
  • Professor (Associate)
March 2015 - January 2022
University of Gdansk
Position
  • Professor (Associate)
Education
October 1999 - November 2003
University of Gdansk
Field of study
October 1995 - June 1999
University of Gdansk
Field of study

Publications

Publications (88)
Article
Full-text available
This paper presents theoretical foundations, numerical implementation and examples of application of the two-dimensional Discrete-Element bonded-particle Sea Ice model – DESIgn. In the model, sea ice is represented as an assemblage of objects of two types: disk-shaped “grains” and semi-elastic bonds connecting them. Grains move on the sea surface u...
Article
Full-text available
This paper presents the analysis of floe-size distribution (FSD) data obtained in laboratory experiments of ice breaking by waves. The experiments, performed at the Large Ice Model Basin (LIMB) of the Hamburg Ship Model Basin (Hamburgische Schiffbau-Versuchsanstalt, HSVA), consisted of a number of tests in which an initially continuous, uniform ice...
Article
Full-text available
The energy of water waves propagating through sea ice is attenuated due to non-dissipative (scattering) and dissipative processes. The nature of those processes and their contribution to attenuation depends on wave characteristics and ice properties and is usually difficult (or impossible) to determine from limited observations available. Therefore...
Article
Full-text available
This work analyses laboratory observations of wave energy attenuation in fragmented sea ice cover composed of interacting, colliding floes. The experiment, performed in a large (72 m long) ice tank, includes several groups of tests in which regular, unidirectional, small-amplitude waves of different periods were run through floating ice with differ...
Article
Dissipation within the turbulent boundary layer under sea ice is one of many processes contributing to wave energy attenuation in ice-covered seas. Although recent observations suggest that the contribution of that process to the total energy dissipation is significant, its parameterizations used in spectral wave models are based on fairly crude, h...
Article
Full-text available
One contribution of 17 to a theme issue 'Theory, modelling and observations of marginal ice zone dynamics: multidisciplinary perspectives and outlooks'. Sea ice in the marginal ice zone (MIZ) consists of relatively small floes with a wide size span. In response to oceanic and atmospheric forcing, it behaves as an approximately two-dimensional, hig...
Preprint
Full-text available
Surface waters of the oceans carry large amounts of material, including sediment grains, plankton organisms, ice crystals, as well as pollutants, e.g., oil and plastic. Transport and spatio-temporal distribution of that material depend on its properties and on the dynamical processes in the ocean mixed layer-currents, waves, turbulence, and convect...
Conference Paper
Antarctic coastal polynyas have been coined as "ice factories" because of the high ice formation rates under the influence of cold katabatic winds from the Antarctic continent. Ice forms at high rates in the open water areas created by the wind-blown advection of the new ice formed. During the May 2017 PIPERS cruise into Terra Nova Bay (TNB) in the...
Preprint
Sea ice in the marginal ice zone (MIZ) consists of relatively small floes with a wide size span. In response to oceanic and atmospheric forcing it behaves as an approximately two-dimensional, highly polydisperse granular material. The established viscous-plastic rheologies used in continuum sea ice models are not suitable for the MIZ; the collision...
Article
Full-text available
The floe size distribution (FSD) is an important characteristics of sea ice, influencing several physical processes that take place in the oceanic and atmospheric boundary layers under/over sea ice, as well as within sea ice itself. Through complex feedback loops involving those processes, FSD might modify the short-term and seasonal evolution of t...
Preprint
Full-text available
The floe size distribution (FSD) is an important characteristics of sea ice, influencing several physical processes that take place in the oceanic and atmospheric boundary layers under/over sea ice, as well as within sea ice itself. Through complex feedback loops involving those processes, FSD might modify the short-term and seasonal evolution of t...
Article
Full-text available
The Hailuoto Atmospheric Observations over Sea ice (HAOS) campaign took place at the western-most point of Hailuoto island (Finland) between 27 February and 2 March 2020. The aim of the campaign was to obtain atmospheric boundary layer (ABL) observations over seasonal sea ice in the Bay of Bothnia. Throughout 4 d, both fixed-wing and quad-propeller...
Article
Full-text available
Frazil and grease ice forms in the ocean mixed layer (OML) during highly turbulent conditions (strong wind, large waves) accompanied by intense heat loss to the atmosphere. Three main velocity scales that shape the complex, three-dimensional (3D) OML dynamics under those conditions are the friction velocity u* at the ocean-atmosphere interface, the...
Preprint
Full-text available
The Hailuoto Atmospheric Observations over Sea ice (HAOS) campaign took place at the westernmost point of Hailuoto island (Finland) between 27 February and 2 March 2020. The aim of the campaign was to obtain atmospheric boundary layer (ABL) observations over seasonal sea ice in the Bay of Bothnia. Throughout 4 days both fixed-wing and quad-propelle...
Preprint
[revised manuscript submitted to Journal of Physical Oceanography; https://arxiv.org/abs/2007.14656] Dissipation within the turbulent boundary layer under sea ice is one of many processes contributing to wave energy attenuation in ice-covered seas. Although recent observations suggest that the contribution of that process to the total energy dissi...
Article
Full-text available
Frazil and grease ice forms in the ocean mixed layer (OML) during highly turbulent conditions (strong wind, large waves) accompanied by intense heat loss to the atmosphere. Three main velocity scales that shape the complex, three-dimensional OML dynamics under those conditions are: the friction velocity u* at the ocean--atmosphere interface, the ve...
Article
Full-text available
Sea ice fragmentation results in the transformation of the surface from relatively homogeneous to highly heterogeneous. Atmospheric boundary layer (ABL) rapidly responds to those changes through a range of processes which are poorly understood and not parametrized in numerical weather prediction (NWP) models. The aim of this work is to increase our...
Article
Full-text available
The energy of water waves propagating through sea ice is attenuated due to nondissipative (scattering) and dissipative processes. The nature of those processes and their contribution to attenuation depends on wave characteristics and ice properties, and is usually difficult (or impossible) to determine from limited observations available. Therefore...
Article
Full-text available
This work analyzes laboratory observations of wave energy attenuation in fragmented sea ice cover composed of interacting, colliding floes. The experiment, performed in a large (72 m long) ice tank, includes several groups of tests in which regular, unidirectional, small-amplitude waves of different periods were run through floating ice with differ...
Preprint
Full-text available
The energy of water waves propagating through sea ice is attenuated due to nondissipative (scattering) and dissipative processes. The nature of those processes and their contribution to attenuation depends on wave characteristics and ice properties, and is usually difficult (or impossible) to determine from limited observations available. Therefore...
Preprint
Full-text available
This work analyzes laboratory observations of wave energy attenuation in fragmented sea ice cover composed of interacting, colliding floes. The experiment, performed in a large (72 m long) ice tank, includes several groups of tests in which regular, unidirectional, small-amplitude waves of different periods were run through floating ice with differ...
Article
Full-text available
The objective of this research is to determine the impact of waves on the segregation of sediment within the area of its supply in the context of meteorological conditions. The research was conducted on a 4 km section of the shore of Calypsostranda (Bellsund, West Spitsbergen), shaped by waves such as swell, wind waves, and tides. Particular attent...
Article
In this study, the third-generation spectral wave model Simulating WAves Nearshore (SWAN) is applied to an analysis of wind wave conditions in Hornsund, a relatively small fjord in the southwestern part of Spitsbergen (Svalbard Archipelago). The model is run on a series of three nested grids with increasing spatial resolution. Wave energy spectra f...
Article
Full-text available
Among many mechanisms potentially contributing to wave energy attenuation in sea ice are wave-induced ice floe collisions. At present, little is known about collision patterns and their phase-averaged effects under different combinations of sea ice properties (ice thickness, floe size, etc.) and wave forcing (wavelength and steepness). The existing...
Preprint
Full-text available
Key Points: • Wave-induced surge motion of large ice floes can be described by a simple model with proper forcing, integrated over floe volume/area. • Different combinations of model parameters produce different (regular or irregular) collision patterns, with short or prolonged contact. • Stress in the ice and other phase-averaged effects of coll...
Preprint
Full-text available
In this study, the third-generation spectral wave model Simulating WAves Nearshore (SWAN) is applied to an analysis of wind wave conditions in Horn-sund, a relatively small fjord in the southwestern part of Spitsbergen (Sval-bard Archipelago). The model is run on a series of three nested grids with increasing spatial resolution. Wave energy spectra...
Article
Full-text available
The response of the atmospheric boundary layer (ABL) to subgrid-scale variations of sea ice properties and fracturing is poorly understood and not taken into account in mesoscale Numerical Weather Prediction (NWP) model parametrizations. In this paper we analyze three-dimensional air circulation within the ABL over fragmented sea ice. A series of i...
Article
Full-text available
Waves are the key phenomenon directly influencing coastal morphodynamics. Facing insufficient observations, wind wave climate of the west coast of Spitsbergen can be characterized on the basis of the modelled data. Here we have used the results of spectral wave models: Wave Watch III (WW3) hindcast and WAM in ERA-interim (ERAi) reanalysis. We have...
Article
Full-text available
In this paper, a coupled sea ice–wave model is developed and used to analyze wave-induced stress and breaking in sea ice for a range of wave and ice conditions. The sea ice module is a discrete-element bonded-particle model, in which ice is represented as cuboid grains floating on the water surface that can be connected to their neighbors by elasti...
Article
Full-text available
This paper presents the analysis of floe-size distribution (FSD) data obtained in laboratory experiments of ice breaking by waves. The experiments, performed at the Large Ice Model Basin (LIMB) of the Hamburg Ship Model Basin (Hamburgische Schiffbau-Versuchsanstalt, HSVA), consisted of a number of tests in which an initially continuous, uniform ice...
Poster
Full-text available
The response of the atmospheric boundary layer (ABL) to subgrid-scale variations of sea ice properties and fracturing is poorly understood and not taken into account in mesoscale Numerical Weather Prediction (NWP) models parametrizations. A series of idealized, high-resolution simulations with Weather Research and Forecasting Model is performed for...
Conference Paper
Full-text available
A multi-group investigation was conducted at Hamburgische Schiffbau-Versuchsanstalt GmbH (HSVA) from Oct. 24 to Nov. 11, 2016 under the Hydralab+ Transnational Access project: Loads on Structure and Waves in Ice (LS-WICE). There are four parts to this investigation: wave attenuation/dispersion in broken ice covers, wave-induced ice-floe collisions,...
Conference Paper
Full-text available
A multi-group investigation was conducted at Hamburgische Schiffbau-Versuchsanstalt GmbH (HSVA) from Oct. 24 to Nov. 11, 2016 under the project: Loads on Structure and Waves in Ice (LS-WICE). There are three parts to this investigation: ice fracture under wave actions, wave attenuation/dispersion in broken ice covers, and ice-structure interaction...
Conference Paper
Full-text available
A multi-group investigation was conducted at Hamburgische Schiffbau-Versuchsanstalt GmbH (HSVA) from Oct. 24 to Nov. 11, 2016 under the Hydralab+ Transnational Access project: Loads on Structure and Waves in Ice (LS-WICE). There are three parts to this investigation: ice fracture under wave actions, wave attenuation/dispersion in broken ice covers,...
Article
Full-text available
In this paper, a coupled sea ice–wave model is developed and used to analyze the variability of wave-induced stress and breaking in sea ice. The sea ice module is a discrete-element bonded-particle model, in which ice is represented as cuboid “grains” floating on the water surface that can be connected to their neighbors by elastic “joints”. The jo...
Poster
Full-text available
In mesoscale numerical weather prediction (NWP) models, sea ice cover is typically represented by grid-cell-average ice concentration and thickness. The relevant variables – surface heat and moisture fluxes, roughness, albedo and so on – are calculated as a weighted average of the respective values over sea ice and open water. With typical model re...
Data
The data were collected during the research project "Measurements and numerical modeling of sediment transport and coastal erosion under storm conditions". When you are using these data in any publications and/or presentations, please acknowledge "the Polish Ministry of Science and Higher Education research grant No. 5095/B/P01/2010/38 (Measuremen...
Article
Full-text available
Ocean–atmosphere interactions are complex and extend over a wide range of temporal and spatial scales. Among the key components of these interactions is the ocean–atmosphere (latent and sensible) turbulent heat flux (THF). Here, based on daily optimally-interpolated data from the extratropical Southern Hemisphere (south of 30°S) from a period 1985–...
Article
Full-text available
Intensive development of infrastructure for fast processing of outsized amount of space-borne data enables now to use the satellite data for operational controlling the state of its environment. In our presentation we show some examples of analysis of processes in marine environment which are possible due to satellite data and algorithms of its pro...
Preprint
Full-text available
This paper presents theoretical foundations, numerical implementation and examples of application of a two-dimensional Discrete-Element bonded-particle Sea Ice model DESIgn. In the model, sea ice is represented as an assemblage of objects of two types: disk-shaped "grains", and semi-elastic bonds connecting them. Grains move on the sea surface unde...
Article
Full-text available
Although substantial progress has been made in recent years in research on sheared granular matter, relatively few studies concentrate on the behavior of materials with very strong polydispersity. In this paper, shear deformation of a two-dimensional granular material composed of frictional disk-shaped grains with power-law size distribution is ana...
Article
Full-text available
In this paper, a molecular-dynamics sea-ice model is used to study contact and force networks in fragmented sea ice, composed of separate floes with power-law size distribution. The momentum equations for individual floes, taking into account floe/floe collisions (with Hertzian contact mechanics), are formulated in a way suitable for a computationa...
Article
Full-text available
The temporal variability of the moments of prob-ability distribution functions (pdfs) of total sea ice defor-mation rates in the Arctic is analyzed in the context of the basin-scale wind forcing acting on the ice. The pdfs are es-timated for 594 satellite-derived sea ice deformation maps from 11 winter seasons between 1996/1997 and 2007/2008, provi...
Article
Full-text available
At medium ice concentrations, sea ice consists of separate floes of different sizes interacting with each other through inelastic collisions, in a way similar to two-dimensional polydisperse granular gases. The dynamics of this type of ice cover is poorly understood. In this paper, a molecular-dynamics sea-ice model based on simplified momentum equ...
Article
Full-text available
In seasonally ice-covered seas and along the margins of perennial ice pack, i.e., in regions with medium ice concentrations, the ice cover typically consists of separate floes interacting with each other by inelastic collisions. In this paper, hitherto unexplored analogies between this type of ice cover and two-dimensional granular gases are used t...
Article
Full-text available
In this paper, a numerical dynamic-thermo-dynamic sea-ice model for the Baltic Sea is used to analyze the variability of ice conditions in three winter seasons. The modelling results are validated with station (water temperature) and satellite data (ice concentration) as well as by qualitative comparisons with the Swedish Meteorological and Hydrolo...
Article
Full-text available
On the basis of monthly averaged satellite data, this study examined how the annual cycle of the Baltic Sea surface temperature (SST)varied spatially and temporally during the period 1986-2005.We conclude that there are two main thermal seasons in the Baltic Sea separated only by short transitional periods - spring lastingabout one month, and autum...
Article
Full-text available
Sea-ice floe-size distribution (FSD) in ice-pack covered seas influences many aspects of ocean-atmosphere interactions. However, data concerning FSD in the polar oceans are still sparse and processes shaping the observed FSD properties are poorly understood. Typically, power-law FSDs are assumed although no feasible explanation has been provided ne...
Article
Full-text available
In this paper the wind-wave variability in the tidal basins of the German Wadden Sea is modelled with combined numerical and neural-network (NN) methods. First, the wave propagation and transformation in the study area are modelled with the state-of-the-art third-generation spectral wave model SWAN. The ability of SWAN to accurately reproduce the p...