Open Water Conditions Research Articles

Observation of three-dimensional flow structures and effluent transport around fish cages using a towed ADCP and free-fall multi-parameter profiler

A field campaign was conducted around salmon cages, using a combination of a towed ADCP and a free-fall multi-parameter profiler, in order to investigate flow structures and the possible distribution of effluent materials. Two transect observations showed that hydrographic conditions changed dramatically within 5 days, from highly stratified open water conditions to weak stratification. Three-dimensional observation revealed that flow was blocked behind the cages and that the blockage was reduced as the distance from the cages increased. The flow speed was positively correlated with the intensity of the backscattering signal. The R2 value was high immediately behind the cages and decreased with distance from the cages. The flow time series behind the cages exhibited a k–2 power law spectrum that was consistent with a typical internal wave spectrum. This suggests that eddies shed from the cages were highly influenced by stratification. We estimated the rate of kinetic energy dissipation, , from YODA Profiler data based on the Thorpe scale approach. We also estimated the eddy diffusivity coefficient, . Both and followed a lognormal probability density function. The mean was consistent with a one-dimensional diffusion model assessed from the R2 values of flow speed and backscatter intensity.

Numerical investigation of the rake angle effect on the hydrodynamic performance of propeller in a uniform and nonuniform flow

Marine propeller always operates in the wake of a vehicle (ship, torpedo, submarine) but (due to the high computational cost of simulating vehicle and propeller simultaneously) to investigate the propeller geometric parameters, simulations are usually performed in open-water conditions. In this article, using the computational fluid dynamics method with the control volume approach, the effect of the rake angle on the propeller performance and formation of cavitation in the uniform flow (open water) and the nonuniform flow (wake flow) was investigated. In the nonuniform condition, the array of plates was used to simulate wake at upstream propeller. For uniform flow, steady solution scheme was adopted and for nonuniform flow unsteady solution scheme was adopted, and a moving mesh zone was generated around the propeller. To simulate cavitation a multiphase mixture flow, the Reynolds-averaged Navier–Stokes method was used and modeled by Schnerr Sauer's cavitation model. First, the E779a propeller model for numerical validation in the uniform flow and nonuniform flow was investigated. Numerical results were compared with the experimental result, and there was a good agreement between volume of the cavity, thrust, and torque coefficients. To study the effect of rake angle on the performance of B-series propellers, four models with different rake angles were modeled, and simulation was investigated behind the wake. The results of thrust, torque coefficients, and cavitation volume according to the flow parameters and cavitation number were presented as graphs. The results reveals that in the uniform flow, the rake angle has no significant effect on the propeller performance, but behind the wake flow, increase of rake causes to reduce the force applied to the propeller blades, cavitation volume, and pressure fluctuations on the propeller.

VESSEL-INDUCED SURGE MODEL VALIDATION IN A COMPLEX HARBOR USING FIELD MEASUREMENTS AND AIS DATA

Large ships moving in narrow waterways generate complex hydrodynamic phenomena, which can cause extreme forces and moments on berthed vessels, and damage shoreline structures and marine habitat. Deep-draft vessels can generate complex phenomena such as bow solitary waves, broken supercritical bore waves, and ship-induced harbor seiche/oscillations. Particular focus is paid in the present paper to simulation and validation of the Vessel Hydrodynamics Longwave Unsteady (VH-LU) modeling system (Fenical et al. 2006) for these complex hydrodynamic phenomena, in particular sloshing and resonance of vessel-induced waves in the complex harbor of Port Canaveral, FL. This paper summarizes two field measurement campaigns and utilization of high-resolution AIS data to provide detailed input for model validation. Analysis indicates that the modeling system is able to reproduce water level oscillations generated by individual vessels, oscillation interactions within the harbor, and interactions between separate basins in the harbor over time. Previous publications have provided limited information on validations performed with the VH-LU modeling system (e.g. Fenical et al. 2011). The model has been shown to accurately reproduce hydrodynamics and berthed vessel forces on tankers in open water conditions, hydrodynamics and loads on berthed Panamax container ships against a vertical quay wall, and supercritical flow and broken bore formation and propagation. This paper will summarize the complete range of model validations with the highest-quality openly available laboratory data, and provide recommendations for future studies and research based on observed needs from practical applications.

A method for modeling of the consequences of super-continuous accidents on oil production objects in the Arctic region

The elimination of the oil spill at the DWH (Deep-Water Horizon) well in the Gulf of Mexico took place in almost ideal hydrometeorological conditions, which did not create serious difficulties for the operation of the response forces and means. There is a problem of assessing the possible consequences of an accident of this scale in the Arctic conditions. The simulation method of a long-lasting oil spill in the ice infested region is considered. A new model for the spreading of an elementary spill (ES) is described. A total oil spill is constructed as superposition of a number of an elementary spill. Taking into account the transport of oil by drifting ice, the potential impact of spills on vulnerable areas in the sea and coasts can reach distance of hundreds and thousands of kilometers. The distribution of ES on the surface of ice-free water is limited by the lifetime, depending on the properties of oil and regional hydro-meteorological conditions and elongated by the duration of the ice capture. The paper presents examples of estimating the lifetime of an ongoing oil spill in open water conditions based on the analysis of wind conditions in the area of interest by long-term series of meteorological reanalysis. On the basis of the analysis, an efficient computational algorithm to estimate the probability of a long-lasting oil spills impact on specially protected natural areas is constructed.

An advanced joint time-frequency analysis procedure to study cavitation-induced noise by using standard series propeller data

Underwater noise has attracted significant amount of interest in the last decade because of its potential impact on marine fauna. Commercial shipping is one of the major contributors. Amongst various sources on-board, cavitation dominates the overall radiated noise levels beyond its inception. Besides its significance, the mechanisms driving cavitation related noise and frequency regions that certain cavitation dynamics contribute into are not studied sufficiently. To address this gap in the literature, a study has been conducted to provide means of a plausible propeller cavitation noise prediction method and to provide enhanced insight to the noise creating mechanisms of cavitation by applying appropriate signal processing methods.Within this framework this study presents an advanced joint time-frequency analysis procedure to study cavitation-induced noise by using standard series propeller data. Systematic cavitation tunnel test are conducted with 6 members of the Meridian Standard propeller series that are carefully chosen to study the influence of major propeller design parameters such as Blade Area Ratio (BAR), Pitch to Diameter (P/D) ratio and blade number. Moreover, these propellers are tested behind systematically varied wake inflows reproduced by wake screens in addition to the open water conditions. Synchronized pressure pulse and noise measurements in combination with high-speed cavitation observations are then utilized to develop an advanced cavitation dynamics analysis tool to provide better insight into cavitation-induced noise. The analysis of the measurements has shown the significance of the cavitation on radiated noise levels and the impact of different cavitation dynamics in certain frequency regions.

Measurements of underwater noise north of Spitsbergen using deep-sea recorders

This paper presents results from year-long passive acoustic recordings in the seasonally ice-covered ocean north of Spitsbergen (Svalbard archipelago) from July 2016 to June 2017. Two moorings were deployed by FFI, each with an AMAR Ultra Deep acoustic recorder (JASCO Applied Sciences) equipped with a single hydrophone. The moorings were deployed and retrieved during open-water conditions and remained during periods of partially to near fully ice-covered conditions. We present results from analysis of the acoustic data for ambient noise spectra and statistics, and discuss characteristics of the spectra in relation to environmental factors including ice cover, wind and ocean waves. Seasonal noise spectra are compared with historic measurements from the eastern Arctic. Components of the sound field including transients due to ice, marine mammals, and anthropogenic noise will also be discussed.

Variability and Redistribution of Heat in the Atlantic Water Boundary Current North of Svalbard

AbstractWe quantify Atlantic Water heat loss north of Svalbard using year‐long hydrographic and current records from three moorings deployed across the Svalbard Branch of the Atlantic Water boundary current in 2012–2013. The boundary current loses annually on average 16 W m−2 during the eastward propagation along the upper continental slope. The largest vertical fluxes of >100 W m−2 occur episodically in autumn and early winter. Episodes of sea ice imported from the north in November 2012 and February 2013 coincided with large ocean‐to‐ice heat fluxes, which effectively melted the ice and sustained open water conditions in the middle of the Arctic winter. Between March and early July 2013, a persistent ice cover‐modulated air‐sea fluxes. Melting sea ice at the start of the winter initiates a cold, up to 100‐m‐deep halocline separating the ice cover from the warm Atlantic Water. Semidiurnal tides dominate the energy over the upper part of the slope. The vertical tidal structure depends on stratification and varies seasonally, with the potential to contribute to vertical fluxes with shear‐driven mixing. Further processes impacting the heat budget include lateral heat loss due to mesoscale eddies, and modest and negligible contributions of Ekman pumping and shelf break upwelling, respectively. The continental slope north of Svalbard is a key example regarding the role of ocean heat for the sea ice cover. Our study underlines the complexity of the ocean's heat budget that is sensitive to the balance between oceanic heat advection, vertical fluxes, air‐sea interaction, and the sea ice cover.

Seasonal changes in sulfur biogeochemistry of a dilute, dimictic Arctic lake: Implications for paired sulfur isotope records from ancient oceans

Calibration of ancient marine sulfate levels has been done largely using experimental studies of the kinetic isotope effect associated with microbial sulfate reduction and work from modern ocean basins or high-sulfate lakes that are largely restricted and meromictic. The sulfur isotope record of sulfates and sulfides from sedimentary sequences have been used to reconstruct sulfate levels throughout the geologic record and indicate that sulfate concentrations were low relative to modern oceans (28 mM) for most of Earth's history. Despite the higher potential for modern low-sulfate systems to be a better analog for ancient oceans, there are few sulfur isotope studies that have been carried out in these environments. Here, we present δ34S systematics of a modern low-sulfate (~330–600 μM) euxinic lake on the ice-free margin of southwestern Greenland. We find large isotope fractionations (>20‰) between water column sulfate and sulfides, with this fractionation increasing from 23.9‰ during open-water conditions to 42.0‰ under annual ice-cover. While these large kinetic isotope effects associated with microbial sulfate reduction (εSR) are expressed in the water column of this lake, the underlying sedimentary sulfides preserve a notably smaller range of δ34S values (13.0–26.6‰). Geochemical modeling of our data suggests that the δ34S of water column sulfate and sulfides, along with sedimentary sulfides are primarily controlled by εSR and a reservoir effect established under strong thermal stratification during open-water conditions. Under ice-covered conditions εSR appears to be the dominant control on δ34S values, and when combining both seasonal data sets εSR increases as a function of sulfate levels in the lake. Sulfur isotopic data presented here highlight the complexity of seasonal biogeochemical cycling of sulfur in low-sulfate systems, and how system openness affects δ34S fractionations in modern euxinic depositional environments. Specifically, a reservoir effect is only documented in the water column δ34S data under open-water conditions, however a reservoir effect is apparent from sedimentary sulfides under both ice-cover and open-water conditions due to time averaging pyrite δ34S values. Our results add to the growing body of work on modern low-sulfate systems to help further constrain the use of ancient δ34S records for paleoenvironmental reconstructions.

Numerical simulation of the cavitating KP505 propeller working in open water conditions

The present paper proposes a numerical study, fully experimentally validated, usable for the optimal design of the naval propulsion features. The marine propeller KP 505 is a representative propeller geometry with experimental available detailed, so this is chosen as a reference for probing the accuracy of the present study. Data obtained from this model is extensively used to provide validation for unsteady RANS calculations, with specific interest in predicting tip-vortex flow characteristics. The method used is based on the fundamental conservation equations. Since DNS modeling requires excessive computational effort due to the very dense discretization of computational domain and very limited time step, it is assumed that the influence of turbulence on the flow is derived with sufficient accuracy based on the averaged flow parameters. In the present computations the EASM model is applied, which proved to be a stable and accurate model. The computed overall accuracy of the proposed model is validated by an extensive comparison with experimental data from the free running tests performed by NMRI Tokyo and HSVA Hamburg. The main features of the flow field, with particular attention to the vortical structures detached from the blades are comparatively presented in an attempt to validate the technique proposed.

Improved surface soil moisture anomalies from Fengyun-3B over the Jiangxi province of the People’s Republic of China

ABSTRACTThis study develops a data-driven modification scheme for a commonly used soil moisture retrieval algorithm by introducing a vegetation density-related single scattering albedo based on in situ and Fengyun-3B passive microwave observations. The Jiangxi province in China’s mainland is one of the most challenging regions for soil moisture retrievals due to its complex topography, open water, and vegetation conditions. However, it has a very dense in situ soil moisture observation network which makes it a suitable test-bed to examine the performance of the modification scheme. The development of this new scheme consists of two steps. In a first step, the model is initialized using the most recently developed algorithm configuration. In the second step, these initial outcomes are used as input to determine the vegetation density related single scattering albedo which is solely based on observational data and used as the final algorithm configuration over our study area. We start by comparing the two most recent algorithm configurations against the in situ soil moisture network and demonstrate an overall improvement in terms of correlations coefficient for the most recent version. Then, the observational data- driven modification scheme was proposed and evaluated against the in situ soil moisture network with further improvements after its implementation. We furthermore applied the vegetation density-based scattering albedo in soil moisture retrievals over all grid cells in Jiangxi, and found that soil moisture data with the newly developed configuration significantly improved (up to 30%) compared to the preceding algorithm configurations. The two existing algorithm configurations were also evaluated over all grid cells and all results indicate consistent improvements between the successive algorithm versions.

Historical watershed stressors for the Laurentian Great Lakes.

This report provides a detailed set of historical stressor data for 60 watersheds comprising the Laurentian Great Lakes basin. Archival records were transcribed from public records to create quantitative data on human activities: population, mining, deforestation, and agriculture. Yearly records of stressors are provided from 1780 through 2010. These data may be used to track historical impacts on Great Lakes coastal and open water conditions. They may further be used to examine corresponding effects on response variables such as biological communities quantified during monitoring and palaeoecological programmes.Open Practices This article has earned an Open Data badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. The data is available at https://doi.org/10.1594/PANGAEA.885879. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki.

Experimental Validation of Fluid–Structure Interaction Computations of Flexible Composite Propellers in Open Water Conditions Using BEM-FEM and RANS-FEM Methods

In the past several decades, many papers have been published on fluid–structure coupled calculations to analyse the hydro-elastic response of flexible (composite) propellers. The flow is usually modelled either by the Navier–Stokes equations or as a potential flow, by assuming an irrotational flow. Phenomena as separation of the flow, flow transition, boundary layer build-up and vorticity dynamics are not captured in a non-viscous potential flow. Nevertheless, potential flow based methods have been shown to be powerful methods to resolve the hydrodynamics of propellers. With the upcoming interest in flexible (composite) propellers, a valid question is what the consequences of the potential flow simplifications are with regard to the coupled fluid–structure analyses of these types of propellers. This question has been addressed in the following way: calculations and experiments were conducted for uniform flows only, with a propeller geometry that challenges the potential flow model due to its sensitivity to leading edge vortex separation. Calculations were performed on the undeformed propeller geometry with a Reynolds-averaged-Navier–Stokes (RANS) solver and a boundary element method (BEM). These calculations show some typical differences between the RANS and BEM results. The flexible propeller responses were predicted by coupled calculations between BEM and finite element method (FEM) and RANS and FEM. The applied methodologies are briefly described. Results obtained from both calculation methods have been compared to experimental results obtained from blade deformation measurements in a cavitation tunnel. The results show that, even for the extreme cases, promising results have been obtained with the BEM-FEM coupling. The BEM-FEM calculated responses are consistent with the RANS-FEM results.

Computing under-ice discharge: A proof-of-concept using hydroacoustics and the Probability Concept

Under-ice discharge is estimated using open-water reference hydrographs; however, the ratings for ice-affected sites are generally qualified as poor. The U.S. Geological Survey (USGS), in collaboration with the Colorado Water Conservation Board, conducted a proof-of-concept to develop an alternative method for computing under-ice discharge using hydroacoustics and the Probability Concept.The study site was located south of Minturn, Colorado (CO), USA, and was selected because of (1) its proximity to the existing USGS streamgage 09064600 Eagle River near Minturn, CO, and (2) its ease-of-access to verify discharge using a variety of conventional methods. From late September 2014 to early March 2015, hydraulic conditions varied from open water to under ice. These temporal changes led to variations in water depth and velocity. Hydroacoustics (tethered and uplooking acoustic Doppler current profilers and acoustic Doppler velocimeters) were deployed to measure the vertical-velocity profile at a singularly important vertical of the channel-cross section. Because the velocity profile was non-standard and cannot be characterized using a Power Law or Log Law, velocity data were analyzed using the Probability Concept, which is a probabilistic formulation of the velocity distribution. The Probability Concept-derived discharge was compared to conventional methods including stage-discharge and index-velocity ratings and concurrent field measurements; each is complicated by the dynamics of ice formation, pressure influences on stage measurements, and variations in cross-sectional area due to ice formation.No particular discharge method was assigned as truth. Rather one statistical metric (Kolmogorov-Smirnov; KS), agreement plots, and concurrent measurements provided a measure of comparability between various methods. Regardless of the method employed, comparisons between each method revealed encouraging results depending on the flow conditions and the absence or presence of ice cover.For example, during lower discharges dominated by under-ice and transition (intermittent open-water and under-ice) conditions, the KS metric suggests there is not sufficient information to reject the null hypothesis and implies that the Probability Concept and index-velocity rating represent similar distributions. During high-flow, open-water conditions, the comparisons are less definitive; therefore, it is important that the appropriate analytical method and instrumentation be selected. Six conventional discharge measurements were collected concurrently with Probability Concept-derived discharges with percent differences (%) of −9.0%, −21%, −8.6%, 17.8%, 3.6%, and −2.3%.This proof-of-concept demonstrates that riverine discharges can be computed using the Probability Concept for a range of hydraulic extremes (variations in discharge, open-water and under-ice conditions) immediately after the siting phase is complete, which typically requires one day. Computing real-time discharges is particularly important at sites, where (1) new streamgages are planned, (2) river hydraulics are complex, and (3) shifts in the stage-discharge rating are needed to correct the streamflow record. Use of the Probability Concept does not preclude the need to maintain a stage-area relation. Both the Probability Concept and index-velocity rating offer water-resource managers and decision makers alternatives for computing real-time discharge for open-water and under-ice conditions.

The influence of the bow design on structural response due to ice loading

ABSTRACTThe optimum bow shape for an ice-going vessel in ice conditions is different to open water conditions and research about the influence of the bow shape on the structural response due to ice loading and resistance is required. A framework is developed to study the functional relationship between the bow shape and the structural response for ice-going bows in MATLAB. The structural dimensions are optimised by an automatic link to a parametric finite element model in ANSYS Mechanical. Both the buttock angle and the average waterline angle should be as small as possible to reduce the channel ice resistance. When changing the bow shape angles along an iso-resistance curve, the design pressure is constant and thus the structural response according to the DNVGL rules. It is found that the maximum stress in plates of the bow increases by reducing the average waterline angle while keeping the structural design constant.

Time-lapse imagery of Adélie penguins reveals differential winter strategies and breeding site occupation.

Polar seabirds adopt different over-wintering strategies to survive and build condition during the critical winter period. Penguin species either reside at the colony during the winter months or migrate long distances. Tracking studies and survey methods have revealed differences in winter migration routes among penguin species and colonies, dependent on both biotic and abiotic factors present. However, scan sampling methods are rarely used to reveal non-breeding behaviors during winter and little is known about presence at the colony site over this period. Here we show that Adélie penguins on the Yalour Islands in the Western Antarctic Peninsula (WAP) are present year-round at the colony and undergo a mid-winter peak in abundance during winter. We found a negative relationship between daylight hours and penguin abundance when either open water or compact ice conditions were present, suggesting that penguins return to the breeding colony when visibility is lowest for at-sea foraging and when either extreme low or high levels of sea ice exist offshore. In contrast, Adélie penguins breeding in East Antarctica were not observed at the colonies during winter, suggesting that Adélie penguins undergo differential winter strategies in the marginal ice zone on the WAP compared to those in East Antarctica. These results demonstrate that cameras can successfully monitor wildlife year-round in areas that are largely inaccessible during winter.

Numerical simulation of turbulent flow around the dtmb4119 propeller in open water conditions

In this study, ANSYS-FLUENT packages are employed to simulate the turbulent flow around DTMB4119 propeller in open water conditions. In order to form a mesh, the multiple reference frame (MRF) methodology is used. The results are compared with the experimental results and a good conformity is obtained, which endorses numerical simulation. Furthermore, the turbulence model is used, which is superior to other turbulence models in modeling marine propellers. The investigation focuses on aspects related to the influence of the pressure coefficient and the advance coefficient on hydrodynamic performance and cavitation of the propeller. The results reveal that the pressure coefficient at first decreases and then augments as it moves from the leading edge to trailing edge in the suction surface. Moreover, by increasing the blade radius and its speed, the minimum pressure increases in a way that pressure coefficient reaches its minimum value. Furthermore, volume fraction of the vapor over the blades decreases as the advance coefficient increases. As a result, the possibility of cavitation decreases.

Properties of the ambient noise field recorded at the 150 m isobath during the 2016–2017 Canadian Basin Acoustic Propagation Experiment

The Applied Research Laboratories at the University of Texas at Austin (ARL:UT) deployed two passive acoustic recording systems along the 150 m isobath of the Chukchi Shelf during the 2016–2017 Canadian Basin Acoustic Propagation Experiment (CANAPE). The first system was a single-hydrophone recorder located on the seafloor, while the Persistent Acoustic Observation System (PECOS) contained a horizontal line array of hydrophones along the seabed and a vertical line array spanning a portion of the water column. The systems were deployed and recovered during open-water conditions, but remained in place during the ice-formation, ice-covered, and ice-melt time periods. This talk presents initial findings of the statistical ambient noise levels during the year-long experiment, presents beam-noise levels recorded by PECOS, and qualitatively discusses the natural, biologic, and anthropogenic sounds present in the acoustic recordings. [Work sponsored by ONR.]

Large-Eddy Simulations of a notional submarine in towed and self-propelled configurations

The present study reports results of Large Eddy Simulations (LES) in towed and self-propelled conditions for the DARPA SUBOFF (DSub), a notional submarine geometry, at a Reynolds number, based on the model length, L, and the free-stream velocity, U∞, equal to ReL=1.2×106. An Immersed-Boundary (IB) method was adopted to enforce no-slip boundary conditions on the surface of the body. The approach (LES with IB) was validated by the authors in earlier studies on the towed DSub, as well as on the INSEAN E1619 propeller in open-water conditions. Comparisons between towed and propelled configurations are presented here. Results show that the development of the boundary layer over the cylindrical mid-body is almost unaffected by propeller suction. Instead, the effect over the stern is dramatic, modifying substantially the flow ingested by the same propeller. In the wake the bimodal distribution of the turbulent stresses for the towed case, due to the adverse pressure gradient induced by the tapered geometry of the stern, is replaced in self-propulsion by an axial peak of turbulent kinetic energy, mainly due to instability of the hub vortex.

Foraminiferal assemblages from ice-proximal paleo-settings in the Whales Deep Basin, eastern Ross Sea, Antarctica

Reconstructions of Ross Sea paleoenvironments based on foraminifera are hindered by the dearth of actualistic data, especially from below the Ross Ice Shelf. To fill this gap, we used a recently developed well-resolved deglaciation record from the Whales Deep Basin of the eastern Ross Sea to understand the ecological affinities of different foraminiferal assemblages. During open-water conditions similar to the present, two benthic foraminiferal communities are strongly dominated by agglutinated species. However, in the underlying sediments that represent sub-ice-shelf and grounding-zone proximal settings on the outer continental shelf, we identified five different assemblages of calcareous foraminifera. By Antarctic margin standards, these calcareous assemblages are periodically truly abundant. Along with assemblages dominated by benthic calcareous species that are well known from many Antarctic settings, i.e., Globocassidulina biora, Trifarina earlandi, and Astrononion echolsi, two important assemblages are dominated by a heretofore undescribed pustulose morphotype of G. biora and poorly known spinose morphotype of T. earlandi. Based on our correlations to the deglacial record, these two assemblages live near the grounding line or in environments with especially intense bottom water currents. As grounded and floating ice retreated south to the middle continental shelf, these later sub-ice-shelf and grounding-zone proximal settings were largely devoid of calcareous foraminifera and instead were inhabited by agglutinated taxa. This improved understanding of foraminiferal assemblage distributions from a variety of environments within the eastern Ross Sea may contribute to better use of foraminiferal data to investigate the evolution of environmental changes in grounding-line proximal environments.

Late Holocene ice-wedge polygon dynamics in northeastern Siberian coastal lowlands

ABSTRACT Ice-wedge polygons are common features of northeastern Siberian lowland periglacial tundra landscapes. To deduce the formation and alternation of ice-wedge polygons in the Kolyma Delta and in the Indigirka Lowland, we studied shallow cores, up to 1.3 m deep, from polygon center and rim locations. The formation of well-developed low-center polygons with elevated rims and wet centers is shown by the beginning of peat accumulation, increased organic matter contents, and changes in vegetation cover from Poaceae-, Alnus-, and Betula-dominated pollen spectra to dominating Cyperaceae and Botryoccocus presence, and Carex and Drepanocladus revolvens macro-fossils. Tecamoebae data support such a change from wetland to open-water conditions in polygon centers by changes from dominating eurybiontic and sphagnobiontic to hydrobiontic species assemblages. The peat accumulation indicates low-center polygon formation and started between 2380 ± 30 and 1676 ± 32 years before present (BP) in the Kolyma Delta. We recorded an opposite change from open-water to wetland conditions because of rim degradation and consecutive high-center polygon formation in the Indigirka Lowland between 2144 ± 33 and 1632 ± 32 years BP. The late Holocene records of polygon landscape development reveal changes in local hydrology and soil moisture.