Frazil Ice Growth Research Articles

Assessment of the Pan-Arctic Accelerated Rate of Sea Ice Decline in CMIP6 Historical Simulations

Abstract Arctic sea ice loss in response to a warming climate is assessed in 42 models participating in phase 6 of the Coupled Model Intercomparison Project (CMIP6). Sea ice observations show a significant acceleration in the rate of decline commencing near the turn of the twenty-first century. It is our assertion that state-of-the-art climate models should qualitatively reflect this accelerated trend within the limitations of internal variability and observational uncertainty. Our analysis shows that individual CMIP6 simulations of sea ice depict a wide range of model spread on biases and anomaly trends both across models and among their ensemble members. While the CMIP6 multimodel mean captures the observed sea ice area (SIA) decline relatively well, an individual model’s ability to represent the acceleration in sea ice decline remains a challenge. Seventeen (40%) out of 42 CMIP6 models and 37 (13%) out of the total 286 ensemble members reasonably capture the observed trends and acceleration in SIA decline. In addition, a larger ensemble size appears to increase the odds for a model to include at least one ensemble member skillfully representing the accelerated SIA trends. Simulations of sea ice volume (SIV) show much larger spread and uncertainty than SIA; however, due to limited availability of sea ice thickness data, these are not as well constrained by observations. Finally, we find that models with more ocean heat transport simulate larger sea ice declines, which suggests an emergent constraint in CMIP6 ensembles. This relationship points to the need for better understanding and modeling of ice–ocean interactions, especially with respect to frazil ice growth.

Wave-influenced formation of new ice: Model building and a test case

A parameterization of new ice formation in a wave field has been developed. Detailed processes of new sea ice growth with multiple ice types (nilas, grease, and pancake ice) and associated wave attenuation by different sea ice types are presented and implemented into a coupled ROMS and SWAN model. Sea ice formation includes growth and transformation of frazil, grease, pancake, nilas and solid ice. Ice types are determined by thermal condition and the wave fields. Simultaneously, the attenuation of wave energy through the ice cover is dependent on ice types. The two processes are coupled by COAWST. The resulting coupled model is applied to the Bohai Sea. When compared with in-situ data from oil platforms, the model performed well in distinguishing solid ice, pancake and nilas. When compared with previous ice models without the consideration of new ice types, the appearance of solid ice is delayed, the total ice area and ice volume are increased, solid ice thickness is increased while the type-averaged thickness is reduced and heat flux from the ocean to air is increased during the freezing phase. By considering the new ice formation, wave attenuation in the test case is enhanced.

Disentangling the Coupled Atmosphere‐Ocean‐Ice Interactions Driving Arctic Sea Ice Response to CO2 Increases

AbstractA novel decomposition of the ocean heat energy that contributes to sea ice melt and growth (ocean‐ice and frazil heat) into components that are driven by surface heat flux and ocean circulation changes is used to isolate the evolving roles of the atmosphere and ocean in the Arctic sea ice loss from CO2 increases. A sea ice volume budget analysis is used to separate the impacts of the anomalous frazil/ocean‐ice heat from those of atmosphere‐ice heat on the evolving Arctic sea ice volume. The role of atmosphere‐ocean coupling in augmenting or curtailing the atmosphere‐ and ocean‐driven sea ice losses is further isolated by comparing the ice volume budget and the anomalous frazil/ocean‐ice heat components in partially and fully coupled experiments. Atmosphere‐ice heat fluxes drive most of Arctic sea ice loss in the first decade following CO2 increase by increasing the sea ice top face melt in summer, while ocean circulation changes drive the loss over the longer term through the anomalous increase of heat transport into the Arctic, which drive decreases in frazil ice growth and sea ice extent in winter. Atmosphere‐ocean coupling in the subpolar Atlantic further supports a negative feedback that attenuates the ocean‐driven sea ice losses over time; by accelerating the weakening of the Atlantic meridional overturning circulation, it causes a large cooling of the subpolar Atlantic and attenuation of the anomalous heat transport into the Arctic in winter, allowing for a seasonal Arctic sea ice in the fully coupled experiment, while the Arctic completely becomes ice free in the partially coupled experiment.

Frazil ice growth and production during katabatic wind events in the Ross Sea, Antarctica

Abstract. Katabatic winds in coastal polynyas expose the ocean to extreme heat loss, causing intense sea ice production and dense water formation around Antarctica throughout autumn and winter. The advancing sea ice pack, combined with high winds and low temperatures, has limited surface ocean observations of polynyas in winter, thereby impeding new insights into the evolution of these ice factories through the dark austral months. Here, we describe oceanic observations during multiple katabatic wind events during May 2017 in the Terra Nova Bay and Ross Sea polynyas. Wind speeds regularly exceeded 20 m s−1, air temperatures were below −25 ∘C, and the oceanic mixed layer extended to 600 m. During these events, conductivity–temperature–depth (CTD) profiles revealed bulges of warm, salty water directly beneath the ocean surface and extending downwards tens of meters. These profiles reflect latent heat and salt release during unconsolidated frazil ice production, driven by atmospheric heat loss, a process that has rarely if ever been observed outside the laboratory. A simple salt budget suggests these anomalies reflect in situ frazil ice concentration that ranges from 13 to 266×10-3 kg m−3. Contemporaneous estimates of vertical mixing reveal rapid convection in these unstable density profiles and mixing lifetimes from 7 to 12 min. The individual estimates of ice production from the salt budget reveal the intensity of short-term ice production, up to 110 cm d−1 during the windiest events, and a seasonal average of 29 cm d−1. We further found that frazil ice production rates covary with wind speed and with location along the upstream–downstream length of the polynya. These measurements reveal that it is possible to indirectly observe and estimate the process of unconsolidated ice production in polynyas by measuring upper-ocean water column profiles. These vigorous ice production rates suggest frazil ice may be an important component in total polynya ice production.

Frazil-ice growth rate and dynamics in mixed layers and sub-ice-shelf plumes

Abstract. The growth of frazil or granular ice is an important mode of ice formation in the cryosphere. Recent advances have improved our understanding of the microphysical processes that control the rate of ice-crystal growth when water is cooled beneath its freezing temperature. These advances suggest that crystals grow much faster than previously thought. In this paper, we consider models of a population of ice crystals with different sizes to provide insight into the treatment of frazil ice in large-scale models. We consider the role of crystal growth alongside the other physical processes that determine the dynamics of frazil ice. We apply our model to a simple mixed layer (such as at the surface of the ocean) and to a buoyant plume under a floating ice shelf. We provide numerical calculations and scaling arguments to predict the occurrence of frazil-ice explosions, which we show are controlled by crystal growth, nucleation, and gravitational removal. Faster crystal growth, higher secondary nucleation, and slower gravitational removal make frazil-ice explosions more likely. We identify steady-state crystal size distributions, which are largely insensitive to crystal growth rate but are affected by the relative importance of secondary nucleation to gravitational removal. Finally, we show that the fate of plumes underneath ice shelves is dramatically affected by frazil-ice dynamics. Differences in the parameterization of crystal growth and nucleation give rise to radically different predictions of basal accretion and plume dynamics, and can even impact whether a plume reaches the end of the ice shelf or intrudes at depth.

Vertical Modification on Depth-Integrated Ice Shelf Water Plume Modeling Based on an Equilibrium Vertical Profile of Suspended Frazil Ice Concentration

AbstractThe ice shelf water (ISW) plume is a prevalent phenomenon at the base of an ice shelf or sea ice adjacent to the ice shelf front. Such plumes may become supercooled and deposit marine ice when they rise. In the existing frazil ice–laden ISW plume models, it is generally assumed that supercooling and frazil ice growth can be adequately treated by using depth-averaged freezing temperature and vertically uniform frazil ice concentration within a plume. In reality, however, the temperature deficit and frazil ice concentration both increase toward the top of the plume. Hence, frazil crystals typically experience a greater deficit than that suggested by the plume’s temperature subtracted from its depth-averaged freezing point. In this study, the authors considered the combined nonlinear effects of vertical structures of frazil ice concentration and thermal forcing within an ISW plume by introducing equilibrium vertical profiles of frazil ice concentration into a horizontal two-dimensional depth-integrated ISW plume model. A series of idealized numerical experiments and an observation-based simulation beneath the western side of Ronne Ice Shelf have been conducted by using the vertically modified and original depth-integrated ISW plume models. It was found that the supercooled area, supercooling level, and suspended frazil ice and marine ice productivities are all substantially underestimated by the original models. Moreover, the differences are sensitive to the selected frazil ice size configuration. These results suggest that the vertical modification introduced in this study can significantly improve simulated marine ice distribution and its corresponding production, in comparison with those estimated by previous depth-integrated models.

Modeling frazil ice growth in the St. Lawrence River

The paper presents a complete energy balance model of suspended frazil ice formation in the tidal water column of the St. Lawrence River. The model estimates of suspended frazil ice concentration are compared to in situ observations of an analogue of suspended frazil ice crystals, with good results. A time series of observed acoustic backscattering from suspended frazil serves as the analogue of the suspended frazil concentration. The model of frazil ice growth is used to estimate the rate of increase in mass of the suspended frazil ice by balancing the net rate of energy exchange with the atmosphere with the observed changes in water temperature and in anchor ice thickness. The positive results are achieved despite a number of difficulties with analysis. These difficulties include the bias resulting from the inability of the sonar to detect across the complete size range of suspended ice, the unknown impacts of advection, the unknown impact of anchor ice build-up on temperature and sonar readings, and the lack of knowledge regarding the accuracy of sonar estimation of anchor ice thickness. These results highlight the promise of models, suitably applied, and sonar to quantitatively estimate suspended frazil ice concentration.

Solidification of a disk-shaped crystal from a weakly supercooled binary melt.

The physics of ice crystal growth from the liquid phase, especially in the presence of salt, has received much less attention than the growth of snow crystals from the vapor phase. The growth of so-called frazil ice by solidification of a supercooled aqueous salt solution is consistent with crystal growth in the basal plane being limited by the diffusive removal of the latent heat of solidification from the solid-liquid interface, while being limited by attachment kinetics in the perpendicular direction. This leads to the formation of approximately disk-shaped crystals with a low aspect ratio of thickness compared to radius, because radial growth is much faster than axial growth. We calculate numerically how fast disk-shaped crystals grow in both pure and binary melts, accounting for the comparatively slow axial growth, the effect of dissolved solute in the fluid phase, and the difference in thermal properties between solid and fluid phases. We identify the main physical mechanisms that control crystal growth and show that the diffusive removal of both the latent heat released and the salt rejected at the growing interface are significant. Our calculations demonstrate that certain previous parametrizations, based on scaling arguments, substantially underestimate crystal growth rates by a factor of order 10-100 for low aspect ratio disks, and we provide a parametrization for use in models of ice crystal growth in environmental settings.

On the Conditional Frazil Ice Instability in Seawater

AbstractIt has been suggested that the presence of frazil ice can lead to a conditional instability in seawater. Any frazil forming in the water column reduces the bulk density of a parcel of frazil–seawater mixture, causing it to rise. As a result of the pressure decrease in the freezing point, this causes more frazil to form, causing the parcel to accelerate, and so on. This study uses linear stability analysis and a nonhydrostatic ocean model to study this instability. The authors find that frazil ice growth caused by the rising of supercooled water is indeed able to generate a buoyancy-driven instability. Even in a gravitationally stable water column, the frazil ice mechanism can still generate convection. The instability does not operate in the presence of strong density stratification, high thermal driving (warm water), a small initial perturbation, high background mixing, or the prevalence of large frazil ice crystals. In an unstable water column, the instability is not necessarily expressed in frazil ice at all times; an initial frazil perturbation may melt and refreeze. Given a large enough initial perturbation, this instability can allow significant ice growth. A model shows frazil ice growth in an Ice Shelf Water plume several kilometers from an ice shelf, under similar conditions to observations of frazil ice growth under sea ice. The presence of this instability could be a factor affecting the growth of sea ice near ice shelves, with implications for Antarctic Bottom Water formation.

Experimental Study on Characteristic of Growth of Frazil and Pancake Ice

We conducted laboratory experiments to monitor frazil/pancake ice growth from open water condition in an indoor wave tank cooled at -8 degree. Salt water with concentration of 35psu was used similar to ocean conditions. In the growth of frazil ice, the deposition thickness and the rise velocity were measured and in that of pancake ice, the size was recorded at 2 hours interval during about 16 hours, respectively. As a result, when whole sea water in the tank supercooled, the frazil ice is actively generated not only on surface but also in the deeper water. The maximum deposition thickness becomes about 6 mm per an hour. Finally, the sizes of pancake could be estimated by probability density function based on logarithmic normal distribution.

Sonar detection and measurement of ice in a freezing river II: Observations and results on frazil ice

Results from 2004–2008 BC Hydro SWIPS (Shallow Water Ice Profiling Sonar) monitoring programs on the Peace River are presented and analyzed with respect to their content of information on the properties and behaviour of frazil ice suspended in water column. Strong distinctions were made in analyses applied to data collected, respectively, prior to and following local stabilization of the seasonal ice cover. This choice is shown to reflect both the behaviour and origins of the frazil ice present in these two intervals. Pre-freeze-up frazil tends to coat submerged surfaces, grows rapidly while in suspension and is only rarely and episodically present. It shows time dependences quite different from those associated with frazil detected prior to freeze-up. Frazil under a stationary ice cover is ubiquitous, does not adhere to other materials and appears to closely associated with the ice cover undersurface. The return intensity profiles observed in pre-freeze-up frazil events increased roughly linearly with height in the water column. Profile comparisons with earlier simulation results allowed inferences on particle size distributions and their controlling processes. The bulk of data analysis efforts was devoted to clarifying the time dependences of the more abundant post-stabilization SWIPS intensity data and its underlying connections to changes in the major river, atmosphere and ice cover environmental parameters. The obtained results showed unlagged or weakly negatively-lagged, positive correlations between such intensities and both river water levels and air temperatures (or solar radiation input) on, at least, diurnal and shorter time scales. The water level parameter was the stronger of these two influences and was believed to be representative of a physical link to river flow speed. Lower frequency connections to the physical state of the ice cover were also apparent. Interpretations of these results were offered in terms of a local equilibrium between the suspended frazil population and a dynamic slush layer at the bottom of the ice cover. Initial steps were taken toward developing and testing analysis tools potentially capable of supporting combined analysis and modelling of this equilibrium. A simple interpretative approach was applied to data acquired at a single acoustic frequency based upon combined use of a Rouse Law-based Inverted sediment model of uniformly-sized spherical frazil particles and volume backscattering coefficients measured in post-freeze-up intervals. Results suggested consistency with the basic form of return intensity profiles at most but not all times. For suitable measurement periods, the approach yielded reasonable estimates of the major particle size and concentration parameters. The deficiencies of this approach are discussed and compared with expectations and results from recently successful simultaneous measurements at two acoustic frequencies. Priorities are identified for validation, and refinement of single and multifrequency approaches along with integrated study of the lower ice cover as part of a broader program to understand frazil ice growth in freezing rivers.

Simulating pancake and frazil ice growth in the Weddell Sea: A process model from freezing to consolidation

Processes controlling the formation and transformation of frazil to pancake ice are examined using data from an array of drifting buoys deployed at the advancing ice edge in the Weddell Sea. A simple thermodynamic model is coupled to the buoy dynamics and to an ice redistribution model to determine the influence of deformation, thermodynamics, and mechanical scavenging, incorporating frazil crystals from the surrounding slick into the pancakes, on the partitioning of ice volume between frazil and pancakes. Ice production was examined from the time the buoys were deployed until the frazil/pancake cover consolidated into the more familiar pack ice. The model reproduced the expected ice cover thickness at consolidation (60 cm). Rafting was the dominant contribution to thickening in the region owing to large‐scale compression of the initial area by northerly winds from passing low‐pressure weather systems, which are rather typical in the region. High‐resolution positional forcing from the buoys (20‐min intervals) doubled the contribution of mechanical scavenging to final pancake thickness compared to the coarser (2‐h) result, owing to the larger path length that the pancakes traverse through the frazil slick, and produced a significantly larger volume of ice in the pancake phase. The ice cover generated at consolidation was approximately twice as thick as would have formed by the more familiar congelation ice growth under the same forcing, reinforcing the importance of correctly parameterizing the early stages of ice formation in the Antarctic. The study highlighted uncertainties in the effect of the frazil/pancake cover on ocean‐atmosphere heat exchange, both in terms of the area contributing to ice production and the effect on turbulent exchange coefficients. Further work placing the empirical parameters into a more constrained physical framework and introducing wave properties is suggested.

Observations of hydrography and downflow of brine‐enriched shelf water in the Storfjorden polynya, Svalbard

Observations of hydrography and currents in the active Storfjorden polynya during fieldwork in April 2004 and 2006 are presented. The polynya adds salt from its efficient ice production, usually increasing the density ∼0.15 kg m−3. Downflow of dense water from the coastal polynya to the deeper basin enclosed by the Storfjorden sill was captured in both years. April 2006 had a period of strong heat loss and intense frazil ice growth in the polynya. This created downflow of brine‐enriched shelf water (BSW) with a maximum salinity of 35.25, i.e., an increased density ∼0.4 kg m−3 above that of the source water. In April 2004, the salinity remained lower than BSW (S > 34.8), reflecting the fresh source water in fall 2003 due to the heavy ice conditions in the western Barents Sea that year. A portion (0.05 Sv) of such source water probably enters Storfjorden through Freemansundet where the mean current transports less saline and warmer water from the northwestern Barents Sea. Freemansundet has additionally a strong tidal current peaking at 53 cm s−1, dominated by the M2 component. The tidal wave propagates through the narrow sound producing shallow water components and a locally well‐mixed water column. The estimated ice production in winter 2004, twice as large as that of winter 2006, could not overcome this less saline well‐mixed source water. BSW downflow within Storfjorden was both observed and modeled to occur in areas with steep bathymetry. Our observations show that high‐resolution hydrographical data, spacing less than 0.5 km, are necessary to resolve such downflow. Consistent with the observed polynya water salinity, current data at the sill showed weaker overflow in 2004 than in 2006. Overflow of BSW was observed on the eastern part of the Storfjorden sill in April 2006, indicating that overflow occurs across the entire sill width during the freezing period. Current, temperature, and salinity data from the overflow indicate a time lag of 12–18 days between the BSW production and the sill. This downflow–overflow link is confirmed by a numerical experiment and analytical scaling, making results applicable to other polynyas.

On the Nusselt number for frazil ice growth—a correction to ”Frazil evolution in channels“ by Lars Hammar and Hung-Tao Shen

The growth (melt) rate of frazil ice is governed by heat transfer away from (towards) the ice crystal, which can be represented by the Nusselt number. We discuss choices for the Nusselt number and turbulent length scale appropriate for frazil ice and note an inaccuracy in the study ”Frazil evolution in channels“ by Lars Hammar and Hung-Tao Shen, which has also led to potentially significant errors in several other papers. We correct this error and suggest an appropriate strategy for determining the Nusselt number applicable to frazil ice growth and melting.

A quantitative framework for interpretation of basal ice facies formed by ice accretion over subglacial sediment

We have constructed a numerical model of basal ice formation for glacier ice in contact with subglacial sediment. The model predicts four different ice facies whose formation is controlled by availability of subglacial water to satisfy the basal freeze‐on rate. Clean (or clotted) facies may result from congelation (or frazil) ice growth occurring when (supercooled) meltwater separates ice base from substrate or if a groundwater source can supply water to the ice base at a velocity equal to the freezing rate. Laminated facies develops when the supply of subglacial water is sufficiently constrained for cryostatic suction to raise the subglacial effective stress above a threshold for intrusion of ice into sediment by regelation. Debris laminas (∼1 mm) are entrained by short, periodic regelation events (of a few hours) separated by longer periods (days to months) of congelation. Further meltwater limitation produces a massive dirty ice facies due to stacking of debris laminas. The model predicts growth of solid dirty ice facies when the bed is meltwater‐depleted with fast freezing (5 mm yr−1) causing enhanced erosion (30 mm yr−1). We find that basal ice facies and sediment entrainment are controlled mainly by the ratio of freezing rate to water supply rate. The predicted ice facies compare favorably with borehole camera imagery of the basal ice layer in Kamb Ice Stream, West Antarctica. Facies variability in this layer suggests complex hydrologic history for the West Antarctic Ice Sheet with significant changes occurring over a period of several thousand years.

Simulation of the supercooling process and frazil evolution in turbulent flows

A model to simulate the supercooling process and frazil ice evolution in a counter-rotating flume is developed based on a series of laboratory experiments. The characteristics of the supercooling process were found to be related to air temperature and flow turbulence. Frazil ice growth was observed to follow a log-normal distribution model. The model avoids the need to simulate seeding, secondary nucleation, flocculation–breakup, and gravitational removal. Only the overall heat balance is considered during the entire process. The simulations show good agreements with experimental time–temperature curves and frazil evolution.Key words: supercooling, frazil ice, size distribution, concentration, turbulence, simulation.

Thickness distribution, texture and stratigraphy, and a simple probabilistic model for dynamical thickening of sea ice in the southern Sea of Okhotsk

Sea ice thickness data and sea ice samples were analyzed to examine the characteristics of the ice thickness distribution and ice texture, and to understand ice growth processes in the southern Sea of Okhotsk. Ice thickness data and samples were obtained aboard the icebreaker Soya in early February, the ice growth season. Ice thickness data, which were obtained with a video monitoring system installed on the side deck of the ship each winter from 1991 to 2000 except 1995, show that the average thickness ranges from 19 ± 7 to 55 ± 23 cm and that it matches the characteristics of a Poisson distribution. Ice structure analysis reveals that granular texture occupies about three quarters of the total ice thickness and that the ice exhibits a layered structure with unit thickness averaging 5 to 10 cm. Stratigraphy and stable isotopic composition of the ice indicate that snow ice accounts for 10% and frazil ice accounts for 64% of the total ice thickness. This suggests that dynamic ice thickening processes such as frazil ice growth and piling up are more significant than congelation growth. On the basis of these characteristics, which resemble more those of Antarctic than Arctic sea ice, we propose a conceptual model for the ice thickening process in this region. It is shown that this model can explain the shape of the ice thickness distribution well, and is analogous with the concept of the “pancake cycle” and multiple rafting of Antarctic sea ice growth and thickening.

Pancake ice formation in the Weddell Sea

The ice formation resulting from two low temperature events at the Weddell Sea ice edge during April 2000 is presented. Pancake and frazil ice were sampled at seven stations at varying distances from the ice edge. The ice cover was further characterized from above, using helicopter aerial photography, and from below, using a remotely operated vehicle. Previously undescribed two‐layer pancake types were observed and classified. A novel pancake growth mechanism is introduced to account for these, involving the washing of frazil ice over the pancake top surface and its subsequent freezing. The process was directly observed in ice tank experiments. Layer thicknesses seen in the field were compared to the ice growth that would occur both under calm conditions and from free‐surface frazil ice growth. Classical, bottom accretion, pancake growth was found to proceed at a rate similar to that of thin congelation ice. Top‐layer growth was more rapid, at approximately double the congelation rate. Overall ice volume production was similar to congelation ice for the thin pancakes considered (∼20 cm), though subsequent thickening was expected to be faster as the rapid top‐layer process continued and the equivalent congelation growth slowed. It is suggested that parameterization of this new process is important for models that aim to simulate the rapid advance and thickening of wave‐influenced ice covers.

Laboratory tests of a time-domain reflectometry system for frazil ice detection

A prototype, electromagnetic-based frazil ice detection system (patent pending) has been developed and tested under simulated frazil ice accretion conditions in an environmentally controlled flume. The system employs a time-domain reflectometer (TDR) and specially designed transmission line sensor to monitor the accretion of frazil ice by measuring the propagation time along the sensor when it is submerged. Changes in the round-trip travel time of the TDR pulse result from a decrease in the localized bulk dielectric constant as frazil ice accretes and displaces water around the sensor. Two frazil detection sensor configurations were tested, a parallel transmission line probe and a semicylindrical mesh coaxial probe. During 2 h long experiments, the TDR clearly indicated a decreasing probe propagation time as frazil ice continued to accrete. This is indicative of the decreasing bulk dielectric constant of the frazil ice and water mix. Continuous real-time data from the TDR were recorded. From these data, an estimate of volumetric ice fraction was calculated using a simple linear dielectric mixing equation. Volumetric ice fractions estimates for both probe configurations were calculated to increase from approximately 0.02 to 0.18 during the test. The system shows promise for detection and measurement of frazil ice growth and accretion in freshwater bodies.Key words: frazil ice, trash rack, water intake, icing detection, time-domain reflectometry, TDR.

Tracking of Ice Edges and Ice Floes by Wavelet Analysis of SAR Images

This paper demonstrates the use of wavelet transforms in the tracking of sequential ice features in the ERS-1 synthetic aperture radar (SAR) imagery, especially in situations where feature correlation techniques fail to yield reasonable results. Examples include the evolution of the St. Lawrence polynya and summer sea ice change in the Beaufort Sea. For the polynya, the evolution of the region of young ice growth surrounding a polynya can be easily tracked by wavelet analysis due to the large backscatter difference between the young and old ice. Also within the polynya, a 2D fast Fourier transform (FFT) is used to identify the extent of the Langmuir circulation region, which is coincident with the wave-agitated frazil ice growth region, where the sea ice experiences its fastest growth. Therefore, the combination of wavelet and FFT analysis of SAR images provides for the large-scale monitoring of different polynya features. For summer ice, previous work shows that this is the most difficult period for ice trackers due to the lack of features on the sea ice cover. The multiscale wavelet analysis shows that this method delineates the detailed floe shapes during this period, so that between consecutive images, the floe translation and rotation can be estimated.