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Weather and sea ice forecasts provided in support of the U.S. Navy's Ice Exercise winter 2020 campaign in the Beaufort Sea noted frequent storms in the absence of the climatological Beaufort High which coincided with anomalous eastward drift of the region's ice cover. To place the 2020 Beaufort‐Chukchi regional atmospheric conditions in historical context, we evaluated winter low sea‐level pressure (SLP) extremes and storm characteristics in the region over the 1948–2020 period. March 2020 SLP in the Beaufort‐Chukchi region was the lowest of the modern reanalysis era (1009.07 hPa) with record counts of passing storms and days with SLP at least two standard deviations below the climatological mean. The Beaufort High collapse in winter 2020 continued a recent pattern of Beaufort High collapses dating back to 2010. Unlike other recent collapses, such as 2017, most of the late‐winter 2020 cyclones originated locally over the western Arctic Ocean. Plain Language Summary: Unusually stormy winter weather occurred in the southern Beaufort Sea during February and March 2020, affecting the U.S. Navy's Ice Exercise (ICEX) operations. Instead of the typical Beaufort High pressure pattern and associated easterly winds, frequent and at times intense storms moved across the Chukchi and Beaufort Seas, ushering westerly winds and eastward drift of sea ice and the ICEX camp. To quantify how unusual these weather conditions were, we evaluated storm activity from 1948 to 2020. March 2020 set a low pressure record for the month, in part because a record‐number of intense storms that moved across the area. This storminess was supported by an unusually strong atmospheric circulation pattern over the Arctic Ocean that aided repetitive storm passage. Since 2010, the late‐winter Beaufort High has been less common amidst more frequent storm activity, and three of the lowest four March mean sea‐level pressure values on record have occurred during the last 4 years. This change in weather conditions has broad implications for the Arctic environment. Key Points: March sea‐level pressure (SLP) in 2020 was the lowest since 1948 over the Beaufort and Chukchi SeasFrequent and intense storms contributed to anomalous eastward sea ice motion in the regionMarch 2020 continued a recent trend of Beaufort High collapse events as three of the four lowest March SLPs have occurred since 2017 [ABSTRACT FROM AUTHOR]

Improving situational awareness and crisis response are key priorities in reducing potential risks associated with sea ice and environmental-related hazards in the Arctic. This research explores the opportunities and challenges associated with leveraging arctic system science research to coproduce sea ice decision support tools. The research is based on information derived from a coastal radar operated as part of university research in Utqiaġvik, Alaska as well as decision context analysis from 12 interviews with marine operators and responders, subsistence users, and service providers. Findings revealed a diversity of information preferences and needs, decision thresholds, capacities, and constraints. A sea ice notification framework is presented, which illustrates how near-real time observations can be integrated into existing trusted notification systems. Key challenges to using Arctic system science research to support decision maker needs include the logistics of operating and maintaining near-real time observations. Innovative partnerships and informal networks may be especially important in overcoming these challenges. [ABSTRACT FROM AUTHOR]

We combine Eulerian ice draft observations from moored ice‐profiling sonars with buoy‐ and satellite‐derived ice drift data to obtain Lagrangian observations of changes in the thickness distribution of sea ice circulating the Beaufort Sea. We examine repeat measurements of ice draft by identifying events where buoys or pseudobuoys made repeat overpasses within 30 km of ice‐profiling sonar‐equipped Beaufort Gyre Exploration Project moorings. Comparison of ice draft distributions from each overpass indicates that summertime melt rates are related to drift track, with more melt occurring in the southern Beaufort Sea than to the north. Additionally, we find that ice surviving summer in the Beaufort Sea since 2007 is similar in thickness to surrounding first‐year sea ice by the end of the following winter. These findings are supported by continuous ice thickness data from ice mass balance buoys. By examining "plumes" of pseudobuoys originating at each mooring location, we identify anomalous northward transport of ice in the southern Beaufort Sea in 2007 that likely contributed to the record‐breaking reduction in sea ice extent that year. We also find that repeat overpasses have been much rarer since 2007, due to reduced summertime sea ice extent in the Beaufort Gyre and possible changes in ice drift patterns. These changes contribute to diminished replenishment of multiyear sea ice volume in the Arctic. Plain Language Summary: Using ice motion data from buoys and satellites, we track sea ice as it circulates in the Beaufort Gyre and measure changes in its thickness as it passes over moored upward looking sonars. Our results show that ice drifting through the southern Beaufort Sea in summer experiences significant thinning and that multiyear ice surviving the summer does not grow much thicker than first‐year ice even after multiple winters. We also find that the northward retreat of the summertime ice edge in Beaufort Sea is leading to a reduced likelihood of ice recirculating and growing older and thicker in the Beaufort Gyre. Together, these changes make any recovery of the Arctic ice pack increasingly unlikely. Key Points: Sea ice in the Beaufort Gyre is tracked as it drifts over upward looking sonars to derive Lagrangian changes in its thickness distributionSea ice traversing the Beaufort Sea south of ~75°N experiences significantly greater melt since 2007 than ice to the northBy the end of winter, perennial ice surviving summer in the Beaufort Gyre is similar in thickness to first‐year ice grown in just one season [ABSTRACT FROM AUTHOR]

Abstract: Through analysis of over 2500 synthetic aperture radar (SAR) scenes spanning the period 1996–2008, we have compiled the most comprehensive dataset to date on landfast sea ice extent and its annual cycle in the Chukchi and Beaufort Seas. Our results show that landfast ice in the central and western Beaufort Sea forms earlier, breaks up later, occupies deeper water and extends further from shore than that in the Chukchi Sea. The differences in the timing of the annual landfast ice cycle are largely due to regional contrasts in the southward advance of pack ice in early winter and the onset of spring thaw. On the other hand, we suggest that the differences in landfast ice extent between the two seas are related to the number and distribution of recurring grounded ice features. These grounded features appear as “nodes” where the seaward landfast ice edge (SLIE) persistently recurs in multiple years. In the Beaufort Sea there are several such nodes that occur in water depths around 20m, giving rise to the similarity between the average SLIE location and the 20m isobath. We attribute the narrower landfast ice in the Chukchi Sea and lack of a consistent relationship with bathymetry to the sparsity of nodes in the Chukchi Sea. In comparing our results with data from the period 1973–76, we find that landfast ice extent in the Beaufort Sea has not changed significantly in the last four decades. However, in the Chukchi Sea our results show the landfast ice width has decreased by a coast-wide average of 13km over this period. We again attribute this difference between the two seas to the distribution of recurring grounded ice features. Over the 12 annual cycles in the study period, we identify trends indicating that landfast ice is forming later and disappearing earlier by approximately one week per decade. Although these trends are not statistically significant, they are in agreement with an overall shortening of the landfast ice season by as much as two months over the past three decades, revealed by a comparison with earlier findings for the period 1973–77. [Copyright &y& Elsevier]

Abstract: In recent years methods have been developed to extract the seaward landfast ice edge from series of remote sensing images, with most of them relying on incoherent change detection in optical, infrared, or radar amplitude imagery. While such approaches provide valuable results, some still lack the required level of robustness and all lack the ability to fully automate the detection and mapping of landfast ice over large areas and long time spans. This paper introduces an alternative approach to mapping landfast ice extent that is based on coherent processing of interferometric L-band Synthetic Aperture Radar (SAR) data. The approach is based on a combined interpretation of interferometric phase pattern and interferometric coherence images to extract the extent and stability of landfast ice. Due to the low complexity of the base imagery used for landfast ice extraction, significant improvements in automation and reduction of required manual interactions by operators can be achieved. A performance analysis shows that L-band interferometric SAR (InSAR) data enable the mapping of landfast ice with high robustness and accuracy for a wide range of environmental conditions. [Copyright &y& Elsevier]

Bottomfast sea ice is an integral part of many near-coastal Arctic ecosystems with implications for subsea permafrost, coastal stability and morphology. Bottomfast sea ice is also of great relevance to over-ice travel by coastal communities, industrial ice roads, and marine habitats. There are currently large uncertainties around where and how much bottomfast ice is present in the Arctic due to the lack of effective approaches for detecting bottomfast sea ice on large spatial scales. Here, we suggest a robust method capable of detecting bottomfast sea ice using spaceborne synthetic aperture radar interferometry. This approach is used to discriminate between slowly deforming floating ice and completely stationary bottomfast ice based on the interferometric phase. We validate the approach over freshwater ice in the Mackenzie Delta, Canada, and over sea ice in the Colville Delta and Elson Lagoon, Alaska. For these areas, bottomfast ice, as interpreted from the interferometric phase, shows high correlation with local bathymetry and in-situ ice auger and ground penetrating radar measurements. The technique is further used to track the seasonal evolution of bottomfast ice in the Kasegaluk Lagoon, Alaska, by identifying freeze-up progression and areas of liquid water throughout winter. [ABSTRACT FROM AUTHOR]

Recent Arctic warming has led to reduced sea-ice thickness and a more dynamic landfast ice cover with potential widespread consequences for ice users. Here, we develop an approach to assess the small-scale deformation of landfast ice critical to on-ice operations using synthetic aperture radar interferometry (InSAR). InSAR has previously proven successful in determining long-term qualitative climatology of ice deformation around on-ice operations, but is now used to explore its potential for providing quantitative guidance for ice road planning, construction, and maintenance. A validation effort using X-band SAR and high-precision GPS data over Elson Lagoon, Alaska, confirms the ability of InSAR to accurately estimate 3-dimensional sea ice strain values accumulated between SAR image acquisitions, using an inverse model. The inverse model was further applied to L-band InSAR data over the Northstar Island ice road near Prudhoe Bay, Alaska. Assuming an elasto-brittle rheology, the derived strain values yielded a spatial distribution of internal stress consistent with preexisting ice defects and morphology. In several localized regions of the study area, stress values exceeded expected yield stress. Resulting relative fracture intensity potential was shown to conform with local knowledge based on road inspections by engineers, and may be used to guide ice road planning, construction and maintenance efforts. The results presented here demonstrate that InSAR is an accurate tool for estimating landfast ice deformation and stability in support of ice use. The findings may also provide substantial new insights into the mechanics of landfast ice. [ABSTRACT FROM AUTHOR]

Rapid environmental change and increases in use of shorefast ice by industry and coastal communities highlight the need for an approach to accurately assess landfast sea-ice stability on seasonal timescales. While stability can sometimes be inferred from field measurements, current methods are lacking robustness and the ability to be automated and applied over large areas and long time scales to ensure safety and document change in the context of transportation, indigenous ice uses and industrial development. This paper introduces an inverse model capable of reconstructing three-dimensional deformation fields from one-dimensional interferometric L-band Synthetic Aperture Radar (SAR) phase patterns. We apply this method at three landfast ice locations on the Alaska Beaufort Sea coast near Barrow and Prudhoe Bay. We find the small-scale displacements estimated from the model consistent with regional patterns of ice motion. Our study suggests that interferometry can provide planning and decision-support information for ice road development and structures operating within ice. Moreover, InSAR can potentially increase our understanding of sea ice on a fundamental level in terms of large-scale stability and long-term changes in ice dynamics. [ABSTRACT FROM AUTHOR]