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Study Title Landfast Ice Climatology within the Arctic OCS

Report Title Landfast Ice Climatology within the Arctic OCS

Report Number(s) (OCS Study) BOEM 2024-034

Completion Date of Report August 2024

Number of Pages 121

Award Number(s) M19AC00021

Sponsoring OCS Region or 

Office Alaska OCS Region

Applicable Planning Area(s) Beaufort Sea, Chukchi Sea, Hope Basin

Fiscal Year(s) of Study 

Funding FY 2019–2025 

Costs by Fiscal Year FY2019: $481,376; FY2020: $428,985; FY2021; 449,042; FY2022: 0; 

FY2023 $339,890

Cumulative Project Cost $1,699,293.00

Project Manager(s) Andrew R. Mahoney

Affiliation of Project 

Manager(s) University of Alaska Fairbanks, Geophysical Institute

Address of Project Manager(s) 2156 Koyukuk Dr.

Fairbanks, AK, 99775-7320

Principal Investigator(s) Andrew R. Mahoney, Peter Bieniek, Seth Danielson, Andrew H. Einhorn, 

Kate S. Hedstrom, Joshua M. Jones, and Thilo Klenz

Keywords Sea ice, landfast ice, Beaufort Sea, Chukchi Sea

ABSTRACT: In this study, we have created a 27-year climatology of landfast ice extent in the Arctic Outer 

Continental Shelf (OCS), which we refer to as the EM2024 dataset. This record shows there are 

significant trends toward a shorter duration and reduced extent of landfast ice across the region. In-situ 

field observations of landfast ice that suggests landfast ice may be less susceptible to basal melting in 

spring as long as it remains landfast. We also investigated the specific role that storms may play in 

destabilizing landfast ice and found that a significant number of breakout events are associated with the 

occurrence of storms in the southern Bering Sea, which is consistent with previous suggestions that 

storm-triggered shelf waves may destabilize landfast ice. Lastly, we simulated 25 years of past landfast 

ice extent within the Arctic OCS by implementing a basal shear stress parameterization in a modular 

ocean model 6-sea ice simulator 2 (MOM6-SIS2) coupled ice-ocean model. In doing so, we demonstrate 

that the Alaska Arctic OCS is an ideal test ground for refining model parameter choices and the EM2024 

dataset represents a valuable benchmark for quantifying model performance.

BACKGROUND: This project represents the extension of the landfast ice component of two prior projects 

supported by the Bureau of Ocean Energy Management (BOEM), or its predecessor the Minerals 

Management Service (MMS): MMS OCS Study 2005-068 and BOEM OCS Study 2012-067. The latter 

of these prior studies produced landfast climatology data covering the Arctic OCS for the years 1996–

2008. In this study we adopt the same study region (Figure 1) and extend the timeline to July 2023. This 

project also goes beyond the scope of the preceding work by including a program of field observations, a 

reanalysis-based study of storm impacts, and a modeling component designed to improve Arctic-wide 

simulation of landfast ice. The modeling component also builds on prior BOEM and MMS projects, 

including most recently OCS Study BOEM 2018-018. 
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OBJECTIVES: This study completed 5 of the following 7 objectives:

Objective 1: Develop an updated and readily updateable landfast ice database for the BOEM Alaska OCS 

Region using geospatial information contained in electronic ice charts produced by the National 

Weather Service (NWS) Alaska Sea Ice Program (ASIP) data sets. 

Objective 2: Collect in-situ data documenting the mass balance (growth and melt) of landfast ice in the 

study region, including measurements of ice thickness and snow depth and oceanographic conditions 

of the water below.

Objective 3: Examine the mechanisms by which storms and atmospheric phenomena impact the extent 

and stability of landfast ice

Objective 4: Develop an improved parameterization scheme for modeling landfast ice in the nearshore 

Beaufort Sea that will allow creation of a realistic, high-resolution simulation data set of landfast ice 

growth and decay in the nearshore Beaufort coast over the last 10 years. 

Objective 5: Utilize an existing Regional Climate Model to predict how landfast ice extent may change 

along the Beaufort, Chukchi, and Bering shelf areas over the next thirty years. 

Objective 6: Work with existing observation networks to document significant changes or unusual events 

affecting landfast ice near coastal communities and the impacts of these changes on coastal erosion, 

storm surges, subsistence activities.

Objective 7: Establish a Scientific Review Board (SRB) that has the proper expertise to provide guidance 

and oversight on the progress and implementation of the study’s objectives. 

Objectives 5 and 6 were omitted at the recommendation of the SRB. In the case of objective 5, this 

recommendation was made due to inherent challenges of forcing an ice-ocean model with long-term 

atmospheric forecast data without imposing the prevailing ice conditions in the forecast. Objective 6 was 

omitted following difficulties in establishing connections with community based observing networks 

during the COVID-19 pandemic.

METHODS:

Extended climatology of landfast ice: The EM2024 dataset relied on the delineation of landfast ice in 

ice charts compiled by the U.S. National Ice Center (NIC) and the National Weather Service (NWS) 

Alaska Sea Ice Program (ASIP). These were rasterized to the same grid and analyzed using the same 

techniques originally developed for MMS OCS Study 2005-068. We also extended interferometric 

synthetic aperture radar (InSAR) techniques initially developed in BOEM OCS Study 2012-067 to 

quantitatively classify landfast stability.

In-situ observations: We observed growth and melt of landfast ice by deploying seasonal ice mass 

balance buoys (SIMBs) near the communities of Point Hope and Utqiagvik. We also deployed acoustic 

Doppler current profilers (ADCPs) in an ice-tethered configuration to observe currents underneath the ice

Influence of storms on landfast ice: We used European Centre for Medium-Range Weather Forecasts 

version 5 (ERA) reanalysis sea level pressure (SLP) data to track storms systems quantify anomalies 

associated with landfast ice breakout events derived from the EM2024 dataset.

Numerical simulation of landfast sea ice: We implemented a basal shear stress parameterization in a 

MOM6-SIS2 coupled ice-ocean model to simulate the effect of ridge keels interacting with the seafloor in 

shallow water. Models runs were forced by JRA55-do atmospheric reanalysis data for the 25-year period 

from 1993–2017. 

RESULTS: 

The EM2024 dataset developed in Objective 1 of this study shows there are significant trends toward later 

formation of landfast ice across the region of up to 1.6 days yr-1

. We also find significant reductions in 

landfast ice extent of up to 0.27 km yr-1 in the Chukchi Sea and 0.74 km yr-1 in the Beaufort Sea, though
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the latter result could be influenced by ice charting practices used in the latter half of the record. We find 

that currently available InSAR products will likely be of limited value for routine ice charting practices, 

but they demonstrate that landfast ice stability generally increases with age.

Despite relatively few successful deployments and recoveries of in-situ instruments (Objective 2) data 

from one SIMB that captured a breakout event suggests that landfast ice may be experience less basal 

melt that adjacent drifting pack ice as long as it remains landfast.

Composite SLP fields derived from days associated with breakout events identified in the EM2024 data 

show significantly anomalous low pressures in the Bering Sea. A self-organizing map (SOM) analysis 

shows that the SLP pattern most commonly associated with breakout events corresponds to the 

occurrence of storms in the southern Bering Sea (Objective 3). 

Although the results to date from our MOM6-SIS2 model cannot be described as realistic simulations of 

landfast ice in the Arctic OCS, we demonstrate that this region is an ideal test ground for refining model 

parameter choices and the EM2024 dataset represents a valuable benchmark for quantifying model 

performance (Objective 4).

CONCLUSIONS: Landfast sea ice in the Arctic OCS has decreased significantly in both extent and duration 

over the past 27 years. Since the stability of landfast ice increases with age, a later start to landfast ice 

formation will likely result in reduced stability overall. Breakout events are significantly correlated with 

SLP anomalies in the southern Bering Sea and some coastal regions are more susceptible to breakouts 

than others. This suggests it may be possible to forecast periods of elevated breakout probability at local 

scales. 

STUDY PRODUCT(S):

1. BOEM study report: Mahoney AR, Bieniek P, Danielson S, Einhorn AH, Hedstrom KS, 

Jones JM, Klenz T (University of Alaska, Fairbanks, AK). 2024. Landfast ice climatology 

within the Arctic OCS. Anchorage (AK): U.S. Department of the Interior, Bureau of Ocean 

Energy Management. 121p. Report No.: OCS Study BOEM 2024-034. 

https://espis.boem.gov/Final%20Reports/BOEM_2024-034.pdf. 

2. MS Geophysics thesis: Einhorn AH. 2024. Continuous landfast ice climatology from 1996–

2023 and interferometric classification of landfast ice stability along the outer Alaska 

continental shelf [MS Thesis]. Fairbanks (AK): University of Alaska Fairbanks (July 2024). 

3. EM2024 Landfast ice climatology dataset: GeoTIFFs of daily landfast ice extent in the 

Arctic OCS for the period 1996–2023. 

4. Seasonal Ice Mass Balance Buoy (SIMB) Data: Comma-separated ASII files containing 

data from SIMBs deployed in landfast ice near Point Hope and Utqiagvik, Alaska. 

5. Acoustic Doppler Current Profiler (ADCP) Data: A binary file containing ADCP data 

from an under-ice deployment near Utqiagvik in 2022. 

6. Presentations (Poster and Oral):

Einhorn A, Mahoney A. 2023. Interferometric analysis of landfast sea ice breakouts occurring 

along the Alaska Outer Continental Shelf. In: Alaska Marine Science Symposium; 

January 23–27, 2023; Anchorage, Alaska. Anchorage (AK): North Pacific Research 

Board. p. 120. https://online.flippingbook.com/view/611616319/4/. 

Einhorn A, Mahoney A. 2024. Interferometric analysis of landfast sea ice stability along the 

outer Alaska continental shelf. In: Alaska Marine Science Symposium; January 29–

February 2, 2024; Anchorage, Alaska. Anchorage (AK): North Pacific Research Board. p. 

119. https://online.flippingbook.com/view/832931631/. 

Einhorn A, Mahoney A. 2024. Using interferometry to classify landfast sea ice extent and 

stability along the outer Alaska continental shelf. In: International Symposium on Sea Ice 

Across Temporal and Spatial Scales; June 4–9, 2023; Bremerhaven, Germany. Cambridge 

(UK): International Glaciological Society. p. 92A4328. https://www.igsoc.org/wp-
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content/uploads/2023/06/procabstracts_80.html#A4322. 

Hedstrom K, Hallberg R, Adcroft A, Danielson S, Curchister E, Mahoney A. 2024. Arctic 

ice-ocean circulation modeling: Evaluation of a landfast ice parameterization. In: Alaska 

Marine Science Symposium; January 29–February 2, 2024; Anchorage, Alaska. 

Anchorage (AK): North Pacific Research Board. p. 112. 

https://online.flippingbook.com/view/832931631/. 

Hedstrom K, Hallberg R, Danielson S, Curchitser E, Mahoney A. 2023. Arctic ice-ocean 

circulation modeling: recent improvements and applications. In: Alaska Marine Science 

Symposium; January 23–27, 2023; Anchorage, Alaska. Anchorage (AK): North Pacific 

Research Board. p. 119. https://online.flippingbook.com/view/611616319/4/. 

Hedstrom K, Mahoney A, Danielson S, Curchitser E, Hallberg R. 2022. Arctic ice-ocean 

circulation modeling: recent improvements and applications. In: Alaska Marine Science 

Symposium; January 24–27, 2022; Virtual Event. Anchorage (AK): North Pacific 

Research Board. p. 66. https://online.flippingbook.com/view/440241053/73/. 

Hedstrom K, Mahoney A, Danielson S, Curchitser E, Hallberg R. 2022. Arctic ice-ocean 

circulation modeling: recent improvements and applications. In: Ocean Sciences Meeting; 

February 24–March 4, 2022; Virtual Event. Washington (DC): American Geophysical 

Union. 

Jones J, Mahoney A, Bieniek P, Hedstrom K, Einhorn A, Danielson S. 2022. Toward 

forecasting landfast sea ice. In: Alaska Marine Science Symposium; January 24–27, 2022; 

Anchorage, Alaska. Anchorage (AK): North Pacific Research Board. p. 59. 

https://online.flippingbook.com/view/440241053/70/. 

Mahoney A, Bieniek P, Hedstrom K, Danielson S, Jones J. 2024. A multi-decadal dataset of 

landfast in the Alaska Arctic Outer Continental Shelf. In: Alaska Marine Science 

Symposium; January 29–February 2, 2024; Anchorage, Alaska. Anchorage (AK): North 

Pacific Research Board. p. 108. https://online.flippingbook.com/view/832931631/. 

Mahoney A, Einhorn A. 2022. Toward an updated climatology of landfast sea ice for the 

Alaska Outer Continental Shelf. In: Alaska Marine Science Symposium; January 24–27, 

2022; Virtual Event. Anchorage (AK): North Pacific Research Board. p. 63. 

https://online.flippingbook.com/view/440241053/70/. 

Mahoney A, Einhorn A, Bieniek P, Danielson S. 2024. Alaska landfast ice breakouts: large 

scale risk factors and early warnings. In: International Symposium on Sea Ice Across 

Temporal and Spatial Scales; June 4–9, 2023; Bremerhaven, Germany. Cambridge (UK): 

International Glaciological Society. p. 92A4322. https://www.igsoc.org/wpcontent/uploads/2023/06/procabstracts_80.html#A4322. 
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MAP OF STUDY AREA:

Figure 1: Map showing extent of the study areas used for analysis of landfast sea ice extent in this project. From OCS Study BOEM 2024-034 (Figure 1-2).