Supplementary material to "The effect of changing sea ice on nearshore wave climate trends along Alaska’s central Beaufort Sea coast"

Abstract. Diminishing sea ice is impacting the wave field across the Arctic region. Recent observation and model-based studies highlight the spatiotemporal influence of sea ice on offshore wave climatologies, but effects within the nearshore region are still poorly described. This study characterizes the wave climate in the central Beaufort Sea coast from 1979 to 2019 by utilizing a wave hindcast model that uses ERA5 winds, waves, and ice concentrations as input. The spectral wave model SWAN is calibrated and validated based on more than 10,000 in situ measurements collected over a 13-year time period across the region, with friction variations and empirical coefficients for newly implemented empirical ice formulations for the open water season. Model results and trends are analyzed over the 41-year time period using the non-parametric Mann-Kendall test, including an estimate of Sen’s slope. The model results show that the reduction of sea ice concentration correlates strongly with increases in average and extreme wave conditions. In particular, the open water season extended by ~96 days over the 41-year time period (~2.4 days/yr), resulting in a five-fold increase of the yearly cumulative wave power. Moreover, the open water season extends later into the year, resulting in relatively open-water conditions during fall storms with high wind speeds. The later freeze-up results in an increase of the annual offshore median wave heights of 1 % per year and an increase in the average number of rough wave days (defined as days when maximum wave heights exceed 2.5 m) from 1.5 in 1979 to 13.1 days in 2019. Trends in the nearshore areas deviate from the patterns offshore. Model results indicate a non-breaking depth-induced saturation limit for high wave heights in the shallow areas of Foggy Island Bay. Similar patterns are found for yearly cumulative wave power.

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Evaluation of PAZ satellite imagery for the assessment of intra-seasonal dynamics of permafrost coasts (Beaufort Sea, Canada)

10.5194/egusphere-egu21-15632 ◽

2021 ◽

Author(s):

Carla Mora ◽

Gonçalo Vieira ◽

Pedro Pina ◽

Dustin Whalen ◽

Annett Bartsch

Keyword(s):

High Resolution ◽

Sea Ice ◽

Tide Gauge ◽

Beaufort Sea ◽

Arctic Sea Ice ◽

The Arctic ◽

Coastal Monitoring ◽

Horizon 2020 ◽

Coastal Changes ◽

Sea Coast

<p>Arctic permafrost coasts represent about 34% of the Earth&#8217;s coastline, with long sections affected by high erosion rates, increasingly threatening coastal communities. Year-round reduction in Arctic sea ice is forecasted and by the end of the 21st century, models indicate a decrease in sea ice area from 43 to 94% in September and from 8 to 34% in February (IPCC, 2014). An increase of the ice-free season leads to a longer exposure to wave action. Monitoring the Arctic coasts is limited by remoteness, climate harshness and difficulty of access for direct surveying, but also, when using satellite remote sensing, by frequent high cloudiness conditions and by illumination. In order to overcome these limitations, three sites at the Beaufort Sea Coast (Clarence lagoon, Hopper Island and Qikiqtaruk/Herschel Island) have been selected for monitoring using very high-resolution microwave X-band spotlight PAZ imagery from Hisdesat. Bluff top, thaw-slump headwalls and water lines were digitised from images acquired during the ice-free seasons of 2019 and 2020 at sub-monthly time-steps. The effects of coastal exposure on delineation accuracy in relation to satellite overpass geometry have been assessed and coastal changes have been quantified and compared to meteorological and tide-gauge data. The results show that PAZ imagery allow for monitoring and quantifying coastal changes at sub-monthly intervals and following the evolution of coastal features, such as small mud-flow fans and retrogressive thaw slumps. This shows that high resolution microwave imagery has a strong potential for significantly advancing coastal monitoring in remote Arctic areas. This research is part of project Nunataryuk funded under the European Union's Horizon 2020 Research and Innovation Programme (grant agreement no. 773421) and of Hisdesat project Coastal Monitoring for Permafrost Research in the Beaufort Sea Coast (Canada).&#160;</p>

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Mass Balance of Multiyear Sea Ice in the Southern Beaufort Sea

10.21236/ada572179 ◽

2012 ◽

Author(s):

Andrew R. Mahoney

Keyword(s):

Sea Ice ◽

Mass Balance ◽

Beaufort Sea

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Mass Balance of Multiyear Sea Ice in the Southern Beaufort Sea

10.21236/ada617624 ◽

2014 ◽

Author(s):

Andrew R. Mahoney

Keyword(s):

Sea Ice ◽

Mass Balance ◽

Beaufort Sea

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Albedo of Melting Sea Ice in the Southern Beaufort Sea

Journal of Glaciology ◽

10.3189/s0022143000013022 ◽

1971 ◽

Vol 10 (58) ◽

pp. 101-104 ◽

Cited By ~ 1

Author(s):

M.P. Langleben

Keyword(s):

Sea Ice ◽

Northwest Territories ◽

Beaufort Sea ◽

Ice Cover ◽

Short Wave ◽

Wave Radiation ◽

Short Wave Radiation ◽

Melting Period ◽

Fast Ice ◽

Made In

AbstractTwo Kipp hemispherical radiometers mounted back to back and suspended by an 18 m cable from a helicopter flying at an altitude of about 90 m were used to make measurements of incident and reflected short-wave radiation. The helicopter was brought to a hovering position at the instant of measurement to ensure that the radiometers were in the proper attitude and a photograph of the ice cover was taken at the same time. The observations were made in 1969 during 16 flights out of Tuktoyaktuk, Northwest Territories (lat. 69° 26’N., long. 133° 02’W.) over the fast ice extending 80 km north of Tuktoyaktuk. Values of albedo of the ice cover were found to decrease during the melting period according to the equation A = 0.59 —0.32P where P is the degree of puddling of the surface.

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