27 Jan 2023
 | 27 Jan 2023
Status: this preprint is currently under review for the journal TC.

Atmospheric highs drive asymmetric sea ice drift during lead opening from Point Barrow

MacKenzie E. Jewell, Jennifer K. Hutchings, and Cathleen A. Geiger

Abstract. Throughout winter, sea ice leads open episodically from headlands along the Alaskan coast under the winds of passing weather systems. As leads extend offshore into the Beaufort Sea, they produce ice velocity discontinuities that are challenging to represent in models. Here, we investigate how synoptic wind patterns form large-scale leads originating from Point Barrow, Alaska and influence Pacific Arctic sea ice circulation. We identify 135 leads from January–April 2000–2020 and generate an ensemble of lead opening sequences by averaging atmospheric conditions, ice velocity, and lead position across events. On average, leads open as the winds of migrating high-pressure systems drive differing ice-coast interactions across Point Barrow. Southward winds compress the Beaufort ice pack against the coast east of Point Barrow over several days, slowing sea ice drift. As offshore winds develop in the west, a lead opens and separates the western ice pack from the coast. The eastern ice pack remains in contact with the coast, drifting at half the rate of western ice despite similar wind speeds. As a result, sea ice drifts asymmetrically along the Alaskan coast during these events. Most events occur under north or east-northeast winds, and wind direction relative to the coast controls patterns of opening and ice drift. These findings highlight how coastal boundaries modify the response of the consolidated ice pack to wind forcing in winter. Observed connections between winds, ice drift, and lead opening provide effective test cases for sea ice models aiming to capture realistic ice transport during these recurrent events.

MacKenzie E. Jewell et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2023-9', Sascha Willmes, 27 Feb 2023
    • AC1: 'Reply on RC1', MacKenzie Jewell, 09 May 2023
  • RC2: 'Comment on tc-2023-9', Anonymous Referee #2, 29 Mar 2023
    • AC2: 'Reply on RC2', MacKenzie Jewell, 09 May 2023

MacKenzie E. Jewell et al.

Model code and software

Routine for extracting sea ice leads from MODIS imagery MacKenzie Jewell

MacKenzie E. Jewell et al.


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Short summary
Sea ice repeatedly fractures near a prominent Alaskan headland as winds move ice along the coast in winter, challenging predictions of sea ice drift. We find winds from high-pressure systems drive these fracturing events and the Alaskan coastal boundary modifies resultant ice drift. This observational study shows how wind patterns influence sea ice motion near coasts in winter. Identified relations between winds, ice drift and fracturing provide effective test cases for dynamic sea ice models.