A dataset of landfast ice extent along the Alaska coast of the Chukchi Sea and adjacent waters in Russia, spanning the winters of 1996-2023. Landfast ice extent is defined as the area between the coast and the seaward landfast ice edge (SLIE), meaning that small areas of open water than can form at the coast springtime will not be represented. Spatial resolution is 100 m. Compilation of the dataset is described in detail by Mahoney et al (2024). In brief, it is derived from three sources: From 1996-2008, the dataset is derived from analysis of sequential synthetic aperture radar (SAR) images from the RadarSAT and EnviSAT constellations, as described by Mahoney et al (2014); From 2008-2023, the data represent an average landfast extent identified in ice charts from the U.S. National Weather Service Alaska Sea Ice Program (ASIP) and the U.S. National Ice Center (NIC).

Within each GeoTIFF file there are 5 different pixel values representing different characteristics:

0 - Not Landfast Ice

32 - Coast Vector Shadow

64 - Out of Bounds

128 - Land

255 - Landfast ice

The file naming convention is as follows:

chukchi_$YYYYMMDD_$source_slie.tif

For example, the name

chukchi_20170302_asip_and_nic_average_slie.tif

indicates the file represents data for March 2, 2017 and that the data is derived from an average of the ASIP and NIC data sources.