ASPeCt bridge-based sea-ice observations – Ross Sea, Autumn 2025

The Antarctic Sea ice Processes and Climate [ASPeCt] data sets submitted here have been collected systematically from the bridge of the Xue Long II, CHINARE icebreaker, while it transited through pack ice during the JTRES voyage in the autumn of 2025.Quantifiable observations of sea-ice thickness and related characteristics of the sea ice, snow, ocean and surface atmosphere were recorded hourly while the vessel moved through the sea-ice zone. When the vessel was stopped or had not moved at least 6nm since the previous observation, no observations were made. The observation protocol was endorsed by the Scientific Commission for Antarctic Research (under their ASPeCt EG programme) as the preferred method for conducting ship-based observations of sea-ice characteristics. Details can be found in Worby and Allison [1999].The relevant spreadsheets (csv file) contains the following information: Header name; Physical parameter; UnitYear; Year    Date; Day/Month/Year    Julian Day; Day of year    Time (UT); Time of day in Universal time: Hours/Minutes/Seconds    Lat (degrees N); Latitude; degrees NLon(degrees E); Longitude; degrees EConc; Total ice concentration; TenthOW; Open-water classification; See Worby and Allison [1999]c1; Ice concentration of primary ice category; Tenthty1; Ice type of primary ice category; See Worby and Allison [1999]iz1; Thickness of primary ice category; cmf1; Floe size of primary ice category; See Worby and Allison [1999]t1; Topography of primary ice category; See Worby and Allison [1999]s1; Snow type on primary ice category; See Worby and Allison [1999]sz1; Snow thickness on primary ice category; cmc2; Ice concentration of secondary ice category; Tenthty2; Ice type of secondary ice category; See Worby and Allison [1999]iz2; Thickness of secondary ice category; cmf2; Floe size of secondary ice category; See Worby and Allison [1999]t2; Topography of secondary ice category; See Worby and Allison [1999]s2; Snow type on secondary ice category; See Worby and Allison [1999]sz2; Snow thickness on secondary ice category; cmc3; Ice concentration of tertiary ice category; Tenthty3; Ice type of tertiary ice category; See Worby and Allison [1999]iz3; Thickness of tertiary ice category; cmf3; Floe size of tertiary ice category; See Worby and Allison [1999]t3; Topography of tertiary ice category; See Worby and Allison [1999]s3; Snow type on tertiary ice category; See Worby and Allison [1999]sz3; Snow thickness on tertiary ice category; cmSea; Sea-surface temperature; degrees CAir; Surface-air temperature; degrees CReference: Worby, A.P., and I. Allison, A Technique for Making Ship-Based Observations of Antarctic Sea Ice Thickness and Characteristics, PART I Observational Technique and Results, Antarctic CRC Report No. 14, ISBN: 1 875796 09 6, 1999.