SA Agulhas II Winter 2017 Cruise: ice edge drifters

Three Trident Sensors Helix beacons (Unit 1,2,3) were deployed about on ice floes close to latitude 62.8 S and longitude 29.8 E on 4th July 2017 to measure sea ice drift.The region where the instruments were deployed (Antarctic Marginal Ice Zone) consisted of first-year ice on average ~50 cm thick. The instruments were deployed by hand by three people, lowered by crane from the ship to the ice on a basket cradle on floes ~5 m in diameter.The temporal resolution is 4 hours. The survival of the sensors depended on staying fixed to the floe and the battery life.Unit 1 provided GPS location from the 5th July 2017 to 1st December 2017, started at 62.84 S and 30.20 E and finished at 61.55 S and 55.99 E.Unit 2 provided GPS location from the 5th July 2017 to 3rd August 2017, started at 62.83 S and 30.20 E and finished at 62.36 S and 31.57 E.Unit 3 provided GPS location from the 5th July 2017 to 15st August December 2017, started at 62.59 S and 29.98 E and finished at 61.16 S and 35.60 E.In the .xlsx submission sheet 1 refers to Unit 1, sheet 2 to Unit 2, and sheet 3 to Unit 3.First column is the Unit Identifier (1,2,3)Second column is the date in the format day/month/yearThird column is the UTC time in the format hh:mm:ssFourth column is the latitude in degrees and decimals, the negative refers to SouthFifth column is the longitude in degrees and decimals, the positive refers to East

三台搭载三叉戟传感器（Trident Sensors）的螺旋信标（Unit 1、2、3）于2017年7月4日部署在南纬62.8°、东经29.8°附近的浮冰上，用于监测海冰漂移。该部署区域为南极边缘冰区（Antarctic Marginal Ice Zone），整体以平均厚度约50厘米的一年冰为主。本次部署由三名人员手工完成，通过船上起重机将搭载于直径约5米浮冰吊篮中的仪器下放至冰面。本数据集的时间分辨率为4小时。传感器的存活状态取决于其是否牢固固定于浮冰以及电池续航能力。

单元1的GPS定位数据采集时段为2017年7月5日至2017年12月1日，起始坐标为南纬62.84°、东经30.20°，终止坐标为南纬61.55°、东经55.99°。

单元2的GPS定位数据采集时段为2017年7月5日至2017年8月3日，起始坐标为南纬62.83°、东经30.20°，终止坐标为南纬62.36°、东经31.57°。

单元3的GPS定位数据采集时段为2017年7月5日至2017年8月15日（原文存在笔误，原表述为“15st August December 2017”），起始坐标为南纬62.59°、东经29.98°，终止坐标为南纬61.16°、东经35.60°。

在提交的.xlsx文件中，工作表1对应单元1，工作表2对应单元2，工作表3对应单元3。各列字段说明如下：第一列为单元标识符（取值为1、2、3）；第二列为日期，格式为日/月/年；第三列为UTC时间，格式为hh:mm:ss；第四列为纬度（度及小数位），负值代表南纬；第五列为经度（度及小数位），正值代表东经。