Merged grids of sea-ice or snow freeboard from helicopter-borne laser scanner during the MOSAiC expedition flight 20200227_01, version 1

This data set is a higher-processing-level version of Gridded segments of sea-ice or snow surface elevation and freeboard from helicopter-borne laser scanner during the MOSAiC expedition, version 1 (Hutter et al., 2022; doi:10.1594/PANGAEA.950339), where the individual 30-second segments of the small scale grid flights have been combined into merged grids. The data were collected using a near-infrared, line-scanning Riegl VQ-580 airborne laser scanner (hdl:10013/sensor.7ebb63c3-dc3b-4f0f-9ca5-f1c6e5462a31 & hdl:10013/sensor.7a931b33-72ca-46d0-b623-156836ac9550) mounted in a helicopter along the MOSAiC drift from the north of the Laptev Sea, across the central Arctic Ocean, and towards the Fram Strait from September 2019 to October 2020. The merged data are stored in netCDF and geotiff format. The data are drift corrected using the position and heading data of RV Polarstern and elevation offset corrected using overlapping segments to overcome degraded GPS altitude data >85°N. For the flights with degraded GPS altitude quality, we provide only a freeboard estimate. The merged grids include all data variables of the gridded 30-s segments: surface elevation, freeboard (estimate), freeboard uncertainty, estimated sea surface height, surface reflectance, echo width, and number of points used in the interpolation. Also the calculated elevation offset correction term is provided for each flight as a csv file.

本数据集为MOSAiC科考航次第1版机载激光扫描仪海冰/雪面高程与海冰干舷（freeboard）网格分段数据的高阶处理版本（Hutter等，2022；doi:10.1594/PANGAEA.950339），该版本将小型网格飞行采集的单条30秒分段数据合并为整合网格。本数据集采用搭载于直升机的近红外线扫描Riegl VQ-580机载激光扫描仪（hdl:10013/sensor.7ebb63c3-dc3b-4f0f-9ca5-f1c6e5462a31与hdl:10013/sensor.7a931b33-72ca-46d0-b623-156836ac9550）采集所得，采集时段为2019年9月至2020年10月，航线沿MOSAiC科考漂移轨迹，从拉普捷夫海北部出发，途经北冰洋中部，最终驶向弗拉姆海峡。整合后的数据以netCDF与GeoTIFF格式存储。针对北纬85°以上区域GPS高程数据质量下降的问题，本数据集采用‘极星’号（RV Polarstern）科考船的位置与航向数据完成漂移校正，并通过重叠分段完成高程偏移校正。对于GPS高程质量不佳的飞行航次，本数据集仅提供海冰干舷估算值。整合网格包含原始30秒网格分段的全部数据变量：包括表面高程、干舷（估算值）、干舷不确定性、估算海面高度、表面反射率、回波宽度以及插值所用的点数。此外，本数据集还为每个航次提供了以CSV格式存储的计算所得高程偏移校正项文件。