Geolocated sea-ice or snow surface elevation point cloud segments from helicopter-borne laser scanner during the MOSAiC expedition flight 20200915_01, version 1

This data set provides high-resolution geolocated point clouds of sea-ice or snow surface elevation for mapping temporal and spatial evolution of sea-ice conditions such as freeboard, roughness, or the size and spatial distributions of surface features. The surface elevation data are referenced to the DTU21 mean sea surface height and are not corrected for sea-ice drift during acquisition. 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 flights are both small scale, ~5x5 km grid patterns mainly over the central observatory, and large scale, few tens of km away from RV Polarstern, triangle patterns, or transects. The point cloud data are stored in 5-min along-track segments in a custom binary format, for which we provide a python-based parsing tool in awi-als-toolbox (https://github.com/awi-als-toolbox/awi-als-toolbox), together with corresponding metadata json and line-shot quicklook png files. The point cloud data includes as variables: surface elevation (referenced to DTU mean sea surface height), surface reflectance, and echo width. The degraded GPS altitude data >85°N may cause undulations in the along-track surface elevations, which are not corrected for in this data product.

本数据集提供高分辨率地理定位点云数据，用于表征海冰或积雪表面高程的时空演化特征，涵盖海冰干舷、表面粗糙度，以及地表特征的尺寸与空间分布等海冰状态参数。该表面高程数据以DTU21平均海平面高度为基准，采集过程中未针对海冰漂移进行校正。数据采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 及 hdl:10013/sensor.7a931b33-72ca-46d0-b623-156836ac9550），于2019年9月至2020年10月期间，沿MOSAiC漂流观测航线开展，航线从拉普捷夫海北部出发，横穿北极中部，最终朝向弗拉姆海峡。飞行作业包含两类模式：小尺度作业为约5×5km的网格航线，主要覆盖中部观测站；大尺度作业则远离RV Polarstern号科考船，作业范围达数十公里，涵盖三角网格航线或断面测线。点云数据以5分钟沿轨分段的形式存储，采用自定义二进制格式。配套提供基于Python的解析工具awi-als-toolbox（https://github.com/awi-als-toolbox/awi-als-toolbox），以及对应的元数据JSON文件与航带快速预览PNG文件。该点云数据包含以下变量：表面高程（参考DTU平均海平面高度）、表面反射率与回波宽度。北纬85°以北区域的退化GPS高程数据可能引发沿轨表面高程起伏，本数据产品未对此类起伏进行校正。