Geolocated sea-ice or snow surface elevation point cloud segments from helicopter-borne laser scanner during the MOSAiC expedition flight 20200611_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，用于表征海冰或雪面高程的时空演化过程，可用于绘制海冰干舷（freeboard）、表面粗糙度（roughness）、表面特征尺寸与空间分布等海冰状态相关参数。该表面高程数据以DTU21平均海平面高程为基准，且采集过程中未针对海冰漂移进行校正。数据采集搭载于直升机平台，采用近红外线扫描Riegl VQ-580机载激光扫描仪（持久标识符hdl:10013/sensor.7ebb63c3-dc3b-4f0f-9ca5-f1c6e5462a31 与 hdl:10013/sensor.7a931b33-72ca-46d0-b623-156836ac9550），沿MOSAiC漂流科考航线开展，采集时段为2019年9月至2020年10月，作业范围覆盖从拉普捷夫海北部横穿北冰洋中部、向弗拉姆海峡延伸的区域。飞行作业包含两种模式：小范围作业（约5×5公里网格测线，主要覆盖中部观测站区域），以及大范围作业（距离极星号（RV Polarstern）科考船数十公里范围，采用三角测线或断面测线模式）。点云数据以沿航迹的5分钟分段形式存储，采用自定义二进制格式；配套提供awi-als-toolbox（https://github.com/awi-als-toolbox/awi-als-toolbox）中的Python解析工具，以及对应的元数据JSON文件与测线快速预览PNG文件。该点云数据包含以下变量：以DTU平均海平面高程为基准的表面高程、表面反射率以及回波宽度。北纬85°以北区域的低质量GPS高程数据可能导致沿航迹表面高程出现起伏偏差，本数据产品未针对该偏差进行校正。