Sea-ice freeboard derived from airborne laser scanner

The dataset submitted here is 'Sea-ice freeboard derived from airborne laser scanner'. Between 2007 and 2012, the Australian Antarctic program operated a scanning LiDAR system and other scientific instruments for sea-ice geophysical surveys in East Antarctica. For example see Lieser et al. [2013] for the 2012 survey. The dataset here provides the sea-ice freeboard (i.e. elevation above sea level) along various helicopter flight lines of the 2012 survey in the sea-ice zone between 113 degE and 123 degE. The data collection was based on: - Riegl LMS Q240i-60 scanning LiDAR, measuring sea ice elevation above the WGS84 reference ellipsoid; - Hasselblad H3D II 50 camera, taking aerial photographs at about 13 cm resolution every 3-5 seconds (older digital camera used in 2007); - inertial navigation and global positioning system, OxTS RT-4003. The following geophysical corrections were applied to the sea-ice elevations to derive the sea-ice freeboard: - geoid correction (from the EGM2008 Earth gravity model); - mean ocean dynamic topography correction (from the DTU Space model - DTU10MDT); - ocean tide correction (from the Earth and Space Research CATS2008 Antarctic tide model); - atmospheric pressure (inverse barometer effect) correction from ECMWF data (4-year average) and ship-board underway observations. The geophysical corrections have been validated along selected flight lines by extracting ocean surface elevations from leads between ice floes as identified in the aerial photography. Contained in this dataset are the following files: - a netCDF file for 8 selected flights of the 2012 survey containing sea-ice freeboard values; - a postscript file for 4 of the 8 selected flights showing the residuals from the applied geophysical corrections. These 4 flights were selected on the basis of having a good spread of observable leads along the entire flight line that enabled the extraction of ocean surface elevations.本次提交的数据集为《机载激光扫描仪获取的海冰干舷（Sea-ice freeboard derived from airborne laser scanner）》。 2007至2012年间，澳大利亚南极科考项目在东南极洲开展海冰地球物理勘测期间，搭载了扫描式激光雷达（scanning LiDAR）及其他科学仪器。相关2012年勘测的详情可参阅Lieser等人[2013]的研究。本数据集提供了2012年勘测中，东经113°至123°海冰区域内多条直升机飞行航线对应的海冰干舷（即海平面以上海拔高度）数据。 本次数据采集基于以下设备： - Riegl LMS Q240i-60扫描式激光雷达，用于测量基于WGS84参考椭球的海冰海拔高度； - 哈苏（Hasselblad）H3D II 50相机，以约13厘米的分辨率每3至5秒拍摄一张航空照片（2007年勘测使用的为老旧数码相机）； - 惯性导航与全球定位系统OxTS RT-4003。 为推导海冰干舷，已对海冰海拔数据施加如下地球物理校正： - 大地水准面校正（基于EGM2008地球重力模型）； - 平均海洋动力地形校正（基于DTU Space模型——DTU10MDT）； - 海洋潮汐校正（基于地球与空间研究中心的CATS2008南极潮汐模型）； - 基于ECMWF数据（4年平均值）与船舶连续观测数据的大气压力（反气压效应）校正。 上述地球物理校正已通过从航空摄影识别的浮冰间水道提取洋面海拔数据，在选定飞行航线上完成了验证。 本数据集包含以下文件： - 对应2012年8条选定飞行航线的netCDF文件，内含海冰干舷数值； - 对应上述8条选定航线中4条的PostScript文件，展示了所施加地球物理校正后的残差。选取该4条航线的依据为：其整条航线上分布有充足且可观测的水道，可用于提取洋面海拔数据。