Hydrographic survey HI634 by the RAN Australian Hydrographic Service at Davis, February 2020

The Australian Antarctic Division identified areas that required hydrographic surveying. (See map available in the download at \Plans and Instructions\HPS Supplied Data\davis_plan_2019_2020 version 5.1.pdf and a shapefile of the identified areas at FSD\ArcGIS\Pink V2\AOI_Unproject_wgs84.shp) A team from the Maritime Geospatial Warfare Unit, of the Australian Hydrographic Service, was at Davis in early February 2020. Single beam and side scanning survey data was collected on the water, beach profiles collected and rock data. Single beam and side scanning survey dataAreas A, D, F, H, I, J and K were ice free.Area J was further broken down into four areas, J1, J2, J3 and J4.Areas A, D and F were thoroughly surveyed with 10m mainline spacing with 20m X-line spacing.Areas I, J3 and J4 were surveyed but due to time constraints were surveyed at approximately 40m line spacing to provide 200% sea floor coverage with the SSS to detect any features dangerous to navigation with one shoal detected in area I which is mentioned in Section I.Area H was too shallow to survey at any other time except high tide and it was decided to focus on other areas as the survey of this area would not value add to the required results of the survey.Area J1, J2 and K were not surveyed due to time constraints. RTK corrections or access to the CORS network couldn't be made to the CEESCOPE survey system. Instead positioning during the survey was recorded exclusively with the NovaTel GNSS 850 Antenna. No post processing was conducted. The team wasn't able to determine why the CEESCOPE was unable to connect to the CORS network or Base Station to gain RTK corrections, despite considerable effort spent problem solving and conducting a number of trials. Tide data collected was applied to the data and all tidal information is explained in section F of the report. A map showing the surveyed areas can be found in the report. Raw data in caris format is available from the Australian Hydrographic Office (AHO). Sounding data, stored as a shapefile, is available as a download file.Beach profilesSites were also surveyed with 5m line spacing to maximise seafloor coverage, at 5 beach locations, 4 in area A and 1 in Area F. ArcGIS projects and PDF documents displaying the depth data and significant rocks are included in the download. Please note the ArcGIS projects do not include the AHO chart, due to distribution restrictions on digital charts. It is included in the PDF documents. These documents refer to images taken from the survey boat and spreadsheets displaying gradients data. Rock dataA shapefile recording conspicuous rocks as well as photographs is available for downloading. Bench mark positions were reclaimed using Trimble R10 and post processed with AUSPOS. Abbreviations used in the download directories ROS = Report of Survey, FSD = Final Survey Data A detailed report can be found at /ROS/Projection……..…...…...………….….……..Universal Transverse Mercator (UTM) Zone 43 SouthHorizontal Datum……………………………World Geodetic System 1984 (WGS84)Vertical Datum…………………………….....Approximated Lowest Astronomical Tide (LAT)Sounding Depths.……………………………Metres (m) Survey Date………………..………………….6th - 18th Feb 2020Bathymetric Accuracy Horizontal……………± 0.8mBathymetric Accuracy Vertical………………±0.46mSounding Density……………………………..2m SurfaceChart Reference………………………………AUS 451, 602​ITRF 2014 and GRS80 were utilised for static observations of bench marks and levelling to the tide pole for establishment of approximate LAT. Hypack v19.1.11.0 which was used to gather all bathymetric data does not have the option to use the ITRF datum and the WGS84 Datum was used.

澳大利亚南极局（Australian Antarctic Division）划定了需开展水文测量的区域。（可在下载路径Plans and InstructionsHPS Supplied Datadavis_plan_2019_2020 version 5.1.pdf中查看相关地图，划定区域的形状文件（shapefile）可于FSDArcGISPink V2AOI_Unproject_wgs84.shp获取）

澳大利亚水文服务局（Australian Hydrographic Service）下属的海洋地理空间作战单元（Maritime Geospatial Warfare Unit）工作组于2020年2月初进驻戴维斯南极科考站。本次于水上作业采集单波束与侧扫声呐测量数据，并完成海滩剖面数据采集与礁石数据收集。

单波束与侧扫声呐测量覆盖区域：区域A、D、F、H、I、J及K均无海冰覆盖。其中J区域被进一步划分为J1、J2、J3与J4四个子区域。

区域A、D及F采用10米主线间距与20米侧线间距开展了全面测量。区域I、J3及J4虽已完成测量，但受时间限制，仅采用约40米的测线间距作业，以通过侧扫声呐（Side Scan Sonar，SSS）实现200%的海底覆盖，从而探测对航行构成威胁的水下障碍物；本次在区域I内探测到一处浅滩，相关内容详见报告第I节。

区域H水深过浅，仅能在高潮时段开展测量，且经评估，对该区域的测量无法为本次作业的预期成果带来附加价值，因此工作组决定优先开展其他区域的测量工作。受时间限制，区域J1、J2及K未开展测量作业。

CEESCOPE测量系统无法获取实时动态差分（Real-Time Kinematic，RTK）修正数据，亦无法接入连续运行参考站（Continuously Operating Reference Stations，CORS）网络。因此，本次测量期间仅通过诺瓦泰（NovaTel）GNSS 850天线进行定位数据记录，未开展任何后处理工作。尽管工作组投入了大量精力开展问题排查与多组测试，但仍未能查明CEESCOPE系统无法接入CORS网络或基准站以获取RTK修正数据的原因。

本次采集的潮位数据已应用于测量数据处理，所有潮位相关信息详见报告第F节。报告中包含一张标示已测量区域的地图。

卡里斯（CARIS）格式的原始数据可从澳大利亚水文办公室（Australian Hydrographic Office，AHO）获取。以形状文件（shapefile）存储的测深数据可作为下载文件获取。

海滩剖面数据：本次在5处海滩点位开展了海滩剖面测量，其中区域A内4处、区域F内1处，测线间距设为5米以最大化海底覆盖范围。下载包中包含ArcGIS项目文件与PDF文档，用于展示测深数据与重要礁石信息。需注意，由于数字海图的分发限制，ArcGIS项目文件未包含澳大利亚水文办公室（AHO）的海图，该海图已收录于PDF文档中。上述文档中包含测量船拍摄的影像，以及展示梯度数据的电子表格。

礁石数据：包含醒目礁石信息与对应照片的形状文件（shapefile）可下载获取。基准点位置采用天宝（Trimble）R10接收机进行复测，并通过澳大利亚精密单点定位服务（AUSPOS）完成后处理。

下载目录中使用的缩写说明：ROS=测量报告（Report of Survey），FSD=最终测量数据（Final Survey Data）。详细报告可于/ROS/Projection路径下获取。

## 测量基准与参数
通用横轴墨卡托（Universal Transverse Mercator，UTM）43南带
水平基准面……………………………1984世界大地坐标系（World Geodetic System 1984，WGS84）
垂直基准面……………………………近似最低天文潮（Approximated Lowest Astronomical Tide，LAT）
测深单位………………………………米（m）
测量日期………………………………2020年2月6日至18日
水深测量水平精度…………………±0.8米
水深测量垂直精度…………………±0.46米
测深密度………………………………2米（水面测点间距）
海图参考编号…………………………AUS 451、602

基准点静态观测与潮位杆水准测量采用国际 Terrestrial Reference Frame 2014（ITRF 2014）与GRS80椭球参数，以构建近似最低天文潮基准。本次所有水深数据均通过Hypack v19.1.11.0软件采集，由于该软件不支持ITRF基准，因此采用WGS84基准。