Ocean Basin and Lake Polygons for Sea Level Grids

This collection of files contains geographically registered polygons defining the shape of ocean basins and large lakes across the globe, designed for use in gridding and analysis of satellite-based observations of sea level. In particular, this data set was produced as part of the NASA-SSH (https://podaac.jpl.nasa.gov/NASA-SSH) effort, whose aim is to deliver continuously updated, climate-quality, global observations of sea level derived from radar altimeter observations. The polygons were derived using products from free vector and raster map data Natural Earth (https://naturalearthdata.com). Ocean basins were derived from version 5.1.0 of the 1:10m Marine Areas: https://www.naturalearthdata.com/downloads/10m-physical-vectors/ and Lakes were derived from version 5.0.0 of the 1:50m Lakes and Rivers polygons: https://www.naturalearthdata.com/downloads/50m-physical-vectors/ For the lakes, only the largest 26 lakes and inland seas were retained, as most smaller lakes are not typically sampled by traditional nadir altimeters. For the marine basins, some polygons were joined or sometimes split in order to simplify grouping altimeter data by regions where it is expected to be geographically correlated. For example, southern sections were split from the South Pacific and South Atlantic Oceans to simplify separation of these basins across the South American Peninsula. In addition to the polygons themselves, a table listing connections between polygons is also provided. This allows users to select observations in regions that are likely to be correlated over time scales of days to weeks or longer. Each polygon carries a unique numerical identifier (the Arctic Ocean is 1, the Southern Ocean is 2, etc…). For each identifier, the connection table lists all of the other identifiers that polygon is connected to. This is used in the NASA-SSH gridding process to down-select data used to estimate sea level at a specific location. Both the ocean and lake polygons themselves, and the connection table can be easily visualized in Google Earth (or other geographic mapping software) using the KMZ file provided. The connection table provides sets of polygons connected to each individual feature. For example, the Arctic Ocean polygon is connected to the Beaufort Sea, the Greenland Sea, the Barents Sea, etc. These can be easily visualized by turning on subsets of features in the Basin Connections folder within the KMZ file. Files contained in this dataset include: basin_files.tar.gz – a tar gzip file that contains a .dbf, .prj, .shx, and .shp Shape file that can be loaded into a geographic mapping program such as QGIS or Google Earth. This contains the polygon definitions, including their names. basin_name_table.txt – an ascii text file containing a list of all the basin ID numbers and simplified version of the basin names, separated by a colon “:”. A few basins were created for this dataset and do not have common geographic names. These are given names based on their ID number for example “Feature ID: 240”. basin_connection_table.txt – an ascii text file containing a list of all the basin ID numbers that are geographically connected to a given basin ID. The basin ID number in question is listed first on each row, and the connected ID numbers follow a colon “:”, in a comma separated list. NASA-SSH Basins.kmz – This KMZ file contains all of the polygon definitions, along with the set of polygons for each basin that shows which basins it is connected to. If loaded into Google Earth, it will create a folder in the Google Earth “Places” panel called “NASA-SSH Basins”. Below this, two subfolders will be created, one will be called “All Basin Polygons” and will contain all of the basins polygons colored red. Clicking on any one of the polygons will show the Basin ID number and name of this polygon. The second subfolder is called “Basin Connections” and contains a list of subfolders, one for each Basin ID. These can be turned on 1 at a time and will show a given basin polygon and all of the polygons it is connected to. If you use these data please cite: Willis, J.K., J. Sanchez, R. Santos, and S. Fournier, Ocean Basin and Lake Polygons for Sea Level Grids, at DOI:10.5281/zenodo.13910542.本文件集合包含全球范围内经地理配准的多边形数据，用于定义全球大洋盆地与大型湖泊的轮廓，专为海平面卫星观测数据的网格化处理与分析而设计。 具体而言，本数据集是NASA-SSH（https://podaac.jpl.nasa.gov/NASA-SSH）项目的产出成果之一，该项目旨在持续提供经气候质量认证的全球海平面观测数据，数据源自雷达高度计观测结果。 本数据集的多边形数据源自免费矢量与栅格地图数据平台Natural Earth（https://naturalearthdata.com）的相关产品。其中，大洋盆地数据取自Natural Earth 1:10m比例尺海洋区域数据集的5.1.0版本，下载地址：https://www.naturalearthdata.com/downloads/10m-physical-vectors/；湖泊数据则取自Natural Earth 1:50m比例尺湖泊与河流多边形数据集的5.0.0版本，下载地址：https://www.naturalearthdata.com/downloads/50m-physical-vectors/。 针对湖泊数据，仅保留了规模最大的26个湖泊与内陆海，因为传统天底指向雷达高度计通常无法覆盖绝大多数小型湖泊。针对大洋盆地数据，部分多边形经合并或拆分处理，以便按地理相关性较强的区域对高度计数据进行分组简化。例如，将南太平洋与南大西洋的南部区域拆分出来，以简化南美洲半岛两侧盆地的区分工作。 除多边形数据本身外，本数据集还附带一份多边形连接关系表，可帮助用户筛选出时间尺度为数日至数周甚至更长的相关区域观测数据。每个多边形均配有唯一的数值标识符（北冰洋为1，南大洋为2，依此类推）。针对每个标识符，连接关系表均列出了与之存在连接关系的其他所有标识符。该表在NASA-SSH网格化处理流程中用于筛选特定位置海平面估算所需的观测数据。 借助本数据集提供的KMZ文件，可在Google Earth（或其他地理制图软件）中直观展示大洋与湖泊多边形数据及连接关系表。连接关系表列出了与每个独立地理要素相连的多边形集合。例如，北冰洋多边形与波弗特海、格陵兰海、巴伦支海等区域相连。通过开启KMZ文件中「盆地连接关系」文件夹内的要素子集，即可直观展示这些连接关系。 本数据集包含以下文件： 1. basin_files.tar.gz：该tar.gz压缩包内含.dbf、.prj、.shx与.shp格式的Shapefile文件，可导入QGIS、Google Earth等地理制图软件，包含多边形定义及其名称信息。 2. basin_name_table.txt：该ASCII文本文件包含所有盆地ID编号与简化盆地名称的对应列表，以冒号「:」作为分隔符。本数据集新增了部分盆地，无通用地理名称，因此以其ID编号命名，例如"Feature ID: 240"。 3. basin_connection_table.txt：该ASCII文本文件列出了与指定盆地ID存在地理连接关系的所有盆地ID编号。每行首列为目标盆地ID编号，其后跟随冒号「:」与以逗号分隔的相连ID编号列表。 4. NASA-SSH Basins.kmz：该KMZ文件包含所有多边形定义，以及用于展示每个盆地连接关系的多边形集合。将其导入Google Earth后，会在Google Earth的「地点」面板中创建名为「NASA-SSH Basins」的文件夹，其下包含两个子文件夹：其一为「所有盆地多边形」，内含所有以红色标注的盆地多边形，点击任意多边形即可查看其盆地ID与名称；其二为「盆地连接关系」，包含按每个盆地ID划分的子文件夹，每次可开启一个子文件夹，以展示指定盆地多边形及其所有相连的多边形。 若使用本数据集，请引用以下文献： Willis, J.K.、J. Sanchez、R. Santos与S. Fournier，《用于海平面网格化的大洋盆地与湖泊多边形数据集》，DOI:10.5281/zenodo.13910542。