Global Bathymetry and Elevation Digital Elevation Model: SRTM30_PLUS v8 (30 arc sec, 1 km) reformatted as single GeoTiff (NERP TE 13.1 eAtlas, source: UCSD)

This dataset corresponds to a reformatting of the SRTM30_PLUS digital elevation dataset from 33 NetCDF files into a single GeoTiff for use in GIS applications. No other modifications to the data were done. The rest of this metadata describes the original SRTM30_PLUS dataset itself.

This dataset is a 30-arc second resolution global topography/bathymetry grid (SRTM30_PLUS) developed from a wide variety of data sources. Land and ice topography comes from the SRTM30 and ICESat topography, respectively. Ocean bathymetry is based on a new satellite-gravity model where the gravity-to-topography ratio is calibrated using 298 million edited soundings. The main contribution of this dataset is the compilation and editing of the raw soundings, which come from NOAA, individual scientists, SIO, NGA, JAMSTEC, IFREMER, GEBCO, and NAVOCEANO.

The SRTM30_PLUS dataset developed by Scripps Institute Of Oceanography, University of California San Diego (UCSD).

Land data are based on the 1-km averages of topography derived from the USGS SRTM30 grided DEM data product created with data from the NASA Shuttle Radar Topography Mission. GTOPO30 data are used for high latitudes where SRTM data are not available.

Ocean data are based on the Smith and Sandwell global 1-minute grid between latitudes +/- 81 degrees. Higher resolution grids have been added from the LDEO Ridge Multibeam Synthesis Project, the JAMSTEC Data Site for Research Cruises, and the NGDC Coastal Relief Model. Arctic bathymetry is from the International Bathymetric Chart of the Oceans (IBCAO) [Jakobsson et al., 2003].

This data consists of 33 files of global topography in the same format as the SRTM30 products distributed by the USGS EROS data center. The grid resolution is 30 second which is roughly one kilometer. In addition the global data are also available in a single large file ready for GMT and as 33 NetCDF files. The eAtlas has also merged and formatted the data as a single GeoTiff file with overviews (1.6 GB).

The pixel-registered data are stored in 33 files with names corresponding to the upper left corner of the array shown below. The data are also merged into a single large (1.9 Gbyte, 2-byte integer) file as well as smaller 1-minute and 2-minute netcdf versions. Matching files of source identification number are available for determining the data source for every pixel.

This new version (v8.0) includes all of the multibeam bathymetry data collected by U.S. research vessels over the past three decades including 287 Scripps expeditions from research vessels Washington, Melville and Revelle. UCSD undergraduate student Alexis Shakas processed all the U.S. multibeam data and then worked with Google researchers on the global integration.

The data is available from UCSD FTP server as 33 NetCDF files and from the eAtlas as a merged GeoTiff.

If you are after high resolution bathymetry/elevation data for regional areas please check the related links.

Reference, sounding data:
Becker, J. J., D. T. Sandwell, W. H. F. Smith, J. Braud, B. Binder, J. Depner, D. Fabre, J. Factor, S. Ingalls, S-H. Kim, R. Ladner, K. Marks, S. Nelson, A. Pharaoh, R. Trimmer, J. Von Rosenberg, G. Wallace, P. Weatherall., Global Bathymetry and Elevation Data at 30 Arc Seconds Resolution: SRTM30_PLUS, Marine Geodesy, 32:4, 355-371, 2009. http://topex.ucsd.edu/sandwell/publications/124_MG_Becker.pdf

Reference, gravity data:
Sandwell, D. T., and W. H. F. Smith, Global marine gravity from retracked Geosat and ERS-1 altimetry: Ridge Segmentation versus spreading rate, J. Geophys. Res., 114, B01411, doi:10.1029/2008JB006008, 2009. http://dx.doi.org/10.1029/2008JB006008

eAtlas Processing:

A set of Batch scripts were developed to perform the conversion of the data from NetCDF to GeoTiff and the generation of the hillshading. This processing was based on the GDAL command line tools. Full details of the processing can be found in the downloadable Scripts associated with this dataset.

Data Location:

This dataset is filed in the eAtlas enduring data repository at: data\NERP-TE\13.1_eAtlas\World_UCSD_SRTM30-plus

本数据集为将SRTM30_PLUS数字高程数据集从33个网络通用数据格式（NetCDF）文件重新格式化为单个地理标记图像文件格式（GeoTIFF）文件，以适配地理信息系统（GIS）应用场景，未对原始数据进行任何额外修改。本元数据的其余内容用于描述原始的SRTM30_PLUS数据集本身。

本数据集为采用多源数据构建的30角秒分辨率全球地形/水深网格（SRTM30_PLUS）。其中，陆地与冰面地形分别源自SRTM30与冰云和陆地高程卫星（ICESat）地形数据；海洋水深则基于全新的卫星重力模型，该模型通过2.98亿条经过编辑的测深数据对重力-地形比进行了校准。本数据集的核心贡献在于对源自美国国家海洋和大气管理局（NOAA）、独立科研人员、斯克里普斯海洋研究所（SIO）、美国国家地理空间情报局（NGA）、日本海洋研究开发机构（JAMSTEC）、法国海洋开发研究院（IFREMER）、国际海洋学数据和信息交换委员会（GEBCO）以及美国海军海洋局（NAVOCEANO）的原始测深数据进行了整合与编辑。

本SRTM30_PLUS数据集由加利福尼亚大学圣迭戈分校斯克里普斯海洋研究所（UCSD）研发。

陆地数据源自美国地质调查局（USGS）基于美国国家航空航天局（NASA）航天飞机雷达地形测绘任务（SRTM）数据生成的SRTM30格网数字高程模型（DEM）产品，经1公里平均重采样得到；在无SRTM数据覆盖的高纬度区域，则采用GTOPO30数据补充。

海洋数据以Smith与Sandwell生成的纬度±81°范围内的1分分辨率全球格网数据为基础；额外补充了拉蒙特-多尔蒂地球观测台（LDEO）洋中脊多波束合成项目、日本海洋研究开发机构科考数据站点以及美国国家地球物理数据中心（NGDC）海岸地形模型的高分辨率格网数据。北极海域水深数据源自《国际海洋水深图》（IBCAO）[Jakobsson等，2003]。

本数据集包含33份全球地形文件，格式与美国地质调查局地球资源观测与科学中心（USGS EROS）分发的SRTM30产品一致。其格网分辨率为30角秒，约合1公里。此外，全球数据还可获取为单个适配通用制图工具（GMT）的大型文件，以及33个网络通用数据格式（NetCDF）文件。eAtlas平台还将数据整合并格式化为单份带概览图的GeoTIFF文件，大小约1.6GB。

本数据集的像素配准数据以33个文件存储，文件名与下述数组的左上角坐标对应。数据同时被整合为单个大型（1.9GB，2字节整型）文件，以及分辨率为1分、2分的小型网络通用数据格式（NetCDF）版本。此外还提供匹配的数据源标识号文件，可用于查询每个像素对应的原始数据来源。

本数据集的8.0版本包含了过去三十年间美国科考船收集的所有多波束测深数据，其中包括斯克里普斯研究所利用“华盛顿号”“梅尔维尔号”与“雷维尔号”科考船完成的287次科考任务数据。加利福尼亚大学圣迭戈分校本科生Alexis Shakas完成了所有美国多波束数据的处理工作，随后与谷歌（Google）科研人员合作完成了全球数据整合。

用户可通过加利福尼亚大学圣迭戈分校FTP服务器获取33个网络通用数据格式（NetCDF）的原始数据文件，也可通过eAtlas平台获取整合后的地理标记图像文件格式（GeoTIFF）文件。

若您需要特定区域的高分辨率地形/水深数据，请查阅相关链接。

### 测深数据参考文献：
Becker, J. J.、D. T. Sandwell、W. H. F. Smith、J. Braud、B. Binder、J. Depner、D. Fabre、J. Factor、S. Ingalls、S-H. Kim、R. Ladner、K. Marks、S. Nelson、A. Pharaoh、R. Trimmer、J. Von Rosenberg、G. Wallace、P. Weatherall. 《30角秒分辨率全球水深与高程数据集：SRTM30_PLUS》，《海洋大地测量学》，32卷第4期，355-371页，2009年。http://topex.ucsd.edu/sandwell/publications/124_MG_Becker.pdf

### 重力数据参考文献：
Sandwell, D. T.与W. H. F. Smith，《基于重跟踪Geosat与ERS-1测高数据的全球海洋重力场：洋中脊分段与扩张速率》，《地球物理学研究杂志》，114卷，B01411，DOI:10.1029/2008JB006008，2009年。http://dx.doi.org/10.1029/2008JB006008

### eAtlas处理流程：
本数据集开发了一套批处理脚本，用于将网络通用数据格式（NetCDF）数据转换为地理标记图像文件格式（GeoTIFF）格式，并生成山体阴影图层。该处理流程基于地理空间数据抽象库（GDAL）命令行工具实现，详细处理步骤可参阅本数据集附带的可下载脚本文件。

### 数据存储位置：
本数据集存储于eAtlas持久化数据仓库中，路径为：data\NERP-TE\13.1_eAtlas\World_UCSD_SRTM30-plus