Ice velocity and thickness of the world's glaciers
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###Global mapping of surface ice flow velocity and ice thickness of glaciers around the world from Millan et al. (2022) The dataset presented here contains a global mapping of surface ice flow velocity and the ice thickness of glaciers around the world. Glacier surface flow velocities were calculated using *Sentinel-2/ESA*, *Landsat-8/USGS*, *Venμs/CNES-ISA*, *Pléiades/AirbusD&S* and radar data from *Sentinel-1/ESA*. *Reference and link to RGI*: The Randolph Glacier Inventory (RGI) is used to define the glacier outlines. This inventory provides global glacier outlines compiled from maps, aerial photographs and satellite images and can be found [here](https://www.glims.org/RGI/rgi60_dl.html). *Projections* : UTM (EPSG:326XX for the northern hemisphere and EPSG:327XX for the southern hemisphere) and Polar Stereographic (EPSG:3031 for Antarctica and EPSG:3414 for Greenland) Data are posted at 50 m horizontal spacing. Data are provided as geotiff `.tif` that can be opened in geographic information system. The naming convention is `VAR_RGI-X.Y_date.tif`, where: - `VAR` is the type of variable contained in the geotiff, - `RGI-X.Y` indicates the RGI region number with `X` (1 to 19) and sub-region with `Y`, and - `date` gives the date of the file generation. ###Ice velocity product Optical satellite images from [Landsat-8](https://www.usgs.gov/landsat-missions/landsat-8), [Sentinel-2](https://sentinel.esa.int/web/sentinel/missions/sentinel-2), [Venμs](https://venus.cnes.fr/fr) and synthetic aperture radar images from [Sentinel-1](https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-1) were used globally to map glacier surface flow velocity in 2017 and 2018. 5 different variables (`VAR`) are provided to describe : - `V` the magnitude of the ice velocity in m/year, - `VX` the component of velocity in m/year in x direction (east-west; positive toward east), - `VY` the component of velocity in m/year in y direction (north-sourth; positive toward north), - `STDX` the standard deviation of `VX` individual measurements in m/year, and - `STDY` the standard deviation of `VY` individual measurements in m/year. No data values are set to NaN and zero for all layers. Note : the ice velocity of the ice sheets are not provided here. The ice velocity map of Antarctica can be found here https://nsidc.org/data/NSIDC-0754/versions/1 , and the ice velocity map of Greenland can be found here https://nsidc.org/data/NSIDC-0646/versions/1 ###Ice thickness product Data are posted at 50 m horizontal spacing in georeferenced geotiff format `.tiff`. 2 different variables (`VAR`) are provided to describe : - `THICKNESS` the ice thickness model in m, - `ERRTHICKNESS` the estimated error on the ice thickness model in m Note : the ice thickness of glaciers connected to the coast or ice shelves of the Antarctic ice sheet are not provided here. Thickness map for these areas can be found here https://nsidc.org/data/NSIDC-0756/versions/1 Surface reference used : access the Arctic DEM at https://www.pgc.umn.edu/data/arcticdem/ ; the ASTER GDEM v3 is available at https://search.earthdata.nasa.gov and the TanDEM-X global DEM at https://geoservice.dlr.de
### 全球冰川表面流速与冰厚测绘数据集（源自Millan等人2022年研究） 本数据集包含全球范围内冰川的表面冰流速度与冰厚测绘结果。冰川表面流速通过*Sentinel-2/欧洲空间局（ESA）*、*Landsat-8/美国地质调查局（USGS）*、*Venμs/法国国家空间研究中心-空间与航空研究所（CNES-ISA）*、*Pléiades/空客防务与航天公司（AirbusD&S）*的数据以及*Sentinel-1/欧洲空间局（ESA）*的雷达数据计算得到。 *参考与兰道夫冰川编目（RGI）链接*：本数据集使用兰道夫冰川编目（Randolph Glacier Inventory，RGI）划定冰川轮廓。该编目收录了基于地图、航空摄影与卫星影像合成的全球冰川轮廓数据，可通过[此链接](https://www.glims.org/RGI/rgi60_dl.html)获取。 *投影方式*：采用通用横轴墨卡托投影（UTM，北半球对应EPSG:326XX，南半球对应EPSG:327XX）与极地方位等距投影（南极地区对应EPSG:3031，格陵兰地区对应EPSG:3414）。 数据水平分辨率为50米。 数据以地理标签图像文件格式（GeoTIFF，.tif）存储，可在地理信息系统中打开。文件命名规则为`VAR_RGI-X.Y_date.tif`，其中： - `VAR`表示地理栅格文件包含的变量类型， - `RGI-X.Y`代表RGI区域编号，`X`取值范围为1至19，`Y`为子区域编号， - `date`表示文件生成日期。 ### 冰流速产品 本产品基于[Landsat-8](https://www.usgs.gov/landsat-missions/landsat-8)、[Sentinel-2](https://sentinel.esa.int/web/sentinel/missions/sentinel-2)、[Venμs](https://venus.cnes.fr/fr)的光学卫星影像以及[Sentinel-1](https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-1)的合成孔径雷达影像，完成了2017与2018年全球冰川表面流速的测绘。 本次提供5种不同的变量（`VAR`）用于描述冰流速信息： - `V`：冰流速幅值，单位为米/年， - `VX`：流速的东-西向分量，单位为米/年，正向指向东， - `VY`：流速的北-南向分量，单位为米/年，正向指向北， - `STDX`：VX单次测量值的标准差，单位为米/年， - `STDY`：VY单次测量值的标准差，单位为米/年。 所有图层中的无数据值均设为NaN与0。 注意：本数据集未提供冰盖的冰流速数据。南极冰盖的冰流速图可通过[此链接](https://nsidc.org/data/NSIDC-0754/versions/1)获取，格陵兰冰盖的冰流速图可通过[此链接](https://nsidc.org/data/NSIDC-0646/versions/1)获取。 ### 冰厚产品 本产品的数据以地理配准的GeoTIFF格式（.tiff）存储，水平分辨率为50米。 本次提供2种不同的变量（`VAR`）用于描述冰厚信息： - `THICKNESS`：冰厚度模型结果，单位为米， - `ERRTHICKNESS`：冰厚度模型的估算误差，单位为米。 注意：本数据集未提供与南极冰盖沿海区域或冰架相连的冰川冰厚数据。此类区域的冰厚图可通过[此链接](https://nsidc.org/data/NSIDC-0756/versions/1)获取。 使用的地表参考数据：北极DEM可通过[此链接](https://www.pgc.umn.edu/data/arcticdem/)获取；ASTER GDEM v3可通过[此链接](https://search.earthdata.nasa.gov)获取；TanDEM-X全球DEM可通过[此链接](https://geoservice.dlr.de)获取。
