GEDI L2B Canopy Cover and Vertical Profile Metrics Data Global Footprint Level V002

The Global Ecosystem Dynamics Investigation (GEDI) ) mission aims to characterize ecosystem structure and dynamics to enable radically improved quantification and understanding of the Earth’s carbon cycle and biodiversity. The GEDI instrument produces high resolution laser ranging observations of the 3-dimensional structure of the Earth. GEDI is attached to the International Space Station (ISS) and collects data globally between 51.6° N and 51.6° S latitudes at the highest resolution and densest sampling of any light detection and ranging (lidar) instrument in orbit to date. Each GEDI Version 2 granule encompasses one-fourth of an ISS orbit and includes georeferenced metadata to allow for spatial querying and subsetting.

The purpose of the GEDI Level 2B Canopy Cover and Vertical Profile Metrics product (GEDI02_B) is to extract biophysical metrics from each GEDI waveform. These metrics are based on the directional gap probability profile derived from the L1B waveform. Metrics provided include canopy cover, Plant Area Index (PAI), Plant Area Volume Density (PAVD), and Foliage Height Diversity (FHD). The GEDI02_B product is provided in HDF5 format and has a spatial resolution (average footprint) of 25 meters.

The GEDI02_B data product contains 96 layers for each of the eight-beam ground transects (or laser footprints located on the land surface). Datasets provided include precise latitude, longitude, elevation, height, canopy cover, and vertical profile metrics. Additional information for the layers can be found in the GEDI Level 2B Data Dictionary.

Improvements for Version 2
* Metadata has been updated to include spatial coordinates.
* Granule size has been reduced from one full ISS orbit (~1.2 GB) to four segments per orbit (~0.3 GB).
* Filename has been updated to include segment number and version number.
* Improved Geolocation.
* Added elevation from the SRTM digital elevation model for comparison.
* Modified the method to predict an optimum algorithm setting group per laser shot.
* Added additional land cover datasets related to phenology, urban infrastructure, and water persistence.
* Added selected_mode_flag dataset to root beam group using selected algorithm.
* Removed shots when the laser is not firing.
* Modified file name.

全球生态系统动态调查（GEDI）任务旨在描述生态系统结构及其动态，以极大地提升对地球碳循环和生物多样性的量化与理解。GEDI仪器生成对地球三维结构的高分辨率激光测距观测数据。GEDI仪器附着于国际空间站（ISS）上，在全球范围内，在北纬51.6°至南纬51.6°之间进行数据收集，其分辨率和采样密度为迄今为止任何轨道上的光探测与测距（lidar）仪器之最。每个GEDI版本2的数据单元覆盖了国际空间站轨道的四分之一，并包含地理参考元数据，以实现空间查询和子集化。

GEDI二级B级冠层覆盖和垂直剖面指标产品（GEDI02_B）的目的是从每个GEDI波形中提取生物物理指标。这些指标基于从L1B波形中推导出的方向性间隙概率剖面。提供的指标包括冠层覆盖、植物面积指数（PAI）、植物面积体积密度（PAVD）和叶高多样性（FHD）。GEDI02_B产品以HDF5格式提供，其空间分辨率为25米。

GEDI02_B数据产品包含96层，针对八个波束的地面横断面（或激光足迹，位于地表上）。提供的数据集包括精确的纬度、经度、高程、高度、冠层覆盖和垂直剖面指标。有关层的更多信息，请参阅GEDI二级B数据字典。

版本2的改进包括：
* 元数据已更新，包括空间坐标。
* 数据单元大小已从整个国际空间站轨道（约1.2 GB）减少到每个轨道的四个段（约0.3 GB）。
* 文件名已更新，包括段号和版本号。
* 改进了地理定位。
* 添加了来自SRTM数字高程模型的高程数据以供比较。
* 修改了预测每个激光射击的最优算法设置组的方法。
* 添加了与物候、城市基础设施和水持久性相关的额外土地覆盖数据集。
* 使用选择算法在根波束组中添加了selected_mode_flag数据集。
* 移除了激光未发射时的射击。
* 修改了文件名。