Google Earth Engine（GEE）—— 全球生态系统动态调查（GEDI）综合数据集（高程、森林覆盖、城市占比）

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, attached to the International Space Station (ISS), collects data globally between 51.6° N and 51.6° S latitudes at the highest resolution and densest sampling of the 3-dimensional structure of the Earth.

GEDI's Level 2A Geolocated Elevation and Height Metrics Product (GEDI02_A) is primarily composed of 100 Relative Height (RH) metrics, which collectively describe the waveform collected by GEDI.

The original GEDI02_A product is a table of point with a spatial resolution (average footprint) of 25 meters. The dataset LARSE/GEDI/GEDI02_A_002_MONTHLY is a raster version of the original GEDI02_A product. The raster images are organized as monthly composites of individual orbits in the corresponding month. Only root-level RH values and their associated quality flags and metadata are preserved as raster bands. Each GEDI02_A_002 raster has 136 bands.

See User Guide for more information.

全球生态系统动态调查（GEDI）任务的目的是描述生态系统的结构和动态，以便从根本上改善对地球碳循环和生物多样性的量化和理解。附属于国际空间站（ISS）的GEDI仪器在全球范围内收集北纬51.6°和南纬51.6°之间的数据，对地球的三维结构进行最高分辨率和最密集的采样。

GEDI的2A级地理位置海拔和高度指标产品（GEDI02_A）主要由100个相对高度（RH）指标组成，它们共同描述了GEDI收集的波形。

原始的GEDI02_A产品是一个点的表格，空间分辨率（平均足迹）为25米。数据集LARSE/GEDI/GEDI02_A_002_MONTHLY是原始GEDI02_A产品的栅格版本。光栅图像被组织为相应月份的单个轨道的月度合成。只有根级相对湿度值及其相关的质量标志和元数据被保留为栅格带。每个GEDI02_A_002栅格有136个波段。

GEDI L2A Canopy Top Height (Version 2)

Dataset Availability

2019-03-25T00:00:00Z - 2021-09-01T00:00:00

Dataset Provider

NASA GEDI mission, accessed through the USGS LP DAAC Rasterization: Google and USFS Laboratory for Applications of Remote Sensing in Ecology (LARSE)

Earth Engine Snippet

ee.ImageCollection("LARSE/GEDI/GEDI02_A_002_MONTHLY") open_in_new

波段：

Resolution 25 meters

Bands

• 3X - ADF CHU solution unavailable (ST-2)
• 4X - Platform attitude
• 5X - Poor solution (filter covariance large)
• 6X - Data outage (platform attitude gap also)
• 7X - ST 1+2 unavailable (similar boresight FOV)
• 8X - ST 1+2+3 unavailable
• 9X - ST 1+2+3 and ISS unavailable
• X1 - Maneuver
• X2 - GPS data gap
• X3 - ST blinding
• X4 - Other
• X5 - GPS receiver clock drift
• X6 - Maneuver & GPS receiver clock drift
• X7 - GPS data gap & GPS receiver clock drift
• X8 - ST blinding & GPS receiver clock drift
• X9 - Other & GPS receiver clock drift

delta_time Time delta since Jan 1 00:00 2018 digital_elevation_model TanDEM-X elevation at GEDI footprint location digital_elevation_model_srtm STRM elevation at GEDI footprint location elev_highestreturn Elevation of highest detected return relative to reference ellipsoid elev_lowestmode Elevation of center of lowest mode relative to reference ellipsoid elevation_bias_flag Elevations potentially affected by 4bin (~60 cm) ranging error landsat_treecover Tree cover in the year 2010, defined as canopy closure for all vegetation taller than 5 m in height as a percentage per output grid cell landsat_water_persistence Percent UMD GLAD Landsat observations with classified surface water lat_highestreturn Latitude of highest detected return leaf_off_doy GEDI 1 km EASE 2.0 grid leaf-off start day-of-year leaf_off_flag GEDI 1 km EASE 2.0 grid flag leaf_on_cycle Flag that indicates the vegetation growing cycle for leaf-on observations leaf_on_doy GEDI 1 km EASE 2.0 grid leaf-on start day-of-year lon_highestreturn Longitude of highest detected return modis_nonvegetated Percent non-vegetated from MODIS MOD44B V6 data modis_nonvegetated_sd Percent non-vegetated standard deviation from MODIS MOD44B V6 data modis_treecover Percent tree cover from MODIS MOD44B V6 data modis_treecover_sd Percent tree cover standard deviation from MODIS MOD44B V6 data num_detectedmodes Number of detected modes in rxwaveform pft_class GEDI 1 km EASE 2.0 grid Plant Functional Type (PFT) quality_flag Flag indicating likely invalid waveform (1=valid, 0=invalid) region_class GEDI 1 km EASE 2.0 grid world continental regions selected_algorithm Identifier of algorithm selected as identifying the lowest non-noise mode selected_mode Identifier of mode selected as lowest non-noise mode selected_mode_flag Flag indicating status of selected_mode sensitivity Maxmimum canopy cover that can be penetrated shot_number Shot number, a unique identifier. This field is truncated on some images that are being reprocessed to properly show it (as of March 2022). This field has the format of OOOOOBBRRGNNNNNNNN, where:

• OOOOO: Orbit number
• BB: Beam number
• RR: Reserved for future use
• G: Sub-orbit granule number
• NNNNNNNN: Shot index

solar_azimuth Solar azimuth solar_elevation Solar elevation surface_flag Indicates elev_lowestmode is within 300 m of DEM or MSS urban_focal_window_size The focal window size used to calculate urban_proportion urban_proportion The percentage proportion of land area within a focal area surrounding each shot that is urban land cover. rh0 Relative height metrics at 0% rh1 Relative height metrics at 1% rh2 Relative height metrics at 2% rh3 Relative height metrics at 3% rh4 Relative height metrics at 4% rh5 Relative height metrics at 5% rh6 Relative height metrics at 6% rh7 Relative height metrics at 7% rh8 Relative height metrics at 8% rh9 Relative height metrics at 9% rh10 Relative height metrics at 10% rh11 Relative height metrics at 11% rh12 Relative height metrics at 12% rh13 Relative height metrics at 13% rh14 Relative height metrics at 14% rh15 Relative height metrics at 15% rh16 Relative height metrics at 16% rh17 Relative height metrics at 17% rh18 Relative height metrics at 18% rh19 Relative height metrics at 19% rh20 Relative height metrics at 20% rh21 Relative height metrics at 21% rh22 Relative height metrics at 22% rh23 Relative height metrics at 23% rh24 Relative height metrics at 24% rh25 Relative height metrics at 25% rh26 Relative height metrics at 26% rh27 Relative height metrics at 27% rh28 Relative height metrics at 28% rh29 Relative height metrics at 29% rh30 Relative height metrics at 30% rh31 Relative height metrics at 31% rh32 Relative height metrics at 32% rh33 Relative height metrics at 33% rh34 Relative height metrics at 34% rh35 Relative height metrics at 35% rh36 Relative height metrics at 36% rh37 Relative height metrics at 37% rh38 Relative height metrics at 38% rh39 Relative height metrics at 39% rh40 Relative height metrics at 40% rh41 Relative height metrics at 41% rh42 Relative height metrics at 42% rh43 Relative height metrics at 43% rh44 Relative height metrics at 44% rh45 Relative height metrics at 45% rh46 Relative height metrics at 46% rh47 Relative height metrics at 47% rh48 Relative height metrics at 48% rh49 Relative height metrics at 49% rh50 Relative height metrics at 50% rh51 Relative height metrics at 51% rh52 Relative height metrics at 52% rh53 Relative height metrics at 53% rh54 Relative height metrics at 54% rh55 Relative height metrics at 55% rh56 Relative height metrics at 56% rh57 Relative height metrics at 57% rh58 Relative height metrics at 58% rh59 Relative height metrics at 59% rh60 Relative height metrics at 60% rh61 Relative height metrics at 61% rh62 Relative height metrics at 62% rh63 Relative height metrics at 63% rh64 Relative height metrics at 64% rh65 Relative height metrics at 65% rh66 Relative height metrics at 66% rh67 Relative height metrics at 67% rh68 Relative height metrics at 68% rh69 Relative height metrics at 69% rh70 Relative height metrics at 70% rh71 Relative height metrics at 71% rh72 Relative height metrics at 72% rh73 Relative height metrics at 73% rh74 Relative height metrics at 74% rh75 Relative height metrics at 75% rh76 Relative height metrics at 76% rh77 Relative height metrics at 77% rh78 Relative height metrics at 78% rh79 Relative height metrics at 79% rh80 Relative height metrics at 80% rh81 Relative height metrics at 81% rh82 Relative height metrics at 82% rh83 Relative height metrics at 83% rh84 Relative height metrics at 84% rh85 Relative height metrics at 85% rh86 Relative height metrics at 86% rh87 Relative height metrics at 87% rh88 Relative height metrics at 88% rh89 Relative height metrics at 89% rh90 Relative height metrics at 90% rh91 Relative height metrics at 91% rh92 Relative height metrics at 92% rh93 Relative height metrics at 93% rh94 Relative height metrics at 94% rh95 Relative height metrics at 95% rh96 Relative height metrics at 96% rh97 Relative height metrics at 97% rh98 Relative height metrics at 98% rh99 Relative height metrics at 99% rh100 Relative height metrics at 100%

代码：

var qualityMask = function(im) {
  return im.updateMask(im.select('quality_flag').eq(1))
      .updateMask(im.select('degrade_flag').eq(0));
};
var dataset = ee.ImageCollection('LARSE/GEDI/GEDI02_A_002_MONTHLY')
                  .map(qualityMask)
                  .select('rh98');

var gediVis = {
  min: 1,
  max: 60,
  palette: 'darkred,red,orange,green,darkgreen',
};
Map.setCenter(-74.803466, -9.342209, 10);
Map.addLayer(dataset, gediVis, 'rh98');