Results from time-series analysis of Landsat images in characterizing global forest extent and change.
The 'first' and 'last' bands are reference multispectral imagery from the first and last available years for Landsat spectral bands 3, 4, 5, and 7. Reference composite imagery represents median observations from a set of quality-assessed growing-season observations for each of these bands.
Please see the User Notes for this Version 1.0, as well as the associated journal article: Hansen, Potapov, Moore, Hancher et al. “High-resolution global maps of 21st-century forest cover change.” Science 342.6160 (2013): 850-853.
Note that updated versions of this data are available. The newest version, Version 1.8 (produced with data through 2020), is available as UMD/hansen/global_forest_change_2020_v1_8.
Landsat图像在描述全球森林范围和变化方面的时间序列分析结果。
第一个 "和 "最后一个 "波段是Landsat光谱波段3、4、5和7的第一个和最后一个可用年份的参考多光谱图像。参考综合图像代表了这些波段中每个波段的一组质量评估过的生长季节观测值的中位数。
请参见该1.0版的用户说明以及相关的期刊文章。Hansen, Potapov, Moore, Hancher等人，"21世纪森林覆盖变化的高分辨率全球地图"。科学》342.6160（2013）：850-853。
请注意，该数据的更新版本是可用的。最新的版本是1.8版（用到2020年的数据制作），可在UMD/hansen/global_forest_change_2020_v1_8中找到。
Dataset Availability
2000-01-01T00:00:00 - 2014-01-01T00:00:00
Dataset Provider
Collection Snippet
Copied
ee.Image("UMD/hansen/global_forest_change_2014")
Resolution
30.92 meters
Bands Table
| Name | Description | Min | Max | Units | Wavelength |
| treecover2000 | Tree canopy cover for year 2000, defined as canopy closure for all vegetation taller than 5m in height. | 0 | 100 | % | |
| loss | Forest loss during the study period, defined as a stand-replacement disturbance (a change from a forest to non-forest state). | ||||
| loss Bitmask |
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| gain | Forest gain during the period 2000–2012, defined as the inverse of loss (a non-forest to forest change entirely within the study period). Note that this has not been updated in subsequent versions. | ||||
| gain Bitmask |
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| first_b30 | Landsat 7 band 3 (red) cloud-free image composite. Reference multispectral imagery from the first available year, typically 2000. | 0.63-0.69μm | |||
| first_b40 | Landsat 7 band 4 (NIR) cloud-free image composite. Reference multispectral imagery from the first available year, typically 2000. | 0.77-0.90μm | |||
| first_b50 | Landsat 7 band 5 (SWIR) cloud-free image composite. Reference multispectral imagery from the first available year, typically 2000. | 1.55-1.75μm | |||
| first_b70 | Landsat 7 band 7 (SWIR) cloud-free image composite. Reference multispectral imagery from the first available year, typically 2000. | 2.09-2.35μm | |||
| last_b30 | Landsat 7 band 3 (red) cloud-free image composite. Reference multispectral imagery from the last available year, typically the last year of the study period. | 0.63-0.69μm | |||
| last_b40 | Landsat 7 band 4 (NIR) cloud-free image composite. Reference multispectral imagery from the last available year, typically the last year of the study period. | 0.77-0.90μm | |||
| last_b50 | Landsat 7 band 5 (SWIR) cloud-free image composite. Reference multispectral imagery from the last available year, typically the last year of the study period. | 1.55-1.75μm | |||
| last_b70 | Landsat 7 band 7 (SWIR) cloud-free image composite. Reference multispectral imagery from the last available year, typically the last year of the study period. | 2.09-2.35μm | |||
| datamask | Three values representing areas of no data, mapped land surface, and permanent water bodies. | ||||
| datamask Bitmask |
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| lossyear | Year of gross forest cover loss event. A disaggregation of total forest loss to annual time scales. Encoded as either 0 (no loss) or else a value in the range 1–12, representing loss detected primarily in the year 2001–2012, respectively. | 0 | 12 | ||
引用：
Hansen, M. C., P. V. Potapov, R. Moore, M. Hancher, S. A. Turubanova, A. Tyukavina, D. Thau, S. V. Stehman, S. J. Goetz, T. R. Loveland, A. Kommareddy, A. Egorov, L. Chini, C. O. Justice, and J. R. G. Townshend.
- “High-Resolution Global Maps of 21st-Century Forest Cover Change.” Science 342 (15 November): 850–53. Data available on-line at: https://earthenginepartners.appspot.com/science-2013-global-forest.
代码：
var dataset = ee.Image("UMD/hansen/global_forest_change_2014"); var visualization = { bands: ['treecover2000'], min: 0.0, max: 100.0, palette: [ "3d3d3d","080a02","080a02","080a02","106e12","37a930", "03ff17", ] }; Map.setCenter(-60.5, -20.0, 2); Map.addLayer(dataset, visualization, "Tree Canopy Cover");
