Google Earth Engine ——LANDSAT8系列歸一化差異水指數NDWI資料集

These Landsat 8 composites are made from Level L1T orthorectified scenes, using the computed top-of-atmosphere (TOA) reflectance. See Chander et al. (2009) for details on the TOA computation.

As of May 1, 2017, the USGS is no longer producing Pre-Collection Landsat, and therefore this collection is complete. Please switch to a Collection 1-based dataset. See this documentation page for more information.

The Normalized Difference Water Index (NDWI) is sensitive to changes in liquid water content of vegetation canopies. It is derived from the Near-IR band and a second IR band, ≈1.24μm when available and the nearest available IR band otherwise. It ranges in value from -1.0 to 1.0. See Gao (1996) for details.

These composites are created from all the scenes in each 32-day period beginning from the first day of the year and continuing to the 352nd day of the year. The last composite of the year, beginning on day 353, will overlap the first composite of the following year by 20 days. All the images from each 32-day period are included in the composite, with the most recent pixel as the composite value.

這些Landsat 8的合成物是由L1T級正射場景制作的，使用計算的大氣層頂部（TOA）反射率。關于TOA計算的細節，見Chander等人（2009）。

從2017年5月1日起，美國地質調查局不再生産預收集的Landsat，是以這個收集已經完成。請切換到基于集合1的資料集。更多資訊請參見本文檔頁面。

歸一化差異水指數（NDWI）對植被冠層的液态水含量變化很敏感。它是由近紅外波段和第二個紅外波段得出的，如果有的話，≈1.24μm，否則就是最接近的紅外波段。它的數值範圍在-1.0到1.0之間。詳見Gao（1996）。

這些合成物是由每年的第一天開始到第352天的每32天的所有場景建立的。這一年的最後一次合成，從第353天開始，将與下一年的第一次合成重疊20天。每個32天期間的所有圖像都包括在合成中，以最近的像素作為合成值。

使用說明：

Landsat datasets are federally created data and therefore reside in the public domain and may be used, transferred, or reproduced without copyright restriction.

Acknowledgement or credit of the USGS as data source should be provided by including a line of text citation such as the example shown below.

(Product, Image, Photograph, or Dataset Name) courtesy of the U.S. Geological Survey

Example: Landsat-7 image courtesy of the U.S. Geological Survey

See the USGS Visual Identity System Guidance for further details on proper citation and acknowledgement of USGS products.

Landsat資料集是聯邦建立的資料，是以屬于公共領域，可以在沒有版權限制的情況下使用、轉讓或複制。

對美國地質調查局作為資料來源的确認或信用，應通過包括一行文字引用來提供，如下面的例子。

(産品、圖像、照片或資料集名稱）由美國地質調查局提供。

例子。Landsat-7圖像由美國地質調查局提供

請參閱美國地質調查局視覺識别系統指南，了解有關美國地質調查局産品的正确引用和鳴謝的進一步細節。

代碼：

var dataset = ee.ImageCollection('LANDSAT/LC08/C01/T1_8DAY_NDWI')
                  .filterDate('2017-01-01', '2017-12-31');
var colorized = dataset.select('NDWI');
var colorizedVis = {
  min: 0.0,
  max: 1.0,
  palette: ['0000ff', '00ffff', 'ffff00', 'ff0000', 'ffffff'],
};
Map.setCenter(6.746, 46.529, 6);
Map.addLayer(colorized, colorizedVis, 'Colorized');
           

var dataset = ee.ImageCollection('LANDSAT/LE07/C01/T1_32DAY_NDWI')
                  .filterDate('1999-01-01', '2002-12-31');
var colorized = dataset.select('NDWI');
var colorizedVis = {
  min: 0.0,
  max: 1.0,
  palette: ['0000ff', '00ffff', 'ffff00', 'ff0000', 'ffffff'],
};
Map.setCenter(6.746, 46.529, 6);
Map.addLayer(colorized, colorizedVis, 'Colorized');
           

var dataset = ee.ImageCollection('LANDSAT/LE07/C01/T1_ANNUAL_NDWI')
                  .filterDate('1999-01-01', '2002-12-31');
var colorized = dataset.select('NDWI');
var colorizedVis = {
  min: 0.0,
  max: 1.0,
  palette: ['0000ff', '00ffff', 'ffff00', 'ff0000', 'ffffff'],
};
Map.setCenter(6.746, 46.529, 6);
Map.addLayer(colorized, colorizedVis, 'Colorized');