These Landsat 4 TM 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 8-day period beginning from the first day of the year and continuing to the 360th day of the year. The last composite of the year, beginning on day 361, will overlap the first composite of the following year by 3 days. All the images from each 8-day period are included in the composite, with the most recent pixel as the composite value.

这些Landsat 4 TM合成物是由L1T级正射场景制作的，使用计算的大气层顶部（TOA）反射率。关于TOA计算的细节，见Chander等人（2009）。

从2017年5月1日起，美国地质调查局不再生产预收集的Landsat，因此这个收集已经完成。请切换到基于集合1的数据集。更多信息请参见本文档页面。

归一化差异水指数（NDWI）对植被冠层的液态水含量变化很敏感。它是由近红外波段和第二个红外波段得出的，如果有的话，≈1.24μm，否则就是最接近的红外波段。它的数值范围为-1.0到1.0。详见Gao（1996）。

这些合成物是从一年中的第一天开始，一直到一年中的第360天，每8天的所有场景中创建的。这一年的最后一次合成，从第361天开始，将与下一年的第一次合成重叠3天。每个8天期间的所有图像都包括在合成中，以最近的像素作为合成值。

Dataset Availability

- 1993-12-19T00:00:00

Dataset Provider

​​USGS​​

Collection Snippet

​​ee.ImageCollection("LANDSAT/LT4_L1T_8DAY_NDWI")​​

Bands Table

Name

Description

Resolution

NDWI

Normalized Difference Water Index

30 meters

使用说明：

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数据集是联邦创建的数据，因此属于公共领域，可以在没有版权限制的情况下使用、转让或复制。

对美国地质调查局作为数据来源的鸣谢或信用，应包括一行文字的引用，如下面的例子。

(产品、图像、照片或数据集名称）由美国地质调查局提供。

例子。Landsat-7图像由美国地质调查局提供

请参阅美国地质调查局视觉识别系统指南，了解有关美国地质调查局产品的正确引用和鸣谢的进一步细节。

代码：

var dataset = ee.ImageCollection('LANDSAT/LT04/C01/T1_ANNUAL_NDWI')
                  .filterDate('1989-01-01', '1992-12-31');
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/LT04/C01/T1_8DAY_NDWI')
                  .filterDate('1989-01-01', '1992-12-31');
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/LT04/C01/T1_32DAY_NDWI')
                  .filterDate('1989-01-01', '1992-12-31');
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');

Google Earth Engine ——LANDSAT 4系列归一化差异水指数（NDWI）——8天/32天/年际合成数据集_数据集