Google Earth Engine ——LANDSAT 4系列归一化差异雪指数（NDSI）8天/32天/年际合成数据集

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 Snow Index is used to identify snow, based on its characteristically higher reflectance in the visible portion of the spectrum compared to the mid-IR. NDSI is computed using the Green and Mid-IR bands, and has a range of -1.0 to 1.0. See Riggs et al. (1994) 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。

归一化差异雪指数是用来识别雪的，基于其在光谱的可见部分比中红外更高的反射率的特点。NDSI使用绿色和中红外波段进行计算，范围为-1.0到1.0。详见Riggs等人（1994）。

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天的每8天的所有场景中创建。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_NDSI")

Bands Table

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.

代码：

var dataset = ee.ImageCollection('LANDSAT/LT04/C01/T1_ANNUAL_NDSI')
                  .filterDate('1989-01-01', '1992-12-31');
var colorized = dataset.select('NDSI');
var colorizedVis = {
  palette: ['000088', '0000FF', '8888FF', 'FFFFFF'],
};
Map.setCenter(6.746, 46.529, 6);
Map.addLayer(colorized, colorizedVis, 'Colorized');

var dataset = ee.ImageCollection('LANDSAT/LT04/C01/T1_32DAY_NDSI')
                  .filterDate('1989-01-01', '1992-12-31');
var colorized = dataset.select('NDSI');
var colorizedVis = {
  palette: ['000088', '0000FF', '8888FF', 'FFFFFF'],
};
Map.setCenter(6.746, 46.529, 6);
Map.addLayer(colorized, colorizedVis, 'Colorized');

var dataset = ee.ImageCollection('LANDSAT/LT04/C01/T1_8DAY_NDSI')
                  .filterDate('1989-01-01', '1992-12-31');
var colorized = dataset.select('NDSI');
var colorizedVis = {
  palette: ['000088', '0000FF', '8888FF', 'FFFFFF'],
};
Map.setCenter(6.746, 46.529, 6);
Map.addLayer(colorized, colorizedVis, 'Colorized');