Google Earth Engine ——比Landsat更全的NDVI数据NOAA CDR AVHRR NDVI）1981-2019年0.05 degrees数据集

The NOAA Climate Data Record (CDR) of AVHRR Normalized Difference Vegetation Index (NDVI) contains gridded daily NDVI derived from the NOAA AVHRR Surface Reflectance product. It provides a measurement of surface vegetation coverage activity, gridded at a resolution of 0.05° and computed globally over land surfaces.

Known issues with this dataset include:

• TIMEOFDAY variable contains values that are too large by 1 day
• Latitude values are not correctly associated with the center of the grid cell, error is < 0.002 degrees
• Longitude values are not correctly associated with the center of the grid cell, error is < 0.02 degrees

NOAA气候数据记录（CDR）的AVHRR归一化植被指数（NDVI）包含从NOAA AVHRR表面反射产品中得到的网格化的每日NDVI。它提供了地表植被覆盖活动的测量，网格化的分辨率为0.05°，在全球范围内对陆地表面进行计算。

这个数据集的已知问题包括。

TIMEOFDAY变量包含的数值过大，超过1天。

纬度值与网格单元的中心没有正确关联，误差<0.002度

经度值与网格单元的中心没有正确关联，误差< 0.02度

Dataset Availability

1981-06-24T00:00:00 - 2019-05-16T00:00:00

Dataset Provider

​​NOAA​​

Collection Snippet

Copied

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​ee.ImageCollection("NOAA/CDR/AVHRR/NDVI/V4")​

​

Resolution

0.05 degrees

Bands Table

Name	Description	Min*	Max*	Units	Scale
NDVI	Normalized difference vegetation index	-9998	9998	0.0001
TIMEOFDAY	Hours since start of day	2400	hours	0.01
QA	Quality control bit flags
QA Bitmask	Bit 0: Unused 0: No 1: Yes Bit 1: Pixel is cloudy 0: No 1: Yes Bit 2: Pixel contains cloud shadow 0: No 1: Yes Bit 3: Pixel is over water 0: No 1: Yes Bit 4: Pixel is over sunglint 0: No 1: Yes Bit 5: Pixel is over dense dark vegetation 0: No 1: Yes Bit 6: Pixel is at night (high solar zenith) 0: No 1: Yes Bit 7: Channels 1-5 are valid 0: No 1: Yes Bit 8: Channel 1 value is invalid 0: No 1: Yes Bit 9: Channel 2 value is invalid 0: No 1: Yes Bit 10: Channel 3 value is invalid 0: No 1: Yes Bit 11: Channel 4 value is invalid 0: No 1: Yes Bit 12: Channel 5 value is invalid 0: No 1: Yes Bit 13: RHO3 value is invalid 0: No 1: Yes Bit 14: BRDF correction is invalid 0: No 1: Yes Bit 15: Polar flag, latitude over 60 degrees (land) or 50 degrees (ocean) 0: No 1: Yes

* = Values are estimated

数据属性：

Name	Type	Description
status	String	'provisional' or 'permanent'

 The NOAA CDR Program’s official distribution point for CDRs is NOAA’s National Climatic Data Center which provides sustained, open access and active data management of the CDR packages and related information in keeping with the United States’ open data policies and practices as described in the President's Memorandum on "Open Data Policy" and pursuant to the Executive Order of May 9, 2013, "Making Open and Machine Readable the New Default for Government Information". In line with these policies, the CDR data sets are nonproprietary, publicly available, and no restrictions are placed upon their use. For more information, see the ​​Fair Use of NOAA's CDR Data Sets, Algorithms and Documentation​​ pdf.

NOAA CDR计划的官方CDR分发点是NOAA的国家气候数据中心，该中心根据美国总统关于 "开放数据政策 "的备忘录和2013年5月9日的行政命令 "使开放和机器可读成为政府信息的新默认值"，对CDR包和相关信息提供持续、开放的访问和积极的数据管理。根据这些政策，CDR数据集是非专有的、可公开使用的，而且对其使用没有任何限制。欲了解更多信息，请参阅《公平使用NOAA的CDR数据集、算法和文件》pdf。 

数据引用：

Eric Vermote, Chris Justice, Ivan Csiszar, Jeff Eidenshink, Ranga Myneni, Frederic Baret, Ed Masuoka, Robert Wolfe, Martin Claverie and NOAA CDR Program (2014): NOAA Climate Data Record (CDR) of Normalized Difference Vegetation Index (NDVI), Version 4. [indicate subset used]. NOAA National Climatic Data Center. ​​doi:10.7289/V5PZ56R6​​

var dataset = ee.ImageCollection('NOAA/CDR/AVHRR/NDVI/V4')
                  .filter(ee.Filter.date('2018-05-01', '2018-06-01'));
var ndvi = dataset.select('NDVI');
var ndviVis = {
  min: -1000.0,
  max: 5000.0,
  palette: [
    'ffffff', 'ce7e45', 'fcd163', 'c6ca02', '22cc04', '99b718', '207401',
    '012e01'
  ],
};
Map.setCenter(7.71, 17.93, 2);
Map.addLayer(ndvi, ndviVis, 'NDVI');