The MOD17A3H V6 product provides information about annual Net Primary Productivity (NPP) at 500m pixel resolution. Annual NPP is derived from the sum of the 45 8-day Net Photosynthesis (PSN) products (MOD17A2H) from the given year. The PSN value is the difference of the GPP and the Maintenance Respiration (MR) (GPP-MR).
This is a NASA version of this product. Another version is produced by the Numerical Terradynamic Simulation Group (NTSG), University of Montana (UMT). The NTSG version corrects the problem with cloud-contaminated MODIS LAI-FPAR inputs to the MOD17 algorithm, but its resolution is 1km. It is ingested into Earth Engine as MODIS/055/MOD17A3.
For further details regarding the differences between the NTSG and NASA versions of this product, please consult this document .
MOD17A3H V6产品提供500米像素分辨率的年度净初级生产力（NPP）信息。年净初级生产力是由给定年份的45个8天净光合作用（PSN）产品（MOD17A2H）之和得出的。PSN值是GPP和维持呼吸（MR）之差（GPP-MR）。
这是该产品的NASA版本。另一个版本是由蒙大拿大学（UMT）的数字地球动力学模拟小组（NTSG）制作的。NTSG版本纠正了MOD17算法中被云层污染的MODIS LAI-FPAR输入的问题，但其分辨率为1公里。它作为MODIS/055/MOD17A3被录入地球引擎。
关于该产品的NTSG和NASA版本之间的差异的进一步细节，请参考该文件。
Dataset Availability
2000-01-01T00:00:00 - 2014-01-01T00:00:00
Dataset Provider
NASA LP DAAC at the USGS EROS Center
Collection Snippet
ee.ImageCollection("MODIS/006/MOD17A3H")
Resolution
500 meters
Bands Table
Name | Description | Min | Max | Units | Scale |
|---|---|---|---|---|---|
Npp | Net primary productivity | -3000 | 32700 | kg*C/m^2 | 0.0001 |
Npp_QC | Quality control bits | 0 | |||
Npp_QC Bitmask | Bit 0: MODLAND QC bits 0: Good quality1: Other qualityBit 1: Sensor 0: Terra1: AquaBit 2: Dead detector 0: Detectors apparently fine for up to 50% of channels 1, 21: Dead detectors caused >50% adjacent detector retrievalBits 3-4: Cloud state 0: Significant clouds NOT present (clear)1: Significant clouds WERE present2: Mixed cloud present on pixel3: Cloud state not defined, assumed clearBits 5-7: 5-level confidence quality score 0: Very best possible1: Good, very usable, but not the best2: Substandard due to geometry problems - use with caution3: Substandard due to other than geometry problems - use with caution4: Couldn't retrieve pixel (NOT PRODUCED AT ALL - non-terrestrial biome)7: Fill Value | ||||
- Bit 0: MODLAND QC bits
- 0: Good quality
- 1: Other quality
- Bit 1: Sensor
- 0: Terra
- 1: Aqua
- Bit 2: Dead detector
- 0: Detectors apparently fine for up to 50% of channels 1, 2
- 1: Dead detectors caused >50% adjacent detector retrieval
- Bits 3-4: Cloud state
- 0: Significant clouds NOT present (clear)
- 1: Significant clouds WERE present
- 2: Mixed cloud present on pixel
- 3: Cloud state not defined, assumed clear
- Bits 5-7: 5-level confidence quality score
- 0: Very best possible
- 1: Good, very usable, but not the best
- 2: Substandard due to geometry problems - use with caution
- 3: Substandard due to other than geometry problems - use with caution
- 4: Couldn't retrieve pixel (NOT PRODUCED AT ALL - non-terrestrial biome)
- 7: Fill Value
使用说明：
MODIS data and products acquired through the LP DAAC have no restrictions on subsequent use, sale, or redistribution.
数据引用：
LP DAAC - MOD17A3H
代码：
代码语言：javascript复制var dataset = ee.ImageCollection('MODIS/006/MOD17A3H')
.filter(ee.Filter.date('2014-01-01', '2015-05-01'));
var npp = dataset.select('Npp');
var nppVis = {
min: 0.0,
max: 19000.0,
palette: ['bbe029', '0a9501', '074b03'],
};
Map.setCenter(6.746, 46.529, 2);
Map.addLayer(npp, nppVis, 'NPP');
