三江源MODIS-NPP产品数据集（1985-2015）

该数据集包含了黄河源、长江源、澜沧江三个源区的最大值合成法生产的NPP产品数据。MOD13Q1、MOD17A2以及MOD17A2H遥感产品数据来自于NASA网站（http://modis.gsfc.nasa.gov/）。MOD13Q1产品的分辨率为250 m, 16 d合成产品。MOD17A2和MOD17A2H产品数据都是8 d合成产品, MOD17A2的分辨率为 1000 m, MOD17A2H的分辨率为500 m。最终合成的MODIS NPP产品的分辨率为1km。
下载的MOD13Q1、MOD17A2、MOD17A2H遥感数据产品, 格式为HDF, 该数据已经过大气校正、辐射校正、几何校正和去云等处理。1）MRT投影转换。将下载的数据产品进行格式和投影转换, 将HDF格式转换为TIFF格式, 将投影转换为UTM投影, 输出250 m分辨率的NDVI、250 m分辨率的EVI、1000 m和500 m两种分辨率的净光合PSNnet。2）MVC最大值合成。将与地面实测数据同期的NDVI、EVI、PSNnet采用最大值合成, 得到与实测数据对应的值。采用最大值合成法可以有效减少云、大气、太阳高度角等的影响。3)基于NASA-CASA模型生成NPP年值。

This dataset contains Net Primary Productivity (NPP) product data generated via the Maximum Value Composite (MVC) method for three source regions: the Yellow River Source, the Yangtze River Source, and the Lancang River Source. The remote sensing product data of MOD13Q1, MOD17A2 and MOD17A2H are sourced from the NASA website at http://modis.gsfc.nasa.gov/. MOD13Q1 is a 16-day composite product with a spatial resolution of 250 m. Both MOD17A2 and MOD17A2H are 8-day composite products: MOD17A2 has a spatial resolution of 1000 m, while MOD17A2H has a resolution of 500 m. The final synthesized MODIS NPP product has a spatial resolution of 1 km.

The downloaded remote sensing data products of MOD13Q1, MOD17A2 and MOD17A2H are in HDF format, and have undergone preprocessing steps including atmospheric correction, radiometric correction, geometric correction and cloud removal.
1) MRT Projection Conversion. The downloaded data products were converted in format and projection: the HDF format was converted to TIFF format, and the projection was transformed to UTM projection. The outputs include Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) with 250 m resolution, as well as net photosynthesis (PSNnet) with resolutions of 1000 m and 500 m respectively.
2) MVC Maximum Value Composite. The NDVI, EVI and PSNnet that match the timing of the ground-truth field data were processed via maximum value compositing to obtain values corresponding to the measured data. The MVC method can effectively reduce the impacts of clouds, atmosphere, solar altitude angle and other interfering factors.
3) Generation of annual NPP values based on the NASA-CASA model.

搜集汇总

背景与挑战

背景概述

该数据集是1985年至2015年间三江源地区（包括黄河源、长江源和澜沧江源区）的MODIS-NPP产品数据，基于NASA的MOD13Q1、MOD17A2和MOD17A2H遥感产品，通过最大值合成法和NASA-CASA模型处理生成，最终分辨率为1公里，用于植被生态研究。数据集具有长期时间序列和高空间分辨率特点，支持三江源国家公园及周边区域的生态监测与分析。