MODIS Collection 6.1 Sinusoidal Tiles 8-daily gap-filled Gross Primary Production

<strong>Abstract:</strong> MODIS Collection 6.1 8-day gap-filled Gross Primary Production (GPP) and Net Photosynthesis data on the MODIS sinusoidal grid provided by LPDAAC: https://doi.org/10.5067/MODIS/MOD17A2HGF.061 (last accessed: 2024-05-07) are read together with their bit-encoded quality information from the HDF-files. The quality information is decoded and provided in form of separate flag layers in addition to the GPP and Net Photosynthesis data for each tile of the MODIS sinusoidal grid in netCDF file format (see https://www.cen.uni-hamburg.de/en/icdc/data/land/modis-primaryproduction.html). For each tile, latitude and longitude information of the center of each 500 m x 500 m pixel is provided in a separate netCDF file.

<strong>TableOfContents:</strong> gross_primary_production (gpp); net_photosynthesis; gpp_quality_flag; gpp_confidence_flag

<strong>Technical Info:</strong> dimension: 2400 columns x 2400 rows x unlimited; temporalExtent_startDate: 2000-02-18; temporalExtent_endDate: 2023-12-31; temporalResolution: 8-daily; spatialResolution: 500; spatialResolutionUnit: meter; horizontalResolutionXdirection: 500; horizontalResolutionXdirectionUnit: meter; horizontalResolutionYdirection: 500; horizontalResolutionYdirectionUnit: meter; verticalResolution: none; verticalResolutionUnit: none; verticalStart: none; verticalEnd: none; instrumentName: MODerate Resolution Spectroradiometer (MODIS); instrumentType: visible_to_infrared_spectroradiometer; instrumentLocation: Earth Observation Satellite (EOS) Terra; instrumentProvider: NOAA/NASA 

<strong>Methods:</strong> [1] Running, S. W., and M. Zhao, Users Guide Daily GPP and Annual NPP (MOD17A2H/A3H) and Year-end Gap-Filled (MOD17A2HGF/A3HGF) Products NASA Earth Observing System MODIS Land Algorithm, (For Collection 6), Version 4.0, January 2, 2019; [2] Running, S. W., R. R. Nemani, F. A. Heinsch, M. Zhao, M. Reeves, and H. Hashimoto, A continuous satellite-derived measure of global terrestrial primary production. Bioscience, 54(6), 547-560, 2004; [3] Running, S. W., A measurable planetary boundary layer for the biosphere. Science, 337(6101), 1458-1459, 2012; [4] Zhao, M., F. A. Heinsch, R. R. Nemani, and S. W. Running, Improvements of the MODIS terrestrial gross and net primary production global data set. Remote Sensing of Environment, 95(2), 164-176, 2005

<strong>Units:</strong> kg C m-2; kg C m-2;1; 1

<strong>geoLocations:</strong> westBoundLongitude: depends on tile; eastBoundLongitude: depends on tile; southBoundLatitude: depends on tile; northBoundLatitude: depends on tile; geoLocationPlace: global on land, see: https://modis-land.gsfc.nasa.gov/MODLAND_grid.html

<strong>Size: </strong>(files are packed into one zip-archive per year)

2000-2021 and 2023: each zip file is about 47.5 Gbyte large; each single file approximately 34.5 Mbytes, for the number of tiles see https://modis-land.gsfc.nasa.gov/MODLAND_grid.html
Data of the year 2022 are not published because data provided by LPDAAC seemed to be not reliable

<strong>Format:</strong> netCDF

<strong>DataSources:</strong>

Original data on sinusoidal grid tiles in hdf-format: https://doi.org/10.5067/MODIS/MOD17A2HGF.061 (last accessed: 2024-05-07), see also https://lpdaac.usgs.gov/products/mod17a2hgfv061/ (last accessed: 2024-05-07)

<strong>Contact:</strong> stefan.kern (at) uni-hamburg.de

<strong>Web page:</strong> https://www.cen.uni-hamburg.de/en/icdc/data/land/modis-primaryproduction.html (last accessed: 2024-05-10)

**摘要：** 由陆地过程分布式活动档案中心（Land Process Distributed Active Archive Center, LPDAAC）提供的MODIS集合6.1（Collection 6.1）8天间隙填充总初级生产量（Gross Primary Production, GPP）与净光合速率数据，基于MODIS正弦格网，其原始数据存储于HDF文件中，将与比特编码的质量信息一同读取。质量信息经解码后，除了为MODIS正弦格网每个瓦片提供的GPP与净光合速率数据外，还以独立的标志图层形式一并输出，数据格式为netCDF（详见https://www.cen.uni-hamburg.de/en/icdc/data/land/modis-primaryproduction.html）。针对每个瓦片，每个500米×500米像素中心点的经纬度信息会存储于独立的netCDF文件中。

**目录：** 总初级生产量（gross_primary_production, gpp）；净光合速率（net_photosynthesis）；GPP质量标志位（gpp_quality_flag）；GPP置信度标志位（gpp_confidence_flag）

**技术信息：** 维度：2400列×2400行×无限制；时间范围起始日期：2000-02-18；时间范围结束日期：2023-12-31；时间分辨率：8天；空间分辨率：500；空间分辨率单位：米；X方向水平分辨率：500；X方向水平分辨率单位：米；Y方向水平分辨率：500；Y方向水平分辨率单位：米；垂直分辨率：无；垂直分辨率单位：无；垂直起始值：无；垂直结束值：无；仪器名称：中分辨率成像光谱仪（MODerate Resolution Spectroradiometer, MODIS）；仪器类型：可见光至红外光谱辐射计；搭载平台：地球观测卫星（Earth Observation Satellite, EOS）Terra；数据提供方：美国国家海洋和大气管理局/美国国家航空航天局（NOAA/NASA）

**研究方法：** [1] Running, S. W. 与 Zhao, M.，《NASA地球观测系统MODIS陆地算法每日GPP与年度NPP（MOD17A2H/A3H）及年末间隙填充（MOD17A2HGF/A3HGF）产品用户指南（集合6版）》，4.0版本，2019年1月2日；[2] Running, S. W.、Nemani, R. R.、Heinsch, F. A.、Zhao, M.、Reeves, M. 与 Hashimoto, H.，一种基于卫星的全球陆地初级生产力连续测量方法，《生物科学》，54(6)，547-560，2004年；[3] Running, S. W.，生物圈可量化的行星边界层，《科学》，337(6101)，1458-1459，2012年；[4] Zhao, M.、Heinsch, F. A.、Nemani, R. R. 与 Running, S. W.，MODIS陆地总与净初级生产力全球数据集的改进，《环境遥感》，95(2)，164-176，2005年

**单位：** 千克碳每平方米（kg C m⁻²）；千克碳每平方米（kg C m⁻²）；无量纲；无量纲

**地理覆盖范围：** 西边界经度：随瓦片而异；东边界经度：随瓦片而异；南边界纬度：随瓦片而异；北边界纬度：随瓦片而异；地理覆盖区域：全球陆地区域，详见：https://modis-land.gsfc.nasa.gov/MODLAND_grid.html

**数据大小：** （数据按年份打包为单个zip压缩归档文件）2000年至2021年及2023年：每个zip归档文件大小约为47.5吉字节；单个文件大小约为34.5兆字节，瓦片数量详见https://modis-land.gsfc.nasa.gov/MODLAND_grid.html。2022年数据未发布，原因是陆地过程分布式活动档案中心（LPDAAC）提供的该年份数据可靠性不足。

**数据格式：** netCDF

**数据源：** 正弦格网瓦片格式的原始HDF数据：https://doi.org/10.5067/MODIS/MOD17A2HGF.061（最后访问时间：2024年5月7日），另可参考https://lpdaac.usgs.gov/products/mod17a2hgfv061/（最后访问时间：2024年5月7日）

**联系方式：** stefan.kern (at) uni-hamburg.de

**数据集官网：** https://www.cen.uni-hamburg.de/en/icdc/data/land/modis-primaryproduction.html（最后访问时间：2024年5月10日）