Global Snow-free Leaf Area Index Dataset for Earth System Modeling – Year 1994

The snow-free Leaf Area Index (LAI) dataset is a global monthly LAI product developed for land surface and earth system modeling. It covers the period from 1985 to 2020 at 500 m spatial resolution and aims to constrain the underestimation of LAI in snow-covered regions caused by snow contamination. The dataset was generated by integrating reprocessed MODIS Collection 6.1 LAI and GIMMS LAI4g products with plant functional type (PFT) information. Snow-affected areas were identified using satellite-based observations, and LAI was corrected at the PFT level using leaf lifespan constraints derived from the TRY plant trait database. The resulting snow-free LAI better represents the phenology of evergreen vegetation and is intended to support studies of vegetation–snow interactions, land surface processes, and earth system modeling. The dataset provides monthly LAI and SAI at 500 m spatial resolution globally, distributed as NetCDF-4 format files. Each file covers a 5° × 5° geographic region containing 1200 × 1200 pixels (0.00416667° or 15 arc-seconds per pixel) in the WGS84 coordinate system. The global land surface is divided into 1,447 regional tiles, with files named according to the convention RG_LatN_LonW_LatS_LonE.LSAI500m.YYYY.nc, where the latitude and longitude bounds define the tile coverage and YYYY indicates the year. Each file contains four primary data variables: MONTHLY_LC_LAI and MONTHLY_LC_SAI representing 500 m grid LAI and SAI values with dimensions (12 months × 1200 lat × 1200 lon), and MONTHLY_PFT_LAI and MONTHLY_PFT_SAI providing PFT LAI and SAI values with dimensions (12 months × 16 PFTs × 1200 lat × 1200 lon). Grid LAI (SAI) and PFT LAI (SAI) are both available for user selection according to research demands. The grid LAI (SAI) is calculated as the area-weighted average of PFT LAI (SAI). All LAI and SAI values are stored as unsigned byte integers with a scale factor of 0.1 and units of m2/m2, requiring multiplication by 0.1 to obtain physical values. The 16 plant functional types include various tree, shrub, grass, and crop categories ranging from tropical to boreal biomes. Coordinate variables (lat, lon, pft, mon) are included with appropriate metadata.无雪叶面积指数（Leaf Area Index, LAI）数据集是一款面向地表与地球系统建模开发的全球月度LAI产品，时间覆盖1985年至2020年，空间分辨率为500米，旨在校正积雪污染导致的积雪覆盖区域LAI低估问题。 该数据集通过将经再处理的MODIS Collection 6.1 LAI与GIMMS LAI4g产品，结合植物功能型（Plant Functional Type, PFT）信息融合生成。研究人员通过卫星观测识别受积雪影响的区域，并基于TRY植物性状数据库提取的叶片寿命约束条件，在PFT层面完成LAI校正。最终得到的无雪LAI能够更精准地反映常绿植被的物候特征，可为植被-积雪相互作用、地表过程及地球系统建模等相关研究提供支撑。 本数据集提供全球范围内500米空间分辨率的月度LAI与雪面积指数（Snow Area Index, SAI）数据，以NetCDF-4格式文件进行分发。单个文件覆盖5°×5°的地理区域，在WGS84坐标系下包含1200×1200个像素（单个像素对应0.00416667°，即15角秒）。全球陆地表面被划分为1447个区域瓦片，文件命名遵循RG_LatN_LonW_LatS_LonE.LSAI500m.YYYY.nc规范，其中经纬度边界定义瓦片的覆盖范围，YYYY代表对应年份。 每个文件包含四个核心数据变量：MONTHLY_LC_LAI与MONTHLY_LC_SAI代表500米网格LAI和SAI值，维度为(12个月 × 1200纬度 × 1200经度)；MONTHLY_PFT_LAI与MONTHLY_PFT_SAI则提供PFT层面的LAI和SAI值，维度为(12个月 × 16个PFT类型 × 1200纬度 × 1200经度)。用户可根据研究需求选择网格LAI(SAI)或PFT LAI(SAI)，其中网格LAI(SAI)通过PFT LAI(SAI)的面积加权平均计算得到。 所有LAI和SAI值均以无符号字节整数格式存储，缩放因子为0.1，单位为m²/m²，需将数值乘以0.1方可得到实际物理值。16种植物功能型涵盖从热带至寒带生物群系的各类乔木、灌木、草本与作物类别。文件中还包含坐标变量（lat、lon、pft、mon）及配套元数据。