Global Snow-free Leaf Area Index Dataset for Earth System Modeling – Year 1992

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.