A 29-year time series of annual 300-metre resolution plant functional type maps for climate models

The existing CCI Medium Resolution land cover (MRLC) product delineates 22 primary and 15 secondary land cover classes at 300-meter resolution with global coverage and an annual time step extending from 1992 to the present. Previously, translation of the land cover classes into the plant functional types (PFTs) used by the Earth system and land surface models required the use of the CCI global cross-walking table that defines, for each land cover class, an invariant PFT fractional composition for every pixel of the class regardless of geographic location. Here, we present a new time series data product that circumvents the need for a cross-walking table. We use a quantitative, globally consistent method that fuses the 300-meter MRLC product with a suite of existing high-resolution datasets to develop spatially explicit annual maps of PFT fractional composition at 300 meters. The new PFT product exhibits intraclass spatial variability in PFT fractional cover at the 300-meter pixel level and is complementary to the MRLC maps since the derived PFT fractions maintain consistency with the original land cover class legend. This was only possible by ingesting several key 30m resolution global binary maps like the urban, the open water, the tree cover, and the tree height while controlling their compatibility thanks to the MRLC maps. This dataset is a significant step forward towards ready-to-use PFT descriptions for climate modelling at the pixel level. For each of the 29 years, 14 new maps are produced (one for each of 14 PFTs: bare soil, surface water, permanent snow and ice, built, managed grasses, natural grasses, and trees and shrubs each split into broadleaved evergreen, broadleaved deciduous, needleleaved evergreen, and needleleaved deciduous), with data values at 300-meter resolution indicating the percentage cover (0–100%) of the PFT in the given year. Based on land surface model simulations (ORCHIDEE and JULES models), we find significant differences in simulated carbon, water, and energy fluxes in some regions using the new PFT data product relative to the global cross-walking table applied to the MRLC maps. We additionally provide an updated user tool to assist in creating model-ready products to meet individual user needs (e.g., re-mapping, re-projection, PFT conversion, and spatial sub-setting).