Changes to this version largely affect model inputs and ancillary files rather than changes to the internal model structure or code. Note that Version 4 is slightly better than Version 3 in RMSE terms, with improvement generally larger for drier sites. Specific changes include:
- The carbon model biome properties lookup table (BPLUT) has been calibrated using an augmented FLUXNET global tower site record which includes more calibration sites (335 sites compared to 228 sites for V3), expanded tower data records extending to at least 2015, and the addition of new tower sites representing more land cover types.
- Revised Level-4 carbon global model calibration and SOC initialization using an extended (2000-2017) MODIS fPAR (V006) record and the latest SMAP Nature Run (NRv7.2) climate data records.
- Implemented minor changes to spatial weighting of calibration tower sites within a model grid cell and reduced the outlier influence on model response curve fitting.
For the full major and minor version history, go to https://nsidc.org/data/smap/data_versions.