CropWatch Input Data

Description

CropWatch utilizes various variables as input data, including

NDVI, LAI, and fAPAR data at a global scale, which are mostly MODIS products provided by NASA. Additionally, NDVI products from Chinese Fengyun-3 MERSI are also utilized.

Air temperature and photosynthetically active radiation (PAR) datasets are sourced from the National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2), 6-Hourly products. For further information about CFSv2, please refer to the CFS NOAA site. To enhance the characterization of light-use efficiency, this study integrated a high-resolution operational PAR dataset released in mid-2025 by the Cloud remote sensing, Atmosphere radiation and Renewal Energy (CARE) team in State Key Laboratory of Remote Sensing and Digital Earth, Aerospace Inforamtion Research Institute, Chinese Academy of Sciences. This advanced product provides an internal partitioning of radiation into Direct and Diffuse PAR components derived from geostationary satellite observations, allowing for a more nuanced analysis of crop canopy light absorption compared to global reanalysis products.

The rainfall product utilized in CropWatch is an integration of CFSv2 rainfall data and satellite-derived rainfall data from TRMM and GPM. It covers the land surface from 50 degrees south (50S) to 90 degrees north (90N) at a spatial resolution of 0.25 degrees.

Biomass is an indicator based on a model that integrates rainfall, air temperature, and PAR. Initially, the air temperature is used to derive a temperature-based constraint factor for biomass accumulation based on the Richardson model.  The potential biomass is calculated by multiplying the biomass derived from the Chikugo model and the Richardson temperature factor.

The Vegetation Health Index (VHI) product at a global scale is mainly provided by NOAA at a 4 km spatial resolution and weekly temporal resolution. The Vegetation Health Indices (VHI) are derived from the radiance observed by the Advanced Very High Resolution Radiometer (AVHRR) onboard afternoon polar-orbiting satellites, including the NOAA-7, 9, 11, 14, 16, 18, and 19, as well as VIIRS from the Soumi-NPP satellite.

High-resolution monitoring of crop mapping, irrigation detection, and cropping intensity assessment is performed using Sentinel-1, Sentinel-2, Landsat-8&9, as well as Chinese satellite images from Gaofen-1, Gaofen-6, and ZY-3, among others.

For further details, please refer to the attached file.

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