Development of long‐term spatiotemporal continuous NDVI products for alpine grassland from 1982 to 2020 in the Qinghai–Tibet Plateau, China

• Published in: Grassland research (Online) Vol. 3; no. 2; pp. 100 - 112
• Main Authors: Yang, Xiali, Huang, Xiaodong, Ma, Ying, Li, Yuxin, Feng, Qisheng, Liang, Tiangang
• Format: Journal Article
• Language: English
• Published: Lanzhou John Wiley & Sons, Inc 01.06.2024; Wiley
• Subjects: Accuracy; Algorithms; alpine grassland; Climate change; Datasets; Ecosystems; Grasslands; Landsat satellites; long term; Machine learning; MODIS; Monitoring; NDVI; Neural networks; Normalized difference vegetative index; Remote sensing; Root-mean-square errors; Sensors; Spatial discrimination; Spatial resolution; Spectroradiometers; Support vector machines; Terrestrial ecosystems; Trends; Vegetation; Vegetation changes; Tibetan Plateau; China
• ISSN: 2097-051X; 2770-1743
• DOI: 10.1002/glr2.12076

Background The time‐series data of the Normalized Difference Vegetation Index (NDVI) is a crucial indicator for global and regional vegetation monitoring. However, the current assessment of global and regional long‐term vegetation changes is subject to large uncertainties due to the lack of spatiotemporally continuous time‐series data sets. Methods In this study, a long time‐series monthly NDVI data set with a spatial resolution of 250 m from 1982 to 2020 was developed by combining Moderate Resolution Imaging Spectroradiometer (MODIS) and AVHRR (Advanced Very High‐Resolution Radiometer) time‐series NDVI products using the Random Forest (RF) downscaling model. Results Compared to the MODIS NDVI product, the fused product shows RMSE and mean absolute error ranging from 0 to 0.075 and from 0 to 0.05, respectively, with R2 values mostly above 0.7. Conclusions The long time‐series NDVI products generated in this study are reliable in terms of accuracy and have great potential for long‐term dynamic monitoring of terrestrial ecosystems on the Qinghai–Tibet Plateau. A long time‐series monthly Normalized Difference Vegetation Index (NDVI) data set with a spatial resolution of 250 m from 1982 to 2020 was developed by combining MODIS (Moderate Resolution Imaging Spectroradiometer) and AVHRR (Advanced Very High‐Resolution Radiometer) time‐series NDVI products using the Random Forest model. The generated product is reliable in accuracy and has great potential for grassland dynamic monitoring in the Tibetan Plateau.