Monitoring the Dynamics of Phenological Development of Winter Wheat Using Orthogonalization of Multispectral Satellite Data

摘要

This article presents a novel methodology for monitoring and assessment of dynamics of phenological development of crop vegetation, based on orthogonal transformation of multispectral satellite images from Sentinel-2. In this work two indices using the Greenness and Wetness components of the Tasselled Cap Transformation (TCT) model are applied. The essence of the TCT model is the unitary matrix for orthogonal transformation, which is fixed for each individual sensor. The presented methodology implements a model for automated processing of Sentinel-2 images, aimed at obtaining Greenness and Wetness Tasselled Cap indices. The applied indices are defined as Normalized Differential Greenness Index (NDGI) and Normalized Differential Wetness Index (NDWNI). These indices are strongly sensitive to small changes and reflect quantitatively the vegetation dynamics in defined temporal periods. NDGI and NDWNI are especially suitable for determination of timing of different growth stages and for monitoring of the health status of the studied crops during these stages. The manifestation of the indices and their dynamics is closely related to variations of chlorophyll and moisture content, which are observed during the transition from one stage to another.