Satellite monitoring of winter rapeseed crops based on sentinel‑2 data to assess vegetation dynamics and spatial heterogeneity in the Vologda Region

The paper presents the results of monitoring winter rapeseed crops in the growing season of 2025 (May – September), based on data from the Sentinel-2 multispectral satellite system (ESA Copernicus mission). For the analysis, L2A level scenes (atmospherically adjusted) were used, which were pre-processed: cloud masking, mosaic merging, and cropping along the contour of the field. The values of the NDVI (Normalized Difference Vegetation Index) index as an integral indicator of the state of crops have been calculated. Statistical metrics (mean, median, standard deviation, coefficient of variation, percentiles), as well as visualization of data through cartograms with a fixed and contrasting scale (μ ± σ) were used to assess the spatiotemporal dynamics. We found that the NDVI of crops per season varied in the range of 0.1–0.8, demonstrating characteristic phases of development: spring resumption of vegetation (NDVI 0.3–0.4), budding and maximum biomass (NDVI up to 0.7–0.8, minimum in-field variability), flowering phase (decrease in NDVI to 0.5) and subsequent maturation with a sharp drop in values (<0.2). It is shown that cloud cover significantly limits the practical applicability of satellite monitoring: out of 42 scenes per season, only 32 were suitable for analysis. Despite this, Sentinel-2 data revealed persistent spatial anomalies and areas of potential productivity decline. We noted that it is necessary to combine satellite observations with aerial photography and agrochemical surveys to ensure prompt and detailed monitoring of the condition of crops. Contrast visualization is presented to identify weak anomalies in case of heterogeneity of vegetation within one elementary area of the agricultural landscape. The adaptation of statistical metrics for the analysis of spatial heterogeneity has been performed.