Abstract
Central Europe experienced several droughts in the recent past, such as in the year 2018, which was characterized by extremely low rainfall rates and high temperatures, resulting in substantial agricultural yield losses. Time series of satellite earth observation data enable the characterization of past drought events over large temporal and spatial scales. Within this study, Moderate Resolution Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) (MOD13Q1) 250 m time series were investigated for the vegetation periods of 2000 to 2018. The spatial and temporal development of vegetation in 2018 was compared to other dry and hot years in Europe, like the drought year 2003. Temporal and spatial inter- and intra-annual patterns of EVI anomalies were analyzed for all of Germany and for its cropland, forest, and grassland areas individually. While vegetation development in spring 2018 was above average, the summer months of 2018 showed negative anomalies in a similar magnitude as in 2003, which was particularly apparent within grassland and cropland areas in Germany. In contrast, the year 2003 showed negative anomalies during the entire growing season. The spatial pattern of vegetation status in 2018 showed high regional variation, with north-eastern Germany mainly affected in June, north-western parts in July, and western Germany in August. The temporal pattern of satellite-derived EVI deviances within the study period 2000–2018 were in good agreement with crop yield statistics for Germany. The study shows that the EVI deviation of the summer months of 2018 were among the most extreme in the study period compared to other years. The spatial pattern and temporal development of vegetation condition between the drought years differ.
Highlights
The 2018 growing season was extremely warm and dry in central Europe, and the months April to August were amongst the most extreme in the recent past regarding meteorological parameters [1]
Since our own pre-analyses indicated a higher robustness of the Enhanced Vegetation Index (EVI) in comparison to other Vegetation indices (VI) such as NDVI, this metric was chosen for further analysis
Sixteen-day composites of EVI and the corresponding pixel reliability layers were extracted from the Moderate Resolution Spectroradiometer (MODIS) product MOD13Q1, version 6 [33]
Summary
The 2018 growing season was extremely warm and dry in central Europe, and the months April to August were amongst the most extreme in the recent past regarding meteorological parameters [1]. It is very likely that heat waves will be more intense, more frequent, and last longer, and that risk levels regarding water restrictions and damages from extreme temperatures for Europe will increase [2,3]. With 2 ◦C of global warming, one out of every two summer months in Europe could show higher temperatures than ever observed under current climate conditions [4]. Several recent studies show that, by the end of this century, drought events will become more frequent all over Europe [5,6,7]
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