Rising atmospheric drought in Central Europe: Long-term changes and dataset uncertainties in vapour pressure deficit over Czechia

Vapour pressure deficit (VPD) is a key indicator of atmospheric dryness and it plays an important role in plant water stress, stomatal behaviour, and crop productivity. In a warming climate, rising temperatures increase the atmospheric demand for moisture, leading to higher VPD. This means that plants lose water more easily, even if precipitation does not decrease. This process strengthens atmospheric drought, which remains barely represented in conventional drought assessments that mainly focus on precipitation and soil moisture. As a result, atmospheric drought becomes more pronounced, yet it is still not well captured in traditional drought assessments that mainly focus on precipitation deficits and soil moisture conditions.

This study investigates changes in VPD over Czechia using a 50-year daily datasets (1975–2024), combining station observations with widely used gridded datasets (E-OBS, ERA5, ERA5-Land). By intercomparing these datasets, we assess to what commonly used gridded datasets can reliably represent VPD variability and extremes relevant for impact studies.

Long-term changes in VPD are analysed across annual and growing-season scales, with a focus on drought-relevant characteristics such as extreme VPD events and their frequency. Trend analyses are completed by an assessment of the relative roles of temperature and humidity in driving observed changes, providing insight into the mechanisms behind increasing atmospheric demand.

The study also investigates the relationship between atmospheric dryness and soil moisture across different time scales, highlighting the interaction between atmospheric and soil drought. These results help to better understand drought processes and to assess whether commonly used datasets are suitable for drought monitoring and impact studies. Overall, this study improves our understanding of atmospheric drought in Czechia and supports the development of more comprehensive drought indicators under climate change.