Recent changes in persistence over Europe and the World in reanalysis dataset

The intensity and frequency of persistent heat waves and droughts have increased over the last few decades. While some of the changes may be attributed to natural variability, it is a known reality that climate change contributes to these tendencies. According to the Fifth Assessment Report of the IPCC, these anomalies are projected to be accelerated and impact humans, ecology, agricultural events, and natural systems.

Understanding the spatiotemporal structure of heat waves is crucial to deciding what environmental change will affect the above-mentioned impacts. In this study, the temporal autocorrelation of near-surface temperature and 850 hPa geopotential height from daily ERA-5 reanalysis data is examined. The focus is on the period from 1979 to 2019. To explore this 41-year long dataset, spatio-temporal trend analysis is also conducted along with autocorrelation. The trends are inspected under 3, 5, and 7-day lag autocorrelations.

In this context, the summer of 2003 shows a very high autocorrelation of geopotential height over central Europe in this analysis, which is consistent with a persistent heat wave that resulted in a death toll. Along with the yearly analyzed data, the trends are calculated both as a whole and divided into intervals. The trend analysis yields high results that cluster around Northern Africa, the Middle East, Middle China, and Middle Russia in the summer season. Furthermore, in the winter season, Siberia, Middle Africa, and the northern part of South America reflect high trends.