Modeling European hot spells using extreme value analysis

By definition, extreme temperatures are rare, and yet the theory of extreme value statistics has seldom been applied to quantify the influence of atmospheric blocking on hot spells. Similarly, a comparison of the relative influence of other well-known atmospheric drivers, such as the North Atlantic Oscillation (NAO) and the El Nino-Southern Oscillation (ENSO), has seldom been explored.

We applied a novel combination of extreme value and geometric distributions to observed daily temperature maxima from 74 stations across Europe, covering 1951-2010, to establish a stationary model of the expected magnitude, frequency and duration of hot spells that did not explicitly account for atmospheric drivers. Monthly time series of NAO, ENSO and 4 coherent atmospheric blocking regions were then incorporated as non-stationary covariates in the distribution parameter estimates to assess the dependence of hot spells on atmospheric covariates.