ALBERT

Description: Substantial efforts have been made in climatic analyses of climate means and extremes, while much less has been done in understanding short-term (intraseasonal and synoptic-scale) variability. One particular aspect of short-term atmospheric variability is day-to-day temperature (DTDT) change. Large DTDT changes negatively affect human health and impact also animals and plants. It is known that the distribution of DTDT changes in central Europe is asymmetrical: large temperature increases prevail over large decreases in winter, and vice versa in summer. The opposite is true for small DTDT changes: in winter, small decreases prevail over small increases. In this contribution, we present European climatology of DTDT changes, including their higher statistical moments and behaviour in distribution tails, in a variety of datasets (observations, gridded observed datasets, reanalyses). We also analyze two mechanisms causing their asymmetry. The first mechanism is passages of atmospheric fronts, which contribute to the asymmetry in large DTDT changes: cold front passages are responsible for more frequent and stronger temperature drops than increases in summer, while warm front passages cause temperature increases to occur more often than drops in winter. The second mechanism consists in circulation conditions conducive to radiative warming in summer or radiative cooling in winter, which stay behind the asymmetry in small DTDT changes. The analysis of mechanisms is performed for all European land gridpoints of the E-OBS database.