European climatology of day-to-day temperature changes

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 difference (DTD). Large DTDs negatively affect human health and impact also animals and plants, hence constituting one of the many weather-related risks to society.

In this contribution, we present European climatology of DTD, including its higher statistical moments and behaviour in distribution tails, in a variety of datasets (observations – ECA&D, gridded observed datasets – E-OBS, reanalyses – NCEP/NCAR, JRA-55, 20CR). The magnitude of DTD is – quite expectedly – largest in winter and smallest in summer, and increases from the coast to the continental interior. Skewness of DTD is negative (i.e., large temperature drops prevail over large temperature rises and/or small temperature rises prevail over small temperature drops) over most of Europe in summer, while in the other seasons, there is a tendency for positive skewness to occur in the north and for negative skewness to occur in the south and over the British Isles. Kurtosis of DTD is everywhere and in all seasons larger than Gaussian; i.e., DTD distributions have heavy tails. Comparisons among datasets reveal their specific deficiencies, such as the existence of outlying unrealistic temperature values in station data that are undetected by quality check, the underestimation of the magnitude of DTD particularly by the 20CR reanalysis, and overestimated skewness in the British Isles in winter and in teh Mediterranean in summer by all reanalyses.