Daily dataset of 20th‐century surface air temperature and precipitation series for the European Climate Assessment

Abstract

We present a dataset of daily resolution climatic time series that has been compiled for the European Climate Assessment (ECA). As of December 2001, this ECA dataset comprises 199 series of minimum, maximum and/or daily mean temperature and 195 series of daily precipitation amount observed at meteorological stations in Europe and the Middle East. Almost all series cover the standard normal period 1961-90, and about 50% extends back to at least 1925. Part of the dataset (90%) is made available for climate research on CDROM and through the Internet (at http://www.knmi.nl/samenw/eca).A comparison of the ECA dataset with existing gridded datasets, having monthly resolution, shows that correlation coefficients between ECA stations and nearest land grid boxes between 1946 and 1999 are higher than 0.8 for 93% of the temperature series and for 51% of the precipitation series. The overall trends in the ECA dataset are of comparable magnitude to those in the gridded datasets.The potential of the ECA dataset for climate studies is demonstrated in two examples. In the first example, it is shown that the winter (October-March) warming in Europe in the 1976-99 period is accompanied by a positive trend in the number of warm-spell days at most stations, but not by a negative trend in the number of cold-spell days. Instead, the number of cold-spell days increases over Europe. In the second example, it is shown for winter precipitation between 1946 and 1999 that positive trends in the mean amount per wet day prevail in areas that are getting drier and wetter.Because of its daily resolution, the ECA dataset enables a variety of empirical climate studies, including detailed analyses of changes in the occurrence of extremes in relation to changes in mean temperature and total precipitation.

Spatial and temporal variability of the daily rainfall regime in Catalonia (northeastern Spain), 1950–2000

“…These positive trends are due to an increase in extreme precipitation. A European study presented by Klein Tank et al (2002) for the period 1946-99, similar to that analysed in the present paper, shows ADR trends for 195 gauges in winter. In Spain, only two gauges, one of them in Catalonia, present a significant positive trend.…”

Statistical modeling of hot spells and heat waves

“…Moreover, since detecting possible trends in hot spells was a goal, we needed to assume homogeneity of the data series to justify fitting the proposed model. Klein Tank et al (2002) mentioned that it is not untypical for climatic time series to be subject to certain inhomogeneities as, for example, changes in station location or instrumentation. Thus, one should be aware that any of the detected trends could be artifacts of these inhomogeneities, rather than reflecting real climate change.…”

Inconsistency between atmospheric dynamics and temperatures during the exceptional 2006/2007 fall/winter and recent warming in Europe

“…[4] Daily temperature minima averaged over 25 European stations (data from the European Climate Assessment project [Klein-Tank et al, 2002]) and over the months of September to November (SON), underwent departures of +2.9°C from the 1900 -2006 average (Figure 1a). Similar anomalies are found with maximal temperatures.…”