Inter‐decadal variability in daily rainfall at Durham (UK) since the 1850s

Abstract

Abstract:Records of daily rainfall at Durham (UK) are analysed from 1850 to the present. The most notable wet period is the 1870s, followed by a protracted period of below-average rainfall. Other than the 1870s, summers tended to be much wetter than winters during the latter part of the 19th century. In the 20th century, summers had become drier and winters wetter. To analyse large daily totals, three thresholds, 15, 22.6, and 25 mm, are used. For all three indices, the frequency of large falls was highest from the 1860s to the 1880s, followed by a low frequency in the 1900s. Since then, the general trend has been for totals to gradually increase. There is a clear division for the annual total rainfall, number of heavy falls (≥15 mm), and proportion of total rainfall provided by heavy falls in the winter (154 mm, 147 days, 12%, respectively) and spring (140 mm, 180 days, 16%) seasons in comparison to the summer (181 mm, 329 days, 28%) and autumn (186 mm, 304 days, 23%) seasons. However, since 1990, winter total rainfall (164 mm) has overtaken the summer total (154 mm). Furthermore, since 1990, heavy falls of rain in spring (23 days) and the proportion of total rainfall (26%) have overtaken summer heavy rain (17 days) and the proportions of rainfall in both summer (24%) and autumn (24%). In terms of heavy rainfall, winters have seen only a small increase in its relative importance, whereas its relative importance declined from the 1960s to the mid-1990s for summers. The widely recognised increase in the winter : summer ratio of rainfall since the 1960s is clearly evident. Overall, there has been a narrowing of the differences between seasons in terms of the frequency of heavy falls of rain in the 1990s.

Spatial and temporal variability of extreme precipitation in Poland in the period 1951–2006

“…In winter, in many areas of Europe strong increases of extreme precipitation were recorded (Osborn et al, 2000;Schmidli and Frei, 2000;Schönwiese et al, 2003;Moberg and Jones, 2005;Hundecha and Bárdossy, 2005;Ramos and MartinezCasasnovas, 2006;Burt and Horton, 2007;Trömel and Schönwiese, 2007). In Poland, increasing trends of only one index (5dayT) occurred more often than trends towards a decrease; other indices (90pT, 90pNoD, 95pT and 95pNoD) showed some increasing trends but only at few stations.…”

“…The directions of trends in climatic elements depended not just on the long-term period selected, but also on the season studied. Seasonally focused research on extreme precipitation in Europe reveals increasing trends in the winter season in the central and western parts of the continent (Osborn et al, 2000;Schönwiese et al, 2003;Moberg et al, 2006;Burt and Horton, 2007). On the Iberian Peninsula, contrary to the trends observed elsewhere in Europe, decreasing trends dominate in wintertime (Garcia et al, 2007).…”

Changing temperature and rainfall gradients in the British Uplands

“…Dates are for those data used in the present study; the records of some stations started earlier than the dates given 2000, since increases in winter rainfall and decreases in summer rainfall are well documented over this time (Osborn et al 2000, Osborn & Hulme 2002, Burt & Horton 2007, Maraun et al 2008. To provide a longer-term perspective, the much longer time series for both Plymouth and Princetown from 1912 to 2000 have also been compared.…”

“…However, poor model performance means there is less certainty about summer rainfall, with both increases and decreases in extreme precipitation predicted. There has indeed been a widespread shift in the pattern of UK rainfall towards more heavy falls of rain in winter and fewer in summer in recent decades (Osborn et al 2000, Osborn & Hulme 2002, Burt & Horton 2007, Maraun et al 2008, and these changes are reflected in seasonal rainfall totals. Malby et al (2007) identified a clear change in the seasonality of orographic rainfall in the Lake District of northern England and speculated that this was related to the incidence of higher-intensity events, but otherwise there has been little attention paid to changes in upland rainfall gradients associated with this changing seasonality of heavy rainfall.…”

Importance of long-term monitoring for detecting environmental change: lessons from a lowland river in south east England

“…This interest in long-term trends in nitrate concentrations matches recent interest in long-term hydrological trends, for example in rainfall (e.g. Burt and Horton, 2007) and streamflow (e.g. Dixon et al, 2006).…”