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Persistence and periodicity in normalised precipitation anomaly series of 91 stations over Turkey were analysed using serial correlation coefficients and power spectra. There were considerable geographical variations and inter-seasonal contrasts with respect to periodicity and persistence characteristics. Lag-one serial correlation (L-1SC ) coefficients for winter series were mostly positive and were significant at the 0.05 level for 31 stations. Annual variations at 17 stations also showed significant positive L-1SC coefficients. In contrast, year-to-year variations in spring series were characterised by negative L-1SC coefficients at most stations (significant at 18). Summer series were characterised by both positive and negative coefficients. Autumn series of most stations were random with regard to serial dependence. For winter series, long cycles of 8.4, 12-12.7, 14, 18 and 21 yr were dominant in the Marmara Transition and the Mediterranean regions, whereas short cycles of 2, 2.1, 3 and 3.2 yr were found for the Black Sea region. Major spectral peaks of most spring series occurred within spectral bands with cycles of around 2, 3, 4 and 5 yr; a 2 yr periodicity was obtained for many stations. Statistically significant negative relationships between precipitation anomalies and 500 hPa geopotential height anomalies in winter and autumn showed an apparent spatial coherence over most of Turkey. Prominent spectral peaks corresponding to about 2 and 3 yr cycles in spring precipitation anomaly series appeared to be associated with similar oscillations in spring geopotential height anomalies. A cycle of 14 yr was found for winter precipitation and geopotential height anomalies.KEY WORDS: Turkey · Precipitation · 500 hPa geopotential height · Persistence · Power spectrum · 'White' and 'red' noise continuum · Periodicity Resale or republication not permitted without written consent of the publisherClim Res 21: 2002 Time-series characteristics of climatological and hydrological observation records can be assigned to the following categories for examination: (1) A stochastic event including random variations or stable processes. (2) Deterministic components corresponding to all the non-random events in the series. Deterministic components include persistence, periodicity, trends, jumps or step-wise changes, catastrophic events (for example, disasters or extreme events), and various combinations of these. (3) A combination of random and non-random events in the series. The third category is important for long-term temporal variations in a series of climatic observations. Based on both real observational records and statistical models, it is well known that trends in climatological series are rarely linear and cycles are rarely purely sinusoidal waves. This peculiarity is found particularly in temporal variations of precipitation series. For instance, a significant downward trend has been revealed for the winter precipitation series at some stations in Turkey (Türkeş 1998). Nevertheless, this trend is not l...

This study showed that children with CIU had high psychiatric morbidity. The results suggest that the psychological status of children with CIU should be screened by clinicians and that an interdisciplinary approach combining dermatological and psychiatric evaluations is necessary for the management of CIU.

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