Trend analysis of precipitation data in Turkey and relations to atmospheric circulation: (1955-2013)

• Main Authors: Topuz, Muhammet, Feidas, Haralambos, Karabulut, Murat
• Format: Text
• Language: English
• Published: Italian Journal of Agrometeorology 2021
• Subjects: Kendall; North Atlantic; North Atlantic oscillation
• Online Access: https://dx.doi.org/10.13128/ijam-887; https://riviste.fupress.net/index.php/IJAm/article/view/887

Climate change is expected to significantly affect the precipitation regime of the Mediterranean basin where Turkey is located. This study investigates the trends of seasonal and annual precipitation time series of 29 rain gauge stations of the Turkish State Meteorological Service (TSMS) for the period 1955–2013, using two statistical tests based on a simple linear regression model and the well-known Mann-Kendall test. The non-parametric Sen’s slope estimator was used to estimate the slope of the trend. The results of the trend analysis at the national scale for the entire period 1955-2013 revealed a clear significant upward trend of 5.5%/decade only for autumn precipitation. No significant trend was found in the annual and other seasonal time series. The investigation of abrupt precipitation changes in the series averaged over Turkey resulted in a distinct significant upward trend in autumn precipitation starting in 1984 and a downward trend in winter precipitation initiating in 1971, which, however, seems to start reversing after 1996. The influence of atmospheric circulation on the precipitation variability in Turkey was assessed using five atmospheric circulation indices: North Atlantic Oscillation Index (NAOI), Mediterranean Oscillation Index (MOI), Mediterranean Circulation Index (MCI), Eastern Mediterranean Pattern Index (EMPI) and North-Sea Caspian Pattern Index (NCPI). The analysis of the circulation indices revealed an important link between precipitation variability in Turkey and some atmospheric teleconnection patterns, expressed mainly by the indices of NAOI and MCI. : Italian Journal of Agrometeorology, No. 2 (2020)