Seasonality effect on trend and long-term persistence in precipitation and temperature time series of a semi-arid, endorheic basin in Central Anatolia, Turkey

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In climate change research, it is vital to have knowledge about future changes in the trends of climatological time series. The purpose of this study is to look at the effect of seasonality on the trend and long-term persistence of precipitation and temperature time series in the Konya Endorheic Basin, a semi-arid basin in central Anatolia, Turkey. Seasonal-trend decomposition by locally estimated scatterplot smoothing was used to obtain a seasonality adjusted time series, and a comparative analysis with the original series was performed. The Mann–Kendall test and simple linear slope were used to determine monotonic trends. To observe long-term persistence, Hurst exponents were computed using the rescaled range analysis approach. The Onyutha trend test was then used to investigate the sub-trends. As a result, there is a significant increase in temperature. Precipitation is increasing in the west and east of the basin while decreasing in the north and south. The magnitude of the monotonic and sub-trend is enhanced by seasonal adjustment. Meanwhile, in the seasonally adjusted dataset, the Hurst exponent grew dramatically, reinforcing the long-term persistence. Seasonality has less of an impact on precipitation, which is more affected by local variability, than temperature.