Analysis of Frost Probabilities in Aydın, Türkiye

Frost events are of particular importance for plants. Its occurrence determines growing season. Early or late frost events may cause injuries and damage in plants which have not yet entered dormancy in fall/winter, and for plants in flowering period in winter/spring. Global average temperature increase has been accompanied by changes in extreme temperature events. Observations have shown that there has been a decreasing pattern in frequencies and intensities of frost events. In this sense, it is aimed in this study to analyse probabilities of frost occurrences within the latest 30-year climatic normal period, from the cold period of 1991-1992 to that of 2020-2021, at five locations (Aydın, Kuşadası, Nazilli, Söke ve Sultanhisar) in the province Aydın, western Türkiye. Six frost indices were selected, and three temperature thresholds to define frost were considered when daily minimum temperature (TMIN) being equal to or less than 0.0, -1.2 or -2.3°C.The selected frost indices are first fall frost (FFF), last spring frost (LSF), frost period (FP), number of frost days (NFD), dates of frost occurrences (DFO) and consecutive frost days (CFD). The results revealed that Nazilli and Sultanhisar are characterized by the highest probabilities of frost in terms of frequency, intensity and duration, along with the earliest occurrence of first fall frost and latest occurrences of last spring frost, and with longest duration of frost period. On the other hand, Kuşadası and Söke have opposite characteristics in comparison to Nazilli an Sultanhisar. Aydın lies in between them. The results are expected to provide information to schedule the agricultural activities, and to avoid detrimental impacts of frost events.