Developing probabilistic chilling-duration maps in the Mediterranean region through using different chilling estimation methods

This study, conducted in the Eastern Mediterranean Region of Turkey, aimed at determining chilling durations in the region by using different chilling estimation methods and developing chilling maps at 50%, 80% and 95% probability levels. Long term yearly chilling durations for classic and Aron methods and chilling hour accumulations for chill unit method of 26 meteorological stations, located point-wisely in the study area, were calculated by running a computer program which has been developed for this purpose. Long-term hourly temperature and daily maximum and minimum temperature series of meteorological observation stations were utilized to obtain long term yearly chilling duration -as hours- and chilling accumulation -as chill units- series. The correlation between long-term series of Aron or so-called Costello and classic method was investigated and the correlation coefficient map was developed to obtain spatial distribution pattern of association. It was found that the association is statistically significant (P=0.05) over the study area, except for Afşin meteorological station. Frequency analyses of the series of chilling hours and chilling units -calculated for each station using the tree chilling estimation methods- were performed and the best fitted probability distribution functions were determined for each of tree chilling series at each station. It was found that the majority of stations utilized in the study fitted to Gumbel and log-normal frequency distributions. Chilling hours and chill units for 95%, 80% and 50% probability levels were estimated for tree different chilling estimation methods at each meteorological station. Probabilistic chilling-duration maps for each chilling estimation method were developed and spatial distribution patterns of chill units and chilling hours were determined over the study region, and interpreted thoroughly. It was found that chilling values are increasing too fast towards inner parts of the study area, viz. from the Mediterranean climatic zone to terrestrial climate. Anamur, Silifke, Mersin, Karataş and Yumurtalık meteorological stations and their nearby neighborhood were found to be the most critical places in terms of chilling durations in the region.