Precipitation reconstruction using tree-ring chronologies from Jordan and the Eastern Mediterranean Region

An international summer course in dendrochronology, ‘‘Tree Rings, Climate, Natural Resources, and Human Interaction’’, was held in Amman, Jordan, in summer 2023. Drs. Ramzi Touchan and David M. Meko from the University of Arizona Laboratory of Tree-Ring Research were course instructors. The course, with 10 students from Jordan, Algeria, Tunisia, Pakistan, Greece, and the USA, included training in core-sample collection, sample preparation, crossdating, detrending, and climate signal identification. Students applied their training in group precipitation reconstruction projects. Fifty-two Pinus halepensis core samples were collected at Dibeen Forest Reserve, Jordan, which were used to develop a tree-ring chronology (1925–2022) and then used for the reconstruction models. Two reconstructions extended precipitation for Dibeen using: (1) measured October-April precipitation data (R²adj. = 0.63), and (2) gridded November-April precipitation data (R²adj. = 0.61). A third reconstruction used the Dibeen chronology and three low-elevation tree-ring chronologies in Cyprus to extend gridded December–April precipitation data for the eastern Mediterranean region (R²adj. = 0.55). Results from the class projects demonstrated the success of reconstruction techniques in regions with sparse measured climate data and tree-ring chronologies. Future training classes in these regions will also promote the importance of understanding historic climate variability, which is essential for water resource managers and planners.