Standardized Precipitation Index Reconstructed from Turkish Tree-Ring Widths

Abstract

May-July Standardized Precipitation Index (SPI) for the land area of most of Turkey and some adjoining regions are reconstructed from tree rings for the period 1251-1998. The reconstruction was developed from principal components analysis (PCA) of four Juniperus excelsa chronologies from southwestern and south-central Turkey and is based on reliable and replicable statistical relationships between climate and tree ring growth. The SPI reconstruction shows climate variability on both interannual and interdecadal time scales. The longest period of consecutive drought years in the reconstruction (SPI threshold ≤−1) is 2 yr. These occur in 1607-1608, 1675-1676, and 1907-1908. There are five wet events (SPI threshold ≥+1) of two consecutive years each (). A 5-yr moving average of the reconstructed SPI shows that two sustained drought periods occurred from the mid to late 1300s and the early to mid 1900s. Both episodes are characterized by low variability.

Tree‐ring reconstructions of precipitation and streamflow for north‐western Turkey

“…Table IV compares extreme dry and wet years identified in our reconstructions with those found in other tree-ring reconstructions and chronologies for Turkey (Kuniholm, 1996;D'Arrigo and Cullen, 2001;Touchan et al, 2003Touchan et al, , 2005aHughes et al, 2001), as well as historical archives (Purgstall, 1983;Panzac, 1985; Ottoman Archives of the Prime Minister of Turkey, 1850Turkey, -1923Inalcik, 1997).…”

“…Hughes et al (2001) found that extreme signature years in tree-ring data from the Aegean region (including northern Turkey, Greece and Georgia) coincided with recorded April-June precipitation and sea level pressure anomalies. Touchan et al (2003Touchan et al ( , 2005a demonstrated correspondence between Turkish tree-rings and atmospheric circulation patterns during extreme years. Although Touchan et al's study partly overlaps that reported herein, they did not include data from our immediate north-western Turkey study region.…”

“…This method has been used previously in dendroclimatological reconstructions for Turkey (Touchan et al, 2003(Touchan et al, , 2005a.…”

“…Both reconstructions primarily emphasize high-frequency fluctuations, and thus decadal or longer-term trends in precipitation or streamflow were not retained in this analysis and were not discussed herein. In order to investigate extreme drought and flood events in the reconstructions, we used positive and negative anomaly thresholds, defined (as previously noted) as those exceeding 85 (86 mm) and 115% (116 mm), respectively (Touchan et al, 2003(Touchan et al, , 2005a.…”

Reconstruction of the rainy season precipitation in central Jordan

“…In the literature, several recent dendroclimatological studies have focused on analysing droughts in the eastern Mediterranean (e.g. Akkemik, 2000;Touchan et al, 2003Touchan et al, , 2005Touchan et al, , 2007Akkemik et al, , 2008; however, few studies have considered the analysis of droughts in the region of Jordan (e.g. Touchan et al, 1999).…”