资源环境科技发展态势分析平台

In this study, we examine the relationship between short-and long-term effects of precipitation deficits, integrated in a drought index called 'Joint Deficit Index (JDI)', and tree-ring growth of oak trees (Quercus infectoria) in the Javan-Roud region, Kermanshah province (Iran). Precipitation data from regional climate stations cover the period 1968-2008, and the tree-ring width chronology span over the period 1818-2008. This chronology is highly correlated with the JDI (January-September) series for the instrumental period (P<0.01). Therefore, the regional JDI was reconstructed using a simple linear regression model which accounts for 40% of JDI (January-September) variances over the instrumental period. Reconstructed drought periods persisted on average for 2 years, and some severe drought lasted for 3-4 years. However, one 7-year drought was reconstructed over the period 1923-1929. The most severe droughts occurred in the periods 1960-1963 and 1999-2001. While the reconstructed JDIs have no significant correlation with the North Atlantic Oscillation, a significant negative correlation was observed with the Southern Oscillation Index in November and December of pre growth during the common period from 1877 to 2008. An appropriate agreement was found between our reconstruction and historical famines in Iran and also reconstructed results from neighbouring countries in the east (China) and west (Turkey and other countries around the Mediterranean Sea), particularly for the most severe droughts. The highest agreement was achieved with regions in the pathway of westerly storm tracks travelling via the Mediterranean region into Iran.