This paper studies the impact of northwest Indian Ocean (NIO) sea surface temperature (SST) anomalies between the regions 0–29°N and 45–80°E and El Niño–Southern Oscillation (ENSO) on the winter precipitation in Iran. The data include monthly precipitation from 45 weather stations in Iran, monthly NIO SST with a 2° horizontal resolution and Southern Oscillation Index (SOI) for a 40-year period (1975–2014). This study utilizes canonical correlation analysis and partial correlation to investigate the simultaneous relationship between SST, SOI, and winter precipitation variability. A running correlation method is also used to test the stationarity of these relationships. Analyses of the results reveal that both NIO SST and ENSO index are significantly correlated with the winter precipitation in Iran but with opposite sign. Moreover, a clear variability exists in the correlations revealing a distinct non-stationarity in the relationship over time. The results of partial correlation analysis suggest that the ENSO index has a stronger effect on the winter precipitation in Iran than NIO SST.

本文研究了北印度洋（NIO）海面温度（SST）异常在0–29°N和45–80°E之间的区域以及厄尔尼诺—南方涛动（ENSO）对伊朗冬季降水的影响。数据包括伊朗的45个气象站的月降水量，水平分辨率为2°的月度NIO SST和40年期间（1975-2014年）的南方涛动指数（SOI）。这项研究利用规范相关分析和偏相关来研究SST，SOI与冬季降水变化之间的同时关系。运行相关方法也用于测试这些关系的平稳性。对结果的分析表明，NIO SST和ENSO指数均与伊朗的冬季降水显着相关，但标志相反。此外，相关性中存在明显的可变性，揭示了该关系随时间的明显非平稳性。偏相关分析的结果表明，ENSO指数对伊朗冬季降水的影响要强于NIO SST。