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Parametric and nonparametric correlation analysis of Indian Ocean Dipole (IOD) Index and drought and wet years in Iran
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Zahed Deldarzehi1   , Peyman Mahmoudi * 1, Mahmood Khosravi1 |
| 1- Department of Physical Geography, Geography and environmental Planning Faculty, University of Sistan and Baluchestan, Zahedan, Iran |
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Abstract: (132 Views) |
| The research mostly aims to investigate the correlation analysis of the Indian Ocean Dipole (IOD) index and drought and wet years in Iran on a monthly basis. To this aim, a correlation analysis was performed between the Standardized Precipitation Index (SPI) of 63 synoptic stations in Iran and the Indian Ocean Dipole (IOD) index values using the Pearson product-moment correlation coefficient and Spearman's rank correlation coefficient. The findings suggested that in autumn, a moderate positive correlation was noted between the Indian Ocean Dipole (IOD) Index and drought and wet years in Iran in a one-month lag. In other words, droughts of the autumn season in Iran occurred in the negative phase while wet years in the positive phase of this index. In the winter, however, no significant correlation was noted between the drought and wet years in Iran and the Indian Ocean Dipole (IOD) index. It was also noted in springs that there was a negative correlation between drought and wet years in Iran, especially in its southern parts and the Indian Ocean Dipole (IOD) index. In other words, the droughts in this season in Iran occurred in the positive phase while the wet years in the negative phase, i.e., exactly the opposite of the relationship seen in the autumn. |
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| Keywords: Tele-connection, Pearson product-moment correlation coefficient, Spearman's rank correlation coefficient, time lag, drought, wet year, Iran |
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Type of Study: Research |
Subject:
Special
Received: 2022/02/21 | Accepted: 2024/10/8
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