Summer Precipitation Variability Analysis and its Relationship with the Indian Ocean Dipole (Case Study: South-East of Iran)

• Published in: نشریه جغرافیا و برنامه‌ریزی Vol. 22; no. 65; pp. 45 - 62
• Main Authors: Mohsen Armesh, Mahmood khosravi, Mohammad Saligheh
• Format: Journal Article
• Language: Persian
• Published: University of Tabriz 01-10-2018
• Subjects: iod index; south east of iran; summer precipitation; variability; wavelet transform
• ISSN: 2008-8078; 2717-3534

This study aimed to evaluate the variability of summer precipitation in the South East of Iran was selected stations and the precipitation associated was investigated with IOD index. For this purpose was used weekly precipitation data from June to September stations of Zahedan, Kerman, Bandar Abbas, Iranshahr and Bam and weekly IOD index data. The method of this study is the correlation coefficient and discrete wavelet analysis. The results showed that in the positive phase of the IOD Index, warm air and humid of West Africa, sucked by low pressure the Persian Gulf and Pakistan and conditions creates convection in southeast of Iran, while IOD negative phase, in addition to shiftting the intertropical Convergence Zone, low pressure Persian Gulf and Pakistan are gone and West Indian Ocean for cooling than normal, stable atmosphere reigns. Summer precipitation correlation analysis between Bandar Abbas and Iranshahr with IOD index showed the strongest association. After the precipitation signal analysis of the stations showed of the Zahedan station on Level 4 and 3, respectively, at 99 and 95% was related to IOD index. The following series Kerman and Bam precipitation did not show any relationship with IOD index. Data analysis by the discrete wavelet transform showed that the most important cycle repeating 11-year occurred in the IOD index. Zahedan and Iranshahr showed periodic cycles relatively similarly. In Kerman was appeared 7-year cycle dominant and in Bandar Abbas and Bam the 11-year cycle. The process of reducing the number of weeks along with summer precipitation in the form of stations is contrary to the IOD index. But the increased intensity of precipitation stations is directly related to this index. Also Bandar Abbas, Iranshahr and Zahedan have more balanced precipitation cycles, but summer precipitation anomalies are intense in Kerman and Bam.