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Spectral analysis of time series cycles of the durability of rainy season over Iran
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Gholamreza Barati1   , Maryam Barati * 1, Alireza Shakiba1 |
| 1- Shahid beheshti Univercity |
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Abstract: (553 Views) |
| One of the major manifestations of climate change in recent decades is the change in precipitation in different parts of the world. Since this climate parameter has a rebellious nature, recognizing its oscillating behavior is a necessity in the field of environmental planning in order to achieve sustainable development. Spectral analysis technique is an efficient method of identifying and understanding the overt and covert behavior of climatic elements and extracting and analyzing climatic fluctuations. Therefore, in the present study, using the daily precipitation data of 108 synoptic and rain gauge stations in the country, first the beginning and end of precipitation periods in the wet season (September-May) in 1990-2015 were extracted and then According to it, the longevity of the rainy season in the country was achieved in all stations. In the next step, using programming facilities in MATLAB software, the distribution of variances in all possible wavelengths at a significance level of 95%, in a time series of 26 years was obtained and finally in order to discover the spatial distribution of important and dominant cycles in software Arc Gis 10 software was mapped. The results showed that these fluctuations in the southern regions of the country are mainly 2 to 4 years and shorter and have less diversity and in the northern regions are more diverse and often 4 to 8 years. In general, significant fluctuations governing the longevity of the country's rainy season in the wet period of the year are mainly short-term and with a return period of 2 to 4 years, which is commensurate with large-scale fluctuations in oceanic climate indicators and is related to remote connection patterns. Also, the role of altitudes and distance and proximity to the sea in the diversity of cycles governing the northern and western half of the country is also significant. |
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| Keywords: Spectral analysis, harmonic analysis, durability of the rainy season, time series |
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Full-Text [PDF 1326 kb]
(141 Downloads)
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Type of Study: Research |
Subject:
Special
Received: 2020/08/15 | Accepted: 2021/03/3 | Published: 2023/10/2
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