Evaluating the Relationship Between Solar Cycle and the Occurrence of El Niño-Southern Oscillation
| dc.contributor.advisor | Elias Lewi (PhD) | |
| dc.contributor.advisor | Moges Wassie (PhD) | |
| dc.contributor.author | Tsion Lema | |
| dc.date.accessioned | 2025-08-17T21:23:47Z | |
| dc.date.available | 2025-08-17T21:23:47Z | |
| dc.date.issued | 2024-06 | |
| dc.description.abstract | Quasi-periodic climate patterns like El Niño and La Niña exert significant impact on global weather patterns. As the primary source of energy for the Earth's climate system, changes in solar activity, including the 11-year solar cycle, have been hypothesized to influence the complex ocean-atmosphere interactions that govern ENSO dynamics. Despite extensive research efforts, a universally accepted theory elucidating the causes of these phenomena remains unclear. However, recent discoveries hint at a potential link between this quasi-periodic event and the solar cycle, sparking ongoing debate among researchers worldwide. In an effort to furnish additional context to this finding, we have conducted an analysis utilizing monthly average sunspot count data spanning from 1964 to August 2023, in conjunction with the Oceanic Niño Index of 3.4, from the same period. The data sets are first de-trended to remove any linear trend and filtered to remove possible noise in the high frequency spectrum. Then both data sets are transformed into the frequency domain. The amplitude spectrums of the two data sets are then analyzed and the coherency between them is explored to find if there is any relationship between the two data sets in the different frequency spectrums. Furthermore, the phase lag is analyzed, to see if there is discernable lag between the two data sets. The result revealed a statistically significant, high degree of coherency between sunspot activity, and the occurrence of El Niño events within certain frequency ranges. Specifically, the results showed a coherency at the 99% confidence threshold level, mainly with a periodicity of approximately 11.59 and 5.2 years, corresponding to the well-established 11-year and half the period of the solar cycle respectively. Taking into consideration the resolution capacity of the data, the analysis also reveals a monthly lag between changes in sunspots and the occurrence of ENSO events. Finally, the findings suggest that sunspot activity and El Niño events are not independent, isolated phenomena, but rather exhibit a meaningful, interconnected relationship. Numerous fields will benefit from this outcome, particularly the agricultural and climate forecasting sectors. | |
| dc.identifier.uri | https://etd.aau.edu.et/handle/123456789/6853 | |
| dc.language.iso | en_US | |
| dc.publisher | Addis Ababa University | |
| dc.subject | Evaluating the Relationship | |
| dc.subject | Solar Cycle | |
| dc.subject | Occurrence of El Niño-Southern Oscillation | |
| dc.title | Evaluating the Relationship Between Solar Cycle and the Occurrence of El Niño-Southern Oscillation | |
| dc.type | Thesis |