Introduction

ENSO is one of the most important teleconnection patterns in the southern Hemisphere, affecting the worldwide climate. This phenomenon happens with the appearance of a warm water current in the central and eastern tropical Pacific Ocean. walker first demonstrated in 1924 that air pressure between the eastern and western regions of the Pacific Ocean oscillates like a seesaw., El Nino is more than a sudden warm water current along the coast of Peru. Because it is able to increase the temperature of a vast realm of the tropical pacific and can change wind direction and ocean current. As a result, clematises don't consider El Nino a single phenomenon, the southern oscillation Index (SIO)Is used to indicate the status of southern Oscillations, representing the strength or weakness of the walker circulation. this index is calculated by measuring the pressure difference between Darwin, Australia and Tahiti in the eastern Pacific Ocean.

Methodology

Dogonbadan located in Kukillueh, we used average temperature and precipitation for 1985-2006, And the numerical data of ENSO index.  to evaluate the impact of El Nino on the climate of Dogonbadan, the warm (EL Nino) and cold (La Nino) periods of Enso index were first identified using the numerical values. Subsequently, the effect of the El Niño event on the temperature and precipitation was studied by comparing the numerical values of the ENSO index with the temperature and precipitation data, and the results were analyzed graphically. Furthermore, the correlation between the Southern Oscillation Index and the temperature and precipitation was calculated and analyzed using Pearson's correlation coefficient.

Results

it can be observed that the ENSO index experienced significant fluctuations on a monthly scale., La Niña occurred in the years 1988, 1989, 1996, 1999, 2000, 2001, and 2006, while El Niño occurred in the years 1987, 1992, 1993, 1994, 1997, 1998, 2002, 2003, and 2005In some years, the Southern Oscillation Index was in a neutral state, and despite considerable fluctuations throughout a year, it cannot be considered as an occurrence of El Niño or La Niña, such as in the years 1985 and 1986.
On an annual scale, the occurrence of the El Niño does not affect the increase or decrease of temperature. because in some years of El Niño occurrence, the temperature has a decreasing trend, while in other years it has an increasing trend. a comparison between the ENSO and the average monthly temperature, through calculating the Pearson correlation coefficient, does not show a significant relationship., it can also be said that on a monthly scale, the occurrence of the El Niño phenomenon does not have a significant effect on the temperature. Regarding the impact of El Niño on precipitation there is a significant relationship between the annual value of the Southern Oscillation Index and the total annual precipitation., there is a linear trend of increasing precipitation, which often coincides with the occurrence of El Niño, while a decrease in precipitation is seen during the occurrence of La Niña. The calculation of the Pearson correlation coefficient between the annual value of the ENSO index and the total annual rainfall reveals the influence of precipitation from the occurrence of the ENSO phenomenon. The inverse relationship between these two indicates a relative increase in precipitation during El Niño and a decrease La Niña

Discussion

The occurrence of ENSO can influence the climate of various regions of the globe by affecting Rossby waves, monsoon systems, ocean currents, and wind patterns.
Considering the climatic situation of Iran and its location in the world's desert belt, which faces a lack of precipitation in most areas, along with the negative effects that periods of drought and excessive rainfall have on the country's water resources and consequently their direct impact on agricultural production and people's livelihoods, examining the effects of ENSO on the climate of the country seems important. Given this significance, this research analyzed the effects of this phenomenon on the climate

Conclusion

The results indicated that on an annual scale, the linear trend of temperature has been decreasing; however, no significant correlation with El Niño and La Niña events was found. On a monthly scale, a comparison between the ENSO index and average monthly temperature through Pearson correlation coefficient calculation did not show a significant relationship between these two variables. Therefore, the influence of El Niño events on the temperature city is very minimal. Unlike temperature, the impact of El Niño on precipitation showed a linear increasing trend, generally with an increase in precipitation coinciding with the occurrence of El Niño and a decrease during La Niña events. There is a good correlation between the annual ENSO index and the total annual precipitation at the Dogonbedan station, indicating the influence of precipitation from the occurrence of the ENSO phenomenon. Based on research conducted by other researchers, the effect of ENSO on climatic elements, especially temperature and precipitation in the country, has been somewhat different.