Introduction

Today, the topic of climate change is one of the significant issues of climate research. Forecasting the trend of climate change for environmental management. And survival of human societies is important. In this research, the statistics of Sepidan in a statistical period of 19 years (2005-2023) have been used. the trend and type of changes in temperature and rainfall were analyzed monthly, seasonally and annually. The results showed that the average temperature, the average minimum temperature and the maximum annual temperature have a decreasing trend, and the largest decrease with a statistic of -0.64 is to maximum temperature. Seasonal changes of average temperature showed that spring has a decreasing trend and other seasons have no trend. The average minimum temperature in the spring and summer has a decreasing trend, and the average maximum temperature in the three seasons of spring, summer and autumn has a decreasing trend. The monthly average temperature changes have a decreasing trend only in July and September, and there is no trend in the rest of the months. The average minimum temperature in January, July, August, September and October has a decreasing trend and the rest of the months have no trend. The average maximum temperature of March, April, May and November has no trend and the rest of the months have a decreasing trend. The results of the analysis of rainfall changes indicate that the annual and seasonal averages have no trend, and the monthly average rainfall in the hot months of the year, i.e., May, June, July and September, has a decreasing trend and the rest of the months have no trend.
 

Methodology

In order to investigate and explain the manner and time of changes in time series we used non-parametric method i.e., Mann-Kendall.
In this research, due to the Importance of climate change and global warming and changes in energy, climatic data such as temperature and rainfall of Sepidan (2005-2023) have been used monthly, annually and seasonally to find out the variability.
 

Results

Results show that on annual scale, the average temperature, the average maximum temperature and the average minimum temperature has a decreasing trend, seasonal analysis of temperature parameters shows that some seasons have trend and some not. Average temperature in spring and summer has a decreasing trend and winter
and autumn are without trend, the average maximum temperature has no trend in winter and the rest of seasons have decreasing trend and average temperature only in spring has trend. Monthly temperature changes show that the average minimum temperature in January, July, August, September, October and December have a decreasing trend and other months have no trend. The average maximum temperature in the months of January, February, June, July, August September October and December is in a decreasing trend. The average temperature also has decreasing trend only in two months of July and September Analysis of annual, seasonal and monthly rainfall changes show that they have negative trend in warmer months.
 

Discussion

Nowadays, the issue of climate change is one of the significant issues of climate research. Forecasting the climate change trend is important and necessary. Climate changes have provided the basis for the occurrence of entropy or irregularities in the climatic elements, especially temperature and precipitation.
 

Conclusion

Sepidan is one of the mountainous and cold regions in Fars affected by climate change, in general, the change in some parameters, such as temperature, has a decreasing trend, unlike many regions of the country. The average temperature, the average minimum temperature and the average maximum temperature show the decreasing trend This situation is caused by the altitude and mountainous nature of the region. Seasonal examination of temperature parameters at Sepidan shows the existence of a trend and lack of a trend in other seasons. So that the average minimum temperature in spring and summer has a decreasing trend and winter and autumn have no trend. The average maximum temperature also has no trend in winter and spring, summer and autumn has a decreasing trend. The average temperature has a decreasing trend in spring and other without a trend. In terms of seasonal temperature changes, the biggest decreasing to spring. Examining the Kendall and critical statistics in relation to monthly temperature changes shows that the average minimum temperature in January, July, August, September has a decreasing trend and other months have no trend. The average maximum temperature in the months of January, February, June, July, August, September has a decreasing trend and there is no trend in other months. The average temperature in two months of July and September has a decreasing trend and there is no trend in the other months. It is worth noting that the most of decreasing trend in the temperature parameters is related to September. The study of the monthly changes in precipitation shows a decreasing trend in the hot months of the year and the lack of a trend in other months. The largest decrease with a statistic (T) of -0.66 belong to June and there isn't any trend in seasonal precipitation.
 
Acknowledgments
We would like to thank the Statistics and Information Center of the Meteorological Organization and the Meteorological Research Institute for providing the data of Sepidan station.