Trend and stationarity analysis of climatic variables are essential for understanding climate variability and provide useful information about the vulnerability and future changes, especially in arid and semi-arid regions. In this study, various climatic zones of Iran were investigated to assess the relationship between the trend and the stationarity of the climatic variables. The Mann-Kendall test was considered to identify the trend, while the trend free pre-whitening approach was applied for eliminating serial correlation from the time-series. Meanwhile, time series stationarity was tested by Dickey-Fuller and Kwiatkowski-Phillips-Schmidt-Shin tests. The results indicated an increasing trend for mean air temperature series at most of the stations over various climatic zones, however, after eliminating the serial correlation factor, this increasing trend changes to an insignificant decreasing trend at a 95% confidence level. The seasonal mean air temperature trend suggested a significant increase in the majority of the stations. The mean air temperature increased more in northwest towards central parts of Iran that mostly located in arid and semiarid climatic zones. Precipitation trend reveals an insignificant downward trend in most of the series over various climatic zones; furthermore, most of the stations follow a decreasing trend for seasonal precipitation. Furthermore, spatial patterns of trend and seasonality of precipitation and mean air temperature showed that the northwest parts of Iran and margin areas of the Caspian Sea are more vulnerable to the changing climate with respect to the precipitation shortfalls and warming. Stationarity analysis indicated that the stationarity of climatic series influences on their trend; so that, the series which have significant trends are not static. The findings of this investigation can help planners and policy-makers in various fields related to climatic issues, implementing better management and planning strategies to adapt to climate change and variability over Iran.

中文翻译：

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伊朗盛行干旱和半干旱气候区气候记录的非平稳性和自相关性对时空趋势和季节性分析的影响

气候变量的趋势和平稳性分析对于理解气候变率和提供有关脆弱性和未来变化的有用信息至关重要，尤其是在干旱和半干旱地区。在这项研究中，调查了伊朗的各个气候带，以评估趋势与气候变量平稳性之间的关系。Mann-Kendall 检验被认为是识别趋势，而无趋势预白化方法被用于从时间序列中消除序列相关性。同时，时间序列平稳性通过 Dickey-Fuller 和 Kwiatkowski-Phillips-Schmidt-Shin 检验进行检验。结果表明，在不同气候带上，大多数站点的平均气温序列有增加的趋势，但在消除序列相关因子后，在 95% 的置信水平下，这种上升趋势变为微不足道的下降趋势。季节性平均气温趋势表明大多数站点都有显着增加。西北向伊朗中部地区平均气温升高更多，主要位于干旱和半干旱气候区。降水趋势在不同气候带的大部分序列中显示出不明显的下降趋势；此外，大多数站点的季节性降水呈下降趋势。此外，降水趋势和季节性以及平均气温的空间格局表明，伊朗西北部和里海边缘地区在降水不足和变暖方面更容易受到气候变化的影响。平稳性分析表明，气候序列的平稳性对其趋势有影响；因此，具有显着趋势的系列不是静态的。这项调查的结果可以帮助与气候问题相关的各个领域的规划者和决策者，实施更好的管理和规划战略，以适应伊朗的气候变化和变率。