Analysis of climate data using statistical methods on west of the Caspian Sea

Abstract Long-term observational data are essential for detecting and understanding local, regional and global climate change. The goal of this paper is to consider climate data of west of the Caspian Sea for any trends in Annual means of 2m temperature and precipitation at the stations of Anzali, Rasht, Astara and Lahijan for 1956-2018 period. Some inconsistencies in the data were found. Our analysis and computations are done for Mean, maximum and minimum temperature, and precipitation. Using some statistical methods, such as Pearson and spearman correlation and Z-score, some analytical considerations are done. The precipitation has mostly a downward trend, strongest in Anzali, opposite to the general global trends that are mostly upward in areas of abundant precipitation, such as in the study area. The results of homogeneous test analysis of time series data showed strong (99% confidence level) non-homogeneity trends (confidence level of at least 95%).