Analysis of precipitation variation in the northern strip of Iran

The present study aimed at studying the spatial–temporal behavior of precipitation received over a long period of time in the northern strip in Iran. To this end, the available data related to the precipitation in the 50 years (1957–2007) were extracted from APHRODITE with a spatial resolution of 0.25° × 0.25°. Some statistical analyses such as dispersion statistics and the analysis of trend were run on the extracted data to obtain the precipitation changes in a decade, using MATLAB software. The results of the analyses showed that the precipitation changes in decade in the northern strip in Iran followed a high clustering pattern due to the physiography of the region, convection and the influence of weather systems, and over time, precipitation is concentrated in this region of the north of Iran. Statistical analyses showed that precipitation pattern had a severe disorder. The simulation of the precipitation density function also showed a decrease in precipitation variance and a sharpening of the Gaussian function, indicating the absence of constant precipitation conditions in the northern strip of the country. Moreover, the assessment of trends through non-parametric method showed that the annual precipitation has a decreasing trend in the region. Analysis of the daily precipitation concentration demonstrated a widespread distribution, and, confirmed the irregularity and inequality of daily precipitation across the northern strip of Iran.