Spatial and temporal analysis of monthly precipitation variations ‎in Golestan Province using fractal dimension

Self-similarity characteristic of climate variables provides the spatial and temporal analysis, using fractal dimension. Therefore, the application of fractal geometry in predicting the nature of many natural processes (e.g. rainfall) in several areas is of great importance. The purpose of this study is to determine and calculate the fractal dimension of wet and dry periods, interpret and evaluate the spatial characteristics of dry and wet periods over 40 rain gauge stations in Golestan Province. Toward this attempt, the box-counting method has been employed to determine the number of wet-dry months at one to nine months temporal scales and the calculation of fractal dimension. Then, the regression lines are used to estimate the corresponding fractal dimensions over rainy and non-rainy periods. As well as the severity and duration of wet-dry durations were presented over the study area. The results indicated that variations of rainy/non-rainy durations vary in a range of 11 percent. According to the results, the number of consecutive wet-dry months decreased in coarser time scales (months). The analysis of fractal dimension showed that the dry periods have a lower frequency. The fractal dimension values were considered to determine the variations of precipitation regime over studied stations. Also, the intensity of wet durations is higher in central and eastern parts of the study area, while the western part of the Golestan Province had experienced more persistent wet periods.