Identification of Iran’s precipitation regimes

Abstract

In the present study, the precipitation regime (PR) was investigated as a feature of the structure of Iran’s climate and its relationship with spatial-topographic variables and its spatial pattern. Spatial patterns of the indices of the PR used in the present study exhibited significant agreement in illustrating the diverse PRs of Iran. The diversity of spatial factors provided the spatial diversity of precipitation characteristics, including PR. Harmonic analysis (HA) results confirmed the country’s diverse PRs, which were attributed to different mechanisms affecting Iran’s precipitation patterns throughout the year. Using multiple methods in the present study, four PRs were identified. According to the methods used, the increase in precipitation in each location was associated with a reduction in the month-to-month difference in precipitation and an enhancement in the uniform distribution of precipitation. All indices indicated that the northern regions of Iran, including the Iranian coast of the Caspian Sea (ICCS), exhibited a uniform PR. The northwestern (NWI) and southeastern (SEI) regions displayed a relatively uniform regime, while the remaining parts of the country experienced a seasonal regime characterized by a longer dry season. Furthermore, there was a notable correlation between the PR and latitude, particularly from approximately 35 degrees northward. Moreover, there was a notable correlation between the PR and latitude, particularly from approximately 35 degrees northward. As for the southern regions of the country, beyond the latitude of 35 degrees, the spatial distribution of PRs was influenced not only by latitude but also by other variables such as longitude, altitude, and the shape and length of the Persian Gulf coast adjacent to the eastern deserts. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.