Asal Falak, Reza Boran, Farideh Asadian,
Volume 21, Issue 62 (9-2021)
Abstract
This study aimed to investigate the temporal-spatial and synoptic features of thunderstorms in southwest of Iran (Khuzestan, Chaharmahal & Bakhtiari and Kohkiluyeh & Boyerahmad Provinces) It was compiled using volatility indices during the period 1985-2015. Results of Frequency Analysis of Thunderstorms at Dezful Station with 479 cases the highest frequency and Ramhormes with 252 days had the lowest frequency. In terms of seasonal distribution, spring was the most abundant with 39%. On a monthly basis, April had the lowest frequency with 21% and August with only 2 cases. In terms of thunderstorms the highest frequency of thunderstorms with no thunder was 21 percent. Synoptic analysis: Most of the time there is a nave (at level 500) or low pressure in the west of the region, east of the Mediterranean Sea with its tabs clockwise. From the Red Sea and the Persian Gulf, they entered the south, southwest, and west of Iran On the other hand, the high-pressure system on the Gulf of Aden in the east of the region is round in the clock It has injected moisture, especially at a level of 850 millibars. Interaction between the two systems over the course of the day, It has injected moisture from three sources of the Mediterranean Sea, the Red Sea and then the Persian Gulf into the rising systems of the region. The low-pressure counterclockwise movement of the eastern Mediterranean, Along with the high-altitude clock movement over the Gulf of Aden, it has injected moisture at levels of 850 to 700 degrees.
Mina Daneshvar, Dr Hassan Lashkari, Reza Borna,
Volume 25, Issue 0 (3-2026)
Abstract
Thunderstorms are considered compound atmospheric hazards, as they simultaneously involve several hazardous phenomena such as lightning, strong and gusty winds, intense convective rainfall, and torrential precipitation. Consequently, these storms are often associated with damage to urban infrastructure and environmental impacts. The objective of this study is to analyze the spatiotemporal distribution of thunderstorms across Tehran Province over a 33‑year period corresponding to the last three solar cycles. Owing to its distinctive topographic conditions and geographical location, Tehran Province is regarded as one of the regions prone to the occurrence of this phenomenon. The data used in this research include lightning reports recorded at nine synoptic stations in Tehran Province during the period 1986–2019. To improve the accuracy of thunderstorm system identification, only events that were simultaneously recorded at a minimum of two stations and during at least two six‑hour observation intervals were selected. The analyses were conducted at monthly, seasonal, and annual scales using statistical and spatiotemporal approaches within the framework of three 11‑year solar cycles. Zoning maps of thunderstorm occurrence frequency were also produced for solar cycle 24 using a larger number of stations with an appropriate spatial distribution. The results indicate that the highest frequency of thunderstorms occurs during the spring season, particularly in May. Despite the passage of most precipitation systems during autumn and winter, the lowest thunderstorm activity was observed in winter. Approximately 70% of the systems had a one‑day duration, and more than half of the events were reported only twice per day. Spatially, Imam Khomeini station and, at a regional scale, the southwestern part of the province in most seasons and the northeastern part during summer exhibited the highest frequencies. Considering the economic and infrastructural impacts as well as aviation‑related hazards, the development of thunderstorm warning systems in Tehran Province appears to be essential.
