Climatology
Sirus Khodadadeh; Ali Mohammad Khorshiddoust; BEHROOZ SARISARRAF
Abstract
ABSTRACT
The relationship between Rossby wave breaking and heavy rainfall events in northwest Iran was examined on a synoptic scale. This study analyzes the potential vorticity (PV) at the 330 Kelvin potential temperature level. Severe rainfall systems in northwest Iran were identified for a 33-year ...
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ABSTRACT
The relationship between Rossby wave breaking and heavy rainfall events in northwest Iran was examined on a synoptic scale. This study analyzes the potential vorticity (PV) at the 330 Kelvin potential temperature level. Severe rainfall systems in northwest Iran were identified for a 33-year statistical period (1990-2024), leading to the identification of Rossby wave breaking events. A long-term climatological analysis of both anticyclonic and cyclonic Rossby wave breaking was conducted. Four patterns of Rossby wave breaking were identified for two types of breaking, in connection with severe rainfall occurrences in northwest Iran. The results indicate that the identified patterns exhibit the highest frequency of Rossby wave breaking events in spring and autumn, while winter and summer rainfall patterns show the lowest frequencies. The highest frequency of cyclonic wave breaking events (CWB) occurs in the months of Farvardin (March-April) and Ordibehesht (April-May), while the highest frequency of anticyclonic wave breaking events (AWB) occurs in the months of Mehr (September-October) and Aban (October-November). The analysis of potential vorticity streamers (2PVU) and their relationship with heavy rainfall events in the studied region shows a strong seasonal dependency between Rossby wave breaking that penetrates both latitude and longitude, contributing to or enhancing heavy rainfall in northwest Iran. Consequently, this research can provide a better understanding of synoptic and dynamical rainfall patterns and improve medium- to long-term weather forecasting in the country.
