A method for identifying warm fronts in Eurasia

Abstract Warm fronts often trigger significant weather changes, which play a role in numerous extreme weather incidents. Therefore, it is crucial to understand the location and characteristics of warm fronts to accurately forecast weather changes. This paper proposes a new objective method for identifying warm fronts in the Eurasia region using ERA-5 hourly reanalysis data. The method uses the appropriate thermal front parameter and warm advection threshold to identify the potential warm frontal zone, then determines the corresponding warm boundary according to the predominant wind direction within the frontal zone, and finally locates the warm front line along the warm boundary. By analyzing objective warm fronts in different weather processes, the strong correlation with weather systems and meteorological elements substantiates the effectiveness of the method. The substantial agreement with between objective warm fronts and manual identified ones further solidifies the reliability of the method. Furthermore, this method is applied to the long-term datasets covering Eurasia, enabling an exploration of the climatological characteristics of warm fronts in the region. The study reveals distinct seasonal patterns in warm front frequency, with the highest frequency occurring during winter and the lowest during summer. Warm fronts are notably active in Europe, the Siberian Plain, the Northeast China Plain extending to the Western Pacific during winter, spring and autumn. The dataset of warm fronts produced by this method proves valuable for climate change research.