Stratosphere–troposphere interactions and teleconnections associated with Iran’s winter warming in January 2024

Abstract January 2024 represented an extreme manifestation of the long-term winter warming trend in Iran, characterized by widespread warmth and dryness. During 14–15 January 2024, surface temperatures exceeded climatological means by up to ~ 4 °C, accompanied by reduced mid-tropospheric humidity and below-average precipitation across much of the country, indicating enhanced drought conditions. Synoptic analyses revealed a weakened and eastward-displaced Siberian High, negative sea-level pressure anomalies over northern Eurasia, and a pronounced mid-tropospheric ridge over Iran. At upper levels, strengthening and eastward displacement of the subtropical jet, together with a reversal of 10-hPa zonal winds, confirmed the occurrence of a major split-type Sudden Stratospheric Warming (SSW). The resulting polar vortex split promoted large-scale subsidence and reduced cold-air advection over Iran, leading to adiabatic warming and suppressed precipitation. Statistical analyses further indicate that tropical–extratropical interactions, particularly the Indian Ocean Dipole and the El Niño–Southern Oscillation, modulated the regional temperature response. Overall, this event demonstrates that warm-side surface responses following SSWs constitute an important but underexplored component of winter climate variability over West Asia, capable of amplifying ongoing regional warming and producing contrasting winter anomalies across Eurasia.