Journal Article

Longer‐ and Slower‐Moving Contiguous Heatwaves Linked to El Niño

Huang, Ziwei, Wu, Sijia, Li, Xiang, Liu, Zhen, Wang, Xiaoyu, Luo, Ming

2024

Overview

Although it is known that the frequency and intensity of heatwaves are affected by the El Niño–Southern Oscillation (ENSO), unknown are the ENSO modulations on the moving properties (e.g., moving distance and speed) of spatiotemporally contiguous heatwaves. Here, we investigate the relationship between ENSO and the moving patterns of contiguous heatwaves. We show that contiguous heatwaves are likely more frequent, more persistent, and longer‐traveling, but slower‐moving during El Niño than La Niña episodes. The differences in the tropical contiguous heatwaves between El Niño and La Niña are influenced by persistent high‐pressure anomalies. During the following summers, El Niño can induce anomalous atmospheric circulation characterized by an intensified subsidence over the western North Pacific and ascending motion over the tropical Indian and Pacific Oceans. These features provide favorable conditions for the occurrence and maintenance of contiguous heatwaves. Plain Language Summary The El Niño–Southern Oscillation (ENSO) is among the strongest climate variation phenomena, which has important effects on the frequency and intensity of heatwaves across the globe. However, how ENSO influences the joint evolution behaviors of heatwaves at both temporal and spatial dimensions (e.g., moving patterns including traveling distance and moving speed) is not fully understood. Here, we first track the spatiotemporally contiguous heatwaves that occur simultaneously in adjacent regions or consecutively in neighboring days, and investigate their moving patterns over global land areas during 1961–2020. Then, we examine the relationship between the ENSO and the moving properties of these contiguous heatwaves. The results show that contiguous heatwaves during El Niño years not only tend to be more frequent and more persistent, but also travel longer distances and at slower moving speed, especially in tropics. This relationship is likely due to persistent high‐pressure anomalies caused by El Niño, which can intensify subsidence over the western North Pacific and ascendance over the tropical Indian and Pacific Oceans. This knowledge is crucial for improving our predictions about heatwaves and adapting their potential impacts. Key Points Contiguous heatwaves tend to be more frequent, more persistent, and longer‐traveling, but slower‐moving during El Niño than La Niña Differences in tropical contiguous heatwaves between El Niño and La Niña episodes are influenced by persistent high‐pressure anomalies El Niño intensifies contiguous heatwaves via inducing sinking over the western North Pacific (WNP) and rising over the tropical Indian Ocean

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Anomalies / Atmospheric circulation / Atmospheric circulation anomalies / Climate variations / Distance / El Nino / El Nino phenomena / El Nino-Southern Oscillation event / El Niño‐Southern Oscillation (ENSO) / Heat waves / Heatwaves / La Nina / longer‐lasting / longer‐traveling / Oceans / Pressure anomalies / slower‐moving / Southern Oscillation / spatiotemporally contiguous heatwaves / Subsidence / Tropical environments