A groundbreaking study led by Qiuxiao Zhu and Dr. Huixin Li at Nanjing University of Information Science and Technology, alongside Dr. Shengping He from the University of Bergen, has unveiled new insights into the atmospheric dynamics driving compound hot drought events (CHDEs) in Northern East Asia (NEA). This research, published in Science China Earth Sciences, provides a detailed physical mechanism that links the Atlantic Multidecadal Oscillation (AMO) to significant interdecadal variations in the frequency and severity of these extreme climate phenomena.
Through extensive analysis of reanalysis datasets spanning from 1940 to 2022, combined with sophisticated Atlantic pacemaker experiments using the CESM1.1 model, the team identified critical temporal transitions in the intensity of July CHDEs over NEA. Two standout shifts were particularly notable: a marked reduction in the mid-1950s and a pronounced intensification beginning in the mid-1990s. These interdecadal alterations appear closely synchronized with phase changes in the AMO, a basin-wide sea surface temperature oscillation that profoundly influences Northern Hemisphere climate variability.
The AMO’s positive phase triggers a chain of atmospheric responses starting with anomalous warming across the North Atlantic Ocean. This warmth initiates Rossby wave trains that extend their influence across the Eurasian continent. The teleconnection effect manifests as a northward shift and amplification of the subtropical westerly jet stream, a fundamental driver of weather and climate patterns in the mid-latitudes. This jet intensification enhances the development of regional high-pressure systems across NEA, which in turn fosters strong descending, or subsiding, air flows.
Such descending motions are crucial because they suppress convective cloud formation, resulting in significant reductions in regional precipitation. The combination of suppressed rainfall and increased insolation exacerbates surface heating, thereby increasing land surface temperatures to levels conducive to hot drought occurrences. This atmospheric feedback loop effectively intensifies both the frequency and magnitude of CHDEs during AMO’s warm phase, highlighting the profound influence of ocean-atmosphere interactions on regional hydroclimate extremes.
Conversely, during the AMO’s negative phase, the North Atlantic cools anomalously, weakening these teleconnection patterns. The subtropical jet weakens and shifts southward, and regional anticyclonic pressure anomalies diminish. These conditions contribute to enhanced rainfall and relatively cooler temperatures over NEA, thus alleviating the severity and occurrence of CHDEs. This remarkable alternating pattern underscores the AMO’s critical role as a pacemaker for hydroclimatic variability in this geopolitically and ecologically sensitive region.
Importantly, the study leverages the CESM1.1 (Community Earth System Model version 1.1) through controlled Atlantic pacemaker experiments. By prescribing observed SST anomalies in the North Atlantic, the researchers could isolate and quantify the direct influences of AMO on extratropical atmospheric circulation and hydroclimate variability. This modeling approach provided robust evidence for the causal linkage between AMO-driven SST changes and CHDE modulation, thus offering predictive insight into future decadal drought risk under evolving climate dynamics.
These findings represent a significant advancement in our understanding of compound hot drought phenomena, where extreme heat and drought co-occur to exacerbate environmental and socio-economic impacts. With NEA being home to dense populations and crucial agricultural zones, the enhanced risk posed by AMO-positive phases necessitates improved anticipation and management strategies. The elucidation of these physical mechanisms enables refined decadal prediction systems and informs proactive disaster risk frameworks to mitigate the effects of these climatically driven extremes.
Beyond its regional focus, the study also contributes to the broader discourse on large-scale climate variability and its teleconnections. It illustrates the intricate links connecting distant oceanic basins—such as the North Atlantic—and continental climate extremes, showcasing the global nature of climate system interdependencies. By revealing how interdecadal ocean modes like the AMO modulate atmospheric circulations that shape terrestrial drought and heatwave patterns, this research underscores the urgency of integrating ocean-atmosphere coupling in climate models.
Given the increasing prevalence and severity of compound hot droughts worldwide driven by anthropogenic climate change, insights into natural variability and its modulation of extremes are invaluable. This study’s sophisticated coupling of observational and modeling techniques sets a methodological benchmark for future investigations into multidecadal climate drivers. In turn, this facilitates enhanced risk assessments aiding policy makers and stakeholders in harmony with ongoing climate adaptation and mitigation efforts.
The research further emphasizes the importance of sustained observational networks and climate reanalyses spanning multiple decades. Without such comprehensive datasets capturing historic climate fluctuations, uncovering the subtle interdecadal influences underpinning extreme events like CHDEs would remain elusive. The study’s temporal breadth spanning more than 80 years offers a rich platform for deciphering natural variability’s imprint amid the backdrop of evolving anthropogenic forcings.
In summary, the interdisciplinary collaboration between atmospheric scientists and climate modelers has culminated in a transformative understanding of how the Atlantic Multidecadal Oscillation shapes the climatology of Northern East Asia. By establishing a coherent mechanistic framework linking oceanic temperature oscillations to atmospheric teleconnections and regional drought-heat compound extremes, the study paves the way for improved climate predictions and adaptive strategies. These developments are pivotal in safeguarding vulnerable communities facing heightened climatic stress.
As the climate continues to change, elucidating the physical drivers behind extreme hydroclimatic events will remain a cornerstone of climate science. This work not only advances fundamental knowledge but also has practical implications for forecasting, disaster preparedness, and sustainable development. The AMO’s modulation of CHDEs in NEA offers a compelling example of the complex yet predictable interactions governing Earth’s climate and highlights the ever-growing need to incorporate such insights into future resilience planning.
Subject of Research: Interdecadal modulation of compound hot drought events by the Atlantic Multidecadal Oscillation in Northern East Asia
Article Title: How the AMO influences interdecadal variations of compound hot drought events in Northern East Asia
News Publication Date: 2025
Web References: DOI: 10.1007/s11430-025-1642-3
Image Credits: ©Science China Press
Keywords: Atlantic Multidecadal Oscillation, Compound hot drought events, Northern East Asia, Rossby wave trains, Subtropical westerly jet, Atmospheric teleconnection, Climate variability, CESM1.1, Hydroclimate extremes, Decadal prediction, Climate modeling, Drought risk management
