Changes in the mixed layer of the Atlantic Ocean significantly drive the Atlantic Multidecadal Variability (AMV).
A recent study has revealed that the turbulent movement of the upper layer of the Atlantic Ocean’s tropics plays a vital role in shaping long-term climate patterns globally.
Researchers have identified that alterations in the ocean’s mixed layer—the uppermost area where warm surface waters mix with cooler depths due to wind and waves—are the main factor behind the climate phenomenon known as Atlantic Multidecadal Variability (AMV) occurring in the tropical regions.
The AMV significantly impacts the global climate, affecting weather systems from North America to Europe and Africa. This includes variations in hurricane activity in the Caribbean and changes in rainfall patterns in the Sahel region.
Dr. Balaji Senapati, the primary author of this study from the University of Reading, stated: “Previously, it was thought that shifts in heat exchange between the ocean and the atmosphere were responsible for the climate patterns impacting various regions worldwide. Our study offers a new perspective, indicating that the depth of the mixed layer is crucial in global climate variability.”
“This research enhances our understanding of Atlantic climate variability and underscores the intricate relationship between the ocean and atmosphere in influencing our planet’s climate. Insights into natural climate variability are becoming increasingly important for creating effective strategies to tackle climate change challenges.”
Enhancements in Forecasting
Published this month in Geophysical Research Letters, the study observed that when the North Atlantic region outside the tropics is warmer than usual, the trade winds weaken. This leads to a shallower mixed layer in the ocean, particularly during summer, as the sun’s energy warms a thinner layer of water, resulting in greater warming of the tropical Atlantic.
This creates a feedback mechanism: warmer waters in the Northern Atlantic weaken the trade winds, which in turn leads to a shallower mixed layer and additional warming in the tropics. Conversely, when the AMV transitions to its cooler phase, the process inverts, leading to cooler temperatures throughout the Atlantic.
The implications of these findings are crucial for climate modeling and long-term predictions. Many existing climate models may not accurately capture these upper-ocean dynamics, which could result in inaccurate predictions regarding the AMV and its global effects. By integrating this new understanding of ocean mixing into climate models, scientists aim to enhance their capacity to forecast long-term climate patterns and their consequent impacts on global weather systems.