Atmospheric rivers convey water vapor from the tropics to the poles. They are important water sources to coastal areas like the west coast of North America. The Madden-Julian Oscillation is one of the phenomena in the tropics that can influence broadly. There are still many unanswered questions in understanding the activity of atmospheric rivers. For example, how does the Madden-Julian Oscillation affect the lifecycle of atmospheric rivers? What physical processes are involved in this connection?
Atmospheric rivers are often linked to high-risk weather events. It is very important to understand the activity of atmospheric rivers so that people can act in advance to reduce the damage. Results may potentially help to improve the forecast of atmospheric rivers. This study also provides a useful tool to understand the connection between atmospheric rivers and the Madden-Julian Oscillation in the context of climate change.
Atmospheric rivers are one of the important roles to balance the hydrological cycle. The team used a tracking algorithm to record the lifecycle of atmospheric rivers. Then, the changes in the lifecycle of the atmospheric river are compared in different phases of the Madden-Julian Oscillation (MJO). When the enhanced (suppressed) convection center is located over the Indian Ocean (western Pacific), more atmospheric rivers originate over eastern Asia and fewer occur over the subtropical northern Pacific. Opposite changes in the number and location of atmospheric rivers appear when the enhanced (suppressed) convection is over the western Pacific (Indian Ocean). Results indicate that the MJO can affect the whole lifecycle of atmospheric rivers including the origin, propagation, lifetime, and termination. Atmospheric rivers are more active during certain MJO phases, which can be explained by the changes in wind and geopotential height that respond to the MJO. These findings can help studies to better predict atmospheric river activity and understand how atmospheric rivers will change in the future.