How Saharan dust influences hurricane rainfall

The impact of Sahara Desert dust on hurricane formation and weather patterns in North America has been widely acknowledged, according to Science Daily. However, a recent study in Science Advances has shed light on a previously unknown relationship between hurricane rainfall and Saharan dust plumes.

Contrary to traditional beliefs that sea surface temperature and atmospheric humidity control hurricane precipitation, the research reveals that Sahara dust plays a surprising leading role. According to Dr. Yuan Wang, a corresponding author, and an assistant professor at the Stanford Doerr School of Sustainability, "Surprisingly, the leading factor controlling hurricane precipitation is not, as traditionally thought, sea surface temperature or humidity in the atmosphere. Instead, it's Sahara dust."

The consequences of this revelation can have varying effects on hurricane rainfall. While thick dust plumes can lead to heavier rainfall and potentially more destruction from landfalling storms, dust particles can also efficiently form ice clouds within a hurricane, resulting in more precipitation. On the other hand, dust is capable of blocking solar radiation and cooling sea surface temperatures surrounding a storm's core, thereby weakening the tropical cyclone.

To deepen our understanding, the study employed machine learning techniques using 19 years of meteorological data and satellite observations to predict hurricane rainfall. The results revealed that the level of dust optical depth, which measures the amount of light penetrating through a dusty plume, serves as a key predictor of rainfall. Interestingly, there is a boomerang-shaped relationship, where rainfall increases with dust optical depths ranging from 0.03 to 0.06 but sharply decreases thereafter. In other words, at high concentrations, dust transitions from enhancing rainfall to suppressing it.

While the study has shed light on the impact of Saharan dust on hurricane rainfall, several uncertainties remain. The decline in Saharan dust transport in the upcoming years and the potential increase in hurricane rainfall due to human-caused climate change raise important questions. Furthermore, the intricate relationships among Saharan dust, ocean temperatures, and hurricane formation, intensity, and precipitation are still not fully understood. Addressing these uncertainties is crucial to effectively prepare for and mitigate the impacts of climate change, as hurricanes have the potential to cause significant devastation.

Dr. Wang emphasizes the need to consider dust as a significant factor in conventional weather prediction methods, especially for hurricanes. Additionally, the study suggests that both microphysical enhancement, where dust particles facilitate ice cloud formation, and the radiative suppression effect, where dust shields the ocean surface from sunlight, play significant roles in determining rainfall patterns.

Collaborating authors from institutions like Western Michigan University, Purdue University, University of Utah, and California Institute of Technology have contributed to this comprehensive study. As we continue to explore the complex dynamics between Saharan dust, hurricanes, and climate change, a clearer understanding of these relationships will be vital in preparing for future extreme weather events.

Earlier SSP reported that a skeleton of one of world's oldest dinosaur was discovered after heavy rains in Brazil.