#South Korea #Pusan National University #Aerosols #Rainfall Patterns #Pusan

The Impact of Air Pollution on Rainfall in Southeast Asia

A significant study conducted by researchers at Pusan National University sheds light on the role of air pollution in altering rainfall dynamics across Southeast Asia. The research, spearheaded by Professor Kyong-Hwan Seo, underscores the influence of tiny airborne particles known as aerosols stemming from biomass burning, urban pollution, and industrial emissions. The findings suggest that escalating aerosol concentrations over the Maritime Continent not only intensify oceanic rainfall but also delay and suppress rainfall on land, contributing to a major shift in established precipitation patterns.

Understanding Aerosols and Their Effects

Aerosols are minuscule particles that float in the atmosphere, and their presence can dramatically affect weather phenomena. Their impact on rainfall begins with changes in atmospheric stability; high aerosol levels cool the land more significantly than the ocean. This cooling enhances low-level moisture convergence over the seas, resulting in heavier rainfall at sea and delaying the onset of rainfall on land until nighttime.

The research utilized a sophisticated 2-km-resolution atmospheric model alongside data from NASA's TRMM satellite and MERRA-2 reanalysis to simulate the interactions between aerosol concentrations and precipitation. The team observed these changes through various events, stressing that higher aerosol levels resulted in an ocean-dominant rainfall pattern, contrasting sharply with the earlier land-enhanced precipitation.

Key Findings and Implications

Professor Seo states, "As aerosol concentrations rise, the precipitation pattern shifts from a land-enhanced to an ocean-dominant one." The findings reveal an extraordinary increase of up to 50% in oceanic rainfall correlating with reduced land precipitation. This alteration signifies a notable increase in the sea-to-land rainfall ratio, a phenomenon newly recognized through the study's simulations and satellite observations.

The mechanics of this shift are primarily attributed to radiative effects; aerosols create a cooling effect over land compared to the warmer ocean, effectively stabilizing the atmosphere over the islands while maintaining a degree of instability at sea. Consequently, the planet experiences a delay in peak rainfall timings, with p.m. storms shifting to midnight peaks—a pattern emerging from reduced daytime heating coupled with evening build-up of moist static energy.

These dynamic alterations in rainfall timing and intensity carry practical implications for populations dependent on predictable weather patterns, especially in flood-prone urban areas like Jakarta and Manila. Improved forecasting models that account for aerosol-related changes can contribute to more proactive disaster management strategies, irrigation evaluations, and urban infrastructure planning, thereby reducing risks associated with extreme weather.

Broader Impacts on Climate Predictions

Beyond immediate urban development and management, these findings could revolutionize climate prediction methods across the region and potentially beyond. By incorporating aerosol impacts into climate models, researchers can refine predictions for significant weather events, including the Madden-Julian Oscillation (MJO), overall monsoons, and extreme rainfall instances—all crucial for areas that experience seasonal weather fluctuations influenced by various climatic systems.

In conclusion, this pivotal research from Pusan National University not only enhances our understanding of the nuanced interactions between air pollution and precipitation but also underscores the need for integrated approaches in climate forecasting that consider local aerosol dynamics. As global communities strive to adapt to climate variability and its repercussions, insights from this study may provide essential guidance for future water resource management, agricultural planning, and preparedness against weather extremes.

Reference

• - Title of original paper: "Aerosol effects on Maritime Continent precipitation: Oceanic intensification and land diurnal cycle delay."
• - Journal: npj Climate and Atmospheric Science.
• - DOI: 10.1038/s41612-025-01215-5