Heavy Pollution Suppresses Light Rain in China
Over the past decades, precipitation in China has generally increased in the south and decreased in the north. In addition to this prominent trend, known as the south flood north drought, an international team of scientists, led by researchers funded by a bilateral agreement on climate research between DOE and the China Ministry of Science and Technology, has now revealed that both the frequency and amount of light rain have also decreased significantly by 25% in eastern China (both north and south) in the last five decades. Concurrent with this highly spatially coherent trend in light rain is a dramatic increase in human-related pollutant emission. Based on satellite data and numerical modeling, the authors revealed that aerosols produced by air pollution can increase cloud droplet number concentrations and reduce droplet sizes. Because smaller cloud droplets are less efficient in the collision and coalescence processes, anthropogenic aerosols delay and suppress raindrop formation.
Y. Qian, D. Gong, J. Fan, L.R. Leung, R. Bennartz, D. Chen, and W. Wang: Heavy Pollution Suppresses Light Rain in China: Observations and Modeling. Journal of Geophysical Research, DOI 10.1029/2008JD011575.