13 February 2018

The Changing Character of Rainfall in Eastern China, 1951-2007

Science

We developed a new technique called the Frontal Rain Event Detection Algorithm (FREDA) and created a daily catalog of all frontal rain events in East China during 1951-2007, quantified their attributes and classified all rainfall on each day as either frontal, resulting from large-scale convergence, or non-frontal, produced by local buoyancy, topography or typhoons. Using the daily catalog, we characterized changes in summer precipitation in terms of the frequency, mean latitude and intensity of frontal rain events.

Impact

The partition of rainfall into frontal and non-frontal components provides a framework for diagnosing the relative roles of global warming, aerosols and natural variability in historical rainfall variability, and informing models used to project future precipitation changes.

Summary

Our climatology shows that the East Asian summer monsoon consists of a series of coupled changes in frontal rain event frequency, latitude, and daily intensity.  Furthermore, decadal changes in the amount and distribution of rainfall in East China are overwhelmingly due to changes in frontal rainfall, as non-frontal rainfall exhibits no trend. We attribute the “South Flood-North Drought” pattern observed beginning in the 1980s to changes in the frequency of frontal rain events, while the years 1994-2007 witnessed an uptake in event daily intensity relative to the rest of the study years.  This particular signature may reflect the relative impacts of global warming, aerosol loading and natural variability of regional rainfall, potentially via shifting the East Asian jet stream. 

Contact
Inez Fung
University of California - Berkeley
Publications
Liu, W. "Changing Character of Rainfall in Eastern China, 1951–2007." Proceedings of the National Academy of Sciences 201715386 (2018). [10.1073/pnas.1715386115].