[Climate Change]Detectable anthropogenic shift toward heavy precipitation over eastern China

To address climate change, detection and attribution studies of precipitation are essential. Nonetheless, the detection ofregional precipitation change has been a challenge, especially at regional scale. Whether anthropogenicclimate change is manifested through a detectable effect onEast Asian precipitation remains unknown.

The work recently published in Journal of Climate was the first attempt to investigate the changes in the distribution of the daily precipitation amount over China during the last five decades using observation data sets. Shuangmei Ma, Tinajun Zhou and their American and European collaborators applied the optimal fingerprinting detection and attribution method to assess the anthropogenic contribution to precipitation changes, based on the outputs of the CMIP5 models.

The results show thatanthropogenic forcing hashad a detectable and attributable influence on thedistribution of daily precipitation amounts over eastern China (EC) during the second half of the twentieth century. They also found evidences suggesting that the observed shiftfrom weak precipitation to intense precipitation isprimarily due to the contribution of greenhouse gas (GHG) forcing, withanthropogenic aerosol (AA) forcing offsetting some of the effects of the GHGforcing (Fig. 1).Under GHG-induced warming, increased atmosphericprecipitable water and enhanced land–sea thermalcontrast cause the water vapor transport to EC fromthe adjacent oceans via southerly and midlatitudewesterly winds to strengthen, thereby favoring heavierprecipitation over EC. However, the countering effects of surface cooling induced by anthropogenicaerosols meant that some of this enhanced transport iscancelled out by AA forcing.

Reference:

Ma, S., T. Zhou*, D. Stone, D. Polson, A. Dai, P. Stott, H. Storch, Y. Qian, C. Burke, P. Wu, L. Zou, and A. Ciavarella, 2017: Detectable anthropogenic shift toward heavy precipitation over eastern China. Journal of Climate, 30, 1381-1396, doi:10.1175/JCLI-D-16-0311.1

Fig. 1 Linear trends of precipitation amount during 1956–2005 for the bottom 35% light precipitation at left andtop 10% heavy precipitation at right averaged over EC. Black barsare for observations. Red, green, brown, orange, and green bars arefor MME of the ALL, ANT, GHG, AA, and NAT forcing simulations, respectively. Gray symbols represent different models.

Citation :Ma, S., T. Zhou*, D. Stone, D. Polson, A. Dai, P. Stott, H. Storch, Y. Qian, C. Burke, P. Wu, L. Zou, and A. Ciavarella, 2017: Detectable anthropogenic shift toward heavy precipitation over eastern China. Journal of Climate, 30, 1381-1396, doi:10.1175/JCLI-D-16-0311.1 http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0311.1