VATIS UPDATE Article

A team of researchers from East China Normal University, China, University of Central Florida and Colorado State University, the United States, carried out precipitation observations in the Southern Hemisphere which indicated an apparent moistening pattern over the extratropics during the time period 1979 to 2013. To investigate the predominant forcing factor in triggering such an observed wetting climate pattern, precipitation responses to four climatic forcing factors, including Antarctic ozone, water vapor, sea surface temperature (SST), and carbon dioxide (CO2), were assessed quantitatively in sequence through an inductive approach.

Coupled time-space patterns between the observed austral extratropical precipitation and each climatic forcing factor were firstly diagnosed by using the maximum covariance analysis (MCA). With the derived time series from each coupled MCA modes, statistical relationships were established between extratropical precipitation variations and each climatic forcing factor by using the extreme learning machine. The research has been published in the Journal of Geophysical Research: Atmospheres.

Based on these established statistical relationships, sensitivity tests were conducted to estimate ­precipitation responses to each climatic forcing factor quantitatively. Quantified differential contribution with respect to those climatic forcing factors may explain why the observed austral extratropical moistening pattern is primarily driven by the Antarctic ozone depletion, while mildly modulated by the cooling effect of equatorial Pacific SST and the increased greenhouse gases, respectively.