Aimed at improving understanding of the variability and linkage of rainfall over North China and southwest Western Australia (SWWA), the Sino-Australian bilateral climate change program “Rainfall and Climate change in Australia and China” was endorsed in 2007. In the past two years, with the joint efforts of the Chinese principal investigator Prof. Jianping Li, one of the team members Juan Feng (both from the Institute of Atmospheric Physics, Chinese Academy of Sciences), and the Australian principal investigator Dr. Yun Li (Australian Commonwealth Scientific and Industrial Research Organization (CSIRO)), the causes of the decreased precipitation during rainy season of the SWWA are revealed. This research is specially reported by CSIRO recently, with the highlight “CSIRO and Chinese scientists have developed a new climatic index which provides an answer to a riddle that has puzzled researchers for decades: ‘Why has south-west Western Australia experienced dramatic declines in rainfall since the 1970s?’”
SWWA locates in the southwest corner of the Western Australia. It is the political, economic, cultural, education, and tourism center of the Western Australia, and also the wine region and wheat belt of the Western Australia. The observed rainy season precipitation of the SWWA has significantly declined since 1950s. The reduction in winter rainfall resulted in an even sharper fall in the stream flow in the southwestern Australia and heavily impacted the water resources in the state. The attribution of rainfall variation becomes the focus of many researches and has drawn much attention.
In the newly published paper in the “Journal of Climate”, they put forward a new concept of the southwest Australian monsoon-like circulation (SWAC), and demonstrated that the circulation nature in the southwest Australia exhibit subtropical monsoonal characteristics. Based on this concept, they defined an index to depict the strength of the circulation, and explored the important role of the circulation on the SWWA rainfall. Results implied that the weakened trend in the SWAC is the possible contributor to the long term rainfall decrease over the SWWA. The discovery of the monsoon-like SWAC provides a new tool to further understand the rainfall variability of the SWWA, and offers a potential perspective for the study of rainfall variation attributions, estimating the skills of the climate models, and further rainfall projection over SWWA.
According to Dr Ian Foster from the Department of Agriculture and Food WA, the department will adopt the new index to help forecast seasonal rainfall and to assist farmers with agricultural management decisions such as, which crops to plant and when.
Linkage:
http://www.csiro.au/news/New-climate-index-solves-south-west-WA-rainfall-riddle.html
http://journals.ametsoc.org/doi/abs/10.1175/2009JCLI2837.1
