A Teleconnection between the Reduction of Rainfall in Southwest Western Australia and North China

Rainfall in both southwest Western Australia (SWWA) and North China (NC) has been declining substantially since the mid-1960s, which has led to a series of droughts in both regions since then. Using observed rainfall datasets in China and Australia and the NCEP reanalysis dataset during 1951–2008, it is found that the decline of SWWA rainfall occurs in early austral winter [May–July (MJJ)] while the reduction of NC rainfall is in late boreal summer [July–September (JAS)]. The relationship between SWWA MJJ rainfall and NC JAS rainfall during 1951–2008 is then examined, and it is found that a significant link exists between these two rainfall series with a correlation of 0.43 and this link remains after the data are detrended. In particular, this relationship accounts for up to 62% variance on interdecadal time scales, and seems to be driven by the poleward shift of the southern subtropical high ridge (SSHR) and the northern subtropical high ridge (NSHR) over longitudes 110°–150°E. The poleward shif...