Why has Australia been so dry?

Places in Australia have been experiencing a historic drought in the past century, with the fourth-warmest autumn on record, and rainfall totals below average for most of Australia.

Source: by Dr De-Li Liu

Surrounded by Ocean, why does Oceania stand out as the second driest continent of all? Will artificial rainfall be helpful to ease the drought? 

De-li Liu, Principal Research Scientist from DPI Agricultural, New South Wales Depart of Primary Industries, Adjunct Professor of Climate Change Research Centre in University of New South Wales has more.