Zhi Li, University of New South Wales, Climate Change Research Centre, Sydney, NSW, Australia, Matthew H England, Climate Change Research Centre UNSW and ARC Centre of Excellence for Climate System Science, Sydney, NSW, Australia, Sjoerd Groeskamp, Royal Netherlands Institute for Sea Research, Den Burg, Netherlands, Yiyong Luo, Ocean University of China, Physical Oceanography Laboratory/CIMST, Qingdao, China and Ivana Cerovecki, Scripps Institute of Oceanography, La Jolla, CA, United States