Nature Geoscience 5, 911–917 (2012); published online 25 November 2012.

In the print version of this Article originally published, the present address for Toshitsugu Yamazaki was erroneously omitted. It is as follows: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan. This is correct in the PDF and HTML versions.