Australian monsoon index

U850 averaged 5–15°S, 110–130°E (westerly > 0 = monsoon). Onset (ds.attrs['ausmi_onset']) is the first day from 1 Nov with AUSMI > 0 on the day and over the next 5 days, positive pentad means in ≥3 of the next 4 pentads, and a 4-pentad mean > 1 m/s (our reading of the paper's wording). — Kajikawa, Wang & Yang 2010, Int. J. Climatol. 30, 1114–1120, doi:10.1002/joc.1955