Wang, B. and Z. Fan, 1999: Choice of South Asian summer monsoon indices. Bull. Amer. Meteor. Soc., 80, 629-638.
Wang, B., R. Wu, K.-M. Lau, 2001: Interannual variability of Asian summer monsoon: Contrast between the Indian and western North Pacific-East Asian monsoons. J. Climate, 14, 4073-4090.
WYM Index = U850(40-110E,EQ-20N)-U200(40-110E,EQ-20N)
Webster, P. J. and S. Yang, 1992: Monsoon and ENSO: Selectively interactive systems. Quart. J. Roy. Meteor. Soc., 118, 877-926.
AUSM Index = U850(110-130E,15S-5S)
Kajikawa, Y., B. Wang and J. Yang, 2010: A multi-time scale Australian monsoon index, Int. J. Climatol, doi: 10.1002/joc.1955. early veiw online
The definition of all four monsoon indices is based on convection ceters related with
monsoonal rainfall during boreal summer and winter respectively.