Definition of Monsoon Indices

1. Webster-Yang monsoon index (U850-U200 averaged over 0-20ºN, 40ºE-110ºE)

Reference:
Webster, P. J., and S. Yang, 1992: Monsoon and ENSO: Selectively interactive systems. Quart. J. Roy. Meteor. Soc., 118, 877-926.

2. Australian monsoon index (U850 averaged over 2.5ºS-15ºS, 110ºE-150ºE)

Reference:
Hung, C.-W., and M. Yanai, 2004: Factors contributing to the onset of the Australian summer monsoon. Quart. J. Roy. Meteor. Soc., 130, 739-758.

3. South Asia monsoon index (V850-V200 averaged over 10ºN -30ºN, 70ºE-110ºE)

Reference:
Goswami, B. N., B. Krishnamurthy, and H. Annamalai, 1999: A broad-scale circulation index for interannual variability of the Indian summer monsoon. Quart. J. Roy.. Meteorol. Soc., 125, 611-633.

4. Dynamic Indian monsoon index (U850 (5ºN -15ºN, 40ºE-80ºE) – U850 (20ºN -30ºN, 70ºE-90ºE)

Reference:
Wang, B., and Z. Fan, 1999: Choice of south Asian summer monsoon indices. Bull. Amer. Meteor. Soc., 80, 629-638.

5. East Asia-WNP monsoon index (U850 (5ºN -15ºN, 90ºE-130ºE) – U850 (20ºN -30ºN, 110ºE-140ºE)

Reference:
Wang, B., Zhiwei Wu, Jianping Li, Jian Liu, Chih-Pei Chang, Yihui Ding, and Guoxiong Wu, 2008: How to Measure the Strength of the East Asian Summer Monsoon. To be published on Journal of Climate.