Asian Summer Monsoon Index
Kawamura, R., 1998: J. Meteor. Soc. Japan, vol.76, 1009-1027.
To investigate the interannual variability of the South Asian summer monsoon system, a useful broad-scale monsoon circulation index is proposed by Kawamura (1998). This monsoon index is defined as the meridional difference in area-averaged upper-tropospheric (200-500 hPa) thickness between the Tibetan Plateau (50-100E, 20-40N) and the Indian Ocean (50-100E, 0-20N) regions, which is termed the meridional thermal gradient (MTG) index by Miyakoda et al. (2003)*. They confirm its usefulness as well as Webster and Yang's (1992) index.
*Miyakoda et al., 2003: J. Meteor. Soc. Japan, 81, 1015-1039.
The following text file is the time series of the MTG index based on two reanalysis data (NCEP and ERA40). JJAS, JJ and AS imply the mean values of June-September, June-July, and August-September, respectively. The anomaly is relative to the 1971-2000 average.
MTG Index (text file)
1) Kawamura, R. (1998): A possible mechanism of the Asian summer monsoon-ENSO coupling.[Abstract] J. Meteor. Soc. Japan, 76, 1009-1027.
2) Kawamura, R., T. Matsuura, and S. Iizuka (2001a): Role of equatorially asymmetric sea surface temperature anomalies in the Indian Ocean in the Asian summer monsoon and El Nino-Southern Oscillation coupling.[Abstract] J. Geophys. Res., 106, 4681-4693.
3) Kawamura, R., T. Matsuura, and S. Iizuka (2001b): Interannual atmosphere-ocean variations in the tropical western North Pacific relevant to the Asian summer monsoon-ENSO coupling. J. Meteor. Soc. Japan, 79, 883-898.
4) Kawamura, R., T. Matsuura, and S. Iizuka (2003): Equatorially symmetric impact of the El Nino-Southern Oscillation on the South Asian summer monsoon system.[PDF4.3MB] J. Meteor. Soc. Japan, 81, 1329-1352.
5) Kawamura, R., H. Aruga, T. Matsuura, and S. Iizuka (2004): Two different regimes of anomalous Walker circulation over the Indian and Pacific Oceans before and after the late 1970s.[PDF2.9MB] Earth's Climate: The Ocean-Atmosphere interaction, C. Wang et al., Eds., Geophys. Monogr., 147, in press.
6) Kawamura, R., R. Suppiah, M. A. Collier, and H. B. Gordon (2004): Lagged relationships between ENSO and the Asian summer monsoon in the CSIRO coupled model.[PDF222KB] Geophys. Res. Lett., 31, L23205, doi:10.1029/2004GL021411.