Interannual variability of tropospheric waves in the tropics : a possible link with tropical cyclogenesis

Summer planetary-scale tropical wave activity at both the 200- and 850-mb levels is studied using wavenumber-frequency power spectral analysis and compared with tropical cyclone formation in the eastern North Pacific. The differences in the power distribution are compared between the average over 1977 and 1979 and that over 1978, 1983, and 1985. Tropical cyclogenesis was infrequent in the eastern North Pacific in 1977 and 1979, and was considerably above average in 1978, 1983, and 1985. The results indicate that for years with above-normal tropical cyclogenesis, the planetary-scale symmetric Rossby waves are more active than they are in the years with below normal cyclogenesis