Nonlinear atmospheric variability in the winter northeast Pacific 3 associated with the Madden - Julian oscillation

8 [1] The Madden-Julian Oscillation (MJO), the primary 9 mode of large-scale intraseasonal variability in the tropics, 10 is known to relate to the mid-latitude atmospheric 11 variability. Using neural network techniques, a nonlinear 12 projection of the MJO onto the precipitation and 200-hPa 13 wind anomalies in the northeast Pacific during January– 14 March shows asymmetric atmospheric patterns associated 15 with different phases of the MJO. For precipitation, the 16 strength of the nonlinear effect to the linear effect was 0.94 17 (in terms of the squared anomalies and averaged over all 18 phases of the MJO), indicating strong nonlinearity, while for 19 the 200-hPa wind, the ratio was 0.55, indicating moderate 20 nonlinearity. In general, anomalous winds blowing from the 21 north or from land were associated with negative 22 precipitation anomalies, while winds from the south or 23 from the open ocean, with positive precipitation anomalies. 24 The nonlinear effects generally induced positive 25 precipitation anomalies during all phases of the MJO. 26 Citation: Jamet, C., and W. W. Hsieh (2005), Nonlinear 27 atmospheric variability in the winter northeast Pacific associated 28 with the Madden-Julian oscillation, Geophys. Res. Lett., 32, LXXXXX, doi:10.1029/2005GL023533. 30