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In this paper, the variations of the mean flow, the E-P flux and its divergence of planetary waves in the process of the formation, maintenance and collapse of the blocking situation in the second half of February, 1979 are analysed with the transformed Eulerian mean-motion equations.Analysed results show that because the basic flow changes from the easterly into the westerly in the lower troposphere at high latitudes, the planetary wave for wavenumber 2 strongly propagates upwards, and because of the interaction between the upward propagating planetary wave and the basic flow, the westerty is weakened and approaches to the resonant flow of wavenumber 2 in the middle and upper troposphere (then, in the lower and middle Stratosphere). This may cause the anomalous amplification of planetary wave for wavenumber 2, and moreover make the mean flow change from the westerly into the easterly in the lower and middle stratosphere, following the upper troposphere. Therefore, the blocking situation can be formed a
In this paper, the variations of the mean flow, the EP flux and its divergence of planetary waves in the process of the formation, maintenance and collapse of the blocking situation in the second half of February, 1979 are analyzed with the transformed Eulerian mean- motion equations. An analysis result show that because the basic flow changes from the easterly into the westerly in the lower troposphere at high latitudes, the planetary wave for wavenumber 2 strongly propagates upwards, and because of the interaction between the upward propagating planetary wave and the basic flow, the westerty is weakened and approaches to the resonant flow of wavenumber 2 in the middle and upper troposphere (then, in the lower and middle Stratosphere). This may cause the anomalous amplification of planetary waves for wavenumber 2, and moreover make the mean flow change from the westerly into the easterly in the lower and middle stratosphere, following the upper troposphere. Thus, the blocking situatiation on can be formed a