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Zhao, Tianliang (2005): Normalmodenanalyse der Struktureigenschaften des asiatischen Sommermonsuns. Dissertation, LMU München: Fakultät für Physik



This thesis is about normal mode analysis on multi-scale characteristics of Asian summer monsoons. In this study a new concept of utilizing generalized normal mode initialization (NMI) is introduced for climatic analysis and diagnosis. For the actual constitution of normal modes (NMs)in this study, a two layer shallow water model was selected. We used the 17 year-atmospheric data to construct the basic state with the summer mean over those 17 years and to define the actual anomalies of the special summers relative to the climatic mean. The highlight in this study about normal mode analysis of Asian Summer Monsoons is that for the first time the following were considered with the instability of the 3-D basic state: 1) the nonlinear dynamic balancing of NMI, 2) the effects of hard orography (not only quasi-linear effects of vorticity and divergence), 3) actual anomalies of special episodes relative to a climatic mean and 4) the normal mode group with a specific range of oscillation frequencies. The NMs and NMI were conducted in two experiment-groups: 1)impacts of SST-anomalies with ENSO on Asian summer monsoons and 2)interannual variability of Meiyu and connections to multi-scale oscillations of Asian summer monsoons and yielded the interesting conclusions on Asian monsoon climate. The important insight from this thesis is that MNs and NMI, which have been used in the numerical weather forecast, were successfully applied in climatic analysis of Asian summer monsoons. Compared with the other methods, NMs and NMI have two advantages: 1) the atmospheric circulation structures in different time scales can be identified with normal mode groups giving distinctive signals, and 2) the impacts of various physical processes on the atmospheric circulation or climate change can be detected from the complement of the actual atmosphere to the model solution.