Normalmodenanalyse der Struktureigenschaften des asiatischen Sommermonsuns

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.