The tenth IMSC, Beijing, China, 2007 - International Meetings on ...

A novel multi-scale analysis method, Empirical Mode Decomposition (EMD),is used to
analysis the annual streamflow of the Yangtze River at the three Gorges Dam in <strong>China</strong>. <strong>The</strong>
results shows that:(1) <strong>The</strong> annual streamflow of the Yangtze River at the three Gorges Dam
can be decomposed into four timescales quasi-periodic oscillations including a 3 year signal, a
7 year signal, a 13 year signal and a 54 year signal, as well as a trend. With each contributing
ration of the quasi-periodicity discussed, the 13 year and the 54 year timescale oscillation is
the most prominent.(2)Using the model for annual streamflow of the Yangtzs river at the three
gorges dam based on EMD, the predictions of streamflow from 2001 to 2004 are tried and
show good effects. <strong>The</strong> relative errors of model 1 and model 2 are less than 12.5% and 2.4%
respectively.(3)Five years prediction in advance of annual streamflow for the Yangtze River at
the three Gorges Dam shows that the annual streamflow will be less in the future two years,
then rise again in the third and forth year, up to the year 2012 the greater streamflow
comparing to that in 1998 will probably occur. <strong>The</strong> results of the study provide a valuable
information for operating and managing the Three Gorges hydro-power station.
Climate Change in the Siberian High and Its Relationship to the East-Asian Monsoon
Hong-xing Cao
Chinese Academy of Meteorological sciences
caohx@sina.com
Hai-yan Yu
<strong>Beijing</strong> Bureau of Metrology
Ju-zhi Ji
Harbin Bureau of Meteorology
<strong>The</strong> Siberian high is a large scale system of the Northern hemispheric circulation, which
dominants other systems, such as the circulation over the Eurasia, the East-Asian Monsoon,
the Meiyu over the Yangtze River. <strong>The</strong> study of climate change in the Siberian High has been
carried out and presented in this paper.In order to understanding the interannual to
interdecadal variations of the Siberian high, the index I of the Siberian high for 1873―2000
was calculated using the NCEP/NCAR reanalysis data, the index I is a mean of the sea level
pressure (SLP) for all network points covering 40―55°N, 90E―110°E.<strong>The</strong> climate change in
the Siberian high in winter was investigated. Its linear trend is almost at zero, it means the
variation in the Siberian high in winter oscillated around an average since 1873. <strong>The</strong>re were
three oscillations during 1873 to 2000, the averaged oscillation period is about 40yr. <strong>The</strong>
minimum of the Siberian index I during 1873 to 2000 is 1025.1 hPa in 1917, but the maximum
is 1038.1 hPa in 1967. <strong>The</strong>re were two periods with a low pressure during 1913―1922 and
1988―1998 respectively. But there was one period with a high pressure during 1966―1974,
but the pressure values are not so high. <strong>The</strong> interdecadal variation was investigated too. <strong>The</strong>
result shows that the interdecadal variation of the Siberian index is significant.In order to model
the climate change in the Siberian high in winter, a new approach of time series analysis is
carried out, it is called a data-based self-memoried (DASM) model. Self-memoried principle of
dynamic system is briefly described, then the DASM model is presented as well. <strong>The</strong> DASM
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