East Asia and Western Pacific METEOROLOGY AND CLIMATE

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layers of the earth's crust) should include information of monthly averaged
circulation in the coming 6-11 months. The theoretical predictability on
monthly averaged circulation should be 6-11 months {chou, 1986) (1) . But
the difficulty is that no sufficient 3-dimensional data in the uppermost layers
of the earth's crust can be used. Fortunately, the 3—dimensional data
can be derived from general circulation anomalies in previous integration.
Therefore, we can use this circulation instead of the 3—dimensional data.
Nowadays, the routine long-range forecast performed with synoptic methods
or statistical methods is mainly concerned with the evolution theory of
general circulation. In these works, it is found that the teleconnection of
general circulation exists not only in space, but also in time. Some theories
have been suggested to explain the spatial teleconnection, but little attempt
is being made to investigate the temporal teleconnection, though the study
is of great significance for simulating the atmospheric general circulation
and predicting the climate numerically. In this paper, we shall introduce
some preliminary researches in this area, which consist of some unpublished
works of the author and his cooperators. Considering the limited space of
the paper, we shall give only a simple summary.
2. Analogous Rhythm Phenomenon
When atmospheric or oceanic variables are analyzed, a close asychronous
connection with a large time phase difference can be found. The relation is
very helpful for a forecaster to ensure the validity of the forecasts at the valid
time. Therefore, a lot of research has been carried out. However, some of
these relations presented are nothing but wrong ones due to sample error.
Thus the problem becomes complicated.
The original concepts for solving this problem can be traced back to
1920's. Mylbralovsk found a kind of temporal teleconnection for some
weather phenomena by analyzing daily surface weather maps in the USSR.
This teleconnection has a quasi—periodic time interval (90 days or 150
days), and he called it ''rhythm". The forecast accuracy with rhythm is fairly
high, between 65% and 80%. The difficulty is that the condition for beginning
the rhythm is so strict that few cases can be found during a month
(Wang and Zhao, 1.987) (13) ,. Of course, this cannot meet the need of prediction.
Wang (1984) (12) defined the /'rhythm'' as the time connection in the
atmosphere with a certain period (especially, quasi-semiannual interval),
He emphasized that the rhythm appears only in a fixed season and did not
repeat continuously, and no second phenomenon can be analyzed from the