East Asia and Western Pacific METEOROLOGY AND CLIMATE

517
ANALOGOUS RHYTHM PHENOMENON OF CLIMATIC
ANOMALIES ON A SEASONAL SCALE
Chou Ji~~fan
Department of Atmospheric Sciences,
Lanzhou University, Lanzhou, Gansu, 730001 .China
ABSTRACT
The study of analogous rhythm of climatic anomalies on a seasonal
scale is summarized in this paper. The objective and meaning
of this problem are also introduced. The analogous evolution
of monthly mean circulation is analysed with strict statistical
method and observational data of long time series by Huang, Gao
and the author recently. The results show that the analosous
rhythm exists significantly. Some research has been done on the
comprehensive interpretation of the physical mechanism of the
rhythm, such as Marchuk (1979), Musaelyan (1980) and Wang
(1984). Recently the dynamical mechanism of analogous rhythm
phenomenon is studied theoretically with a greatly simplified
air-sea coupled model by Huang and the author. The result is given
in this paper. In addition, the numerical simulations and various
sensitivity studies are made by a more sophisticated global
air—sea coupled dynamic—statistical model to simulate the analogous
rhythm phenomenon in the evolution of the monthly mean
circulation anomaly. The results not only prove the results of the
theoretical analysis, but also provide a basis for utilizing the model
further to do seasonal long-term numerical forecast.
L Introduction
It is well known that the theoretical limit of daily weather forecasting is