Abstract
The probabilities and entropies are calcurated based on the transition matrixes for eight types of the daily pressure patterns over Japan and the adjacent area. The transi tion process of the daily pressure patterns are so-called “Markov processes” and not but randam process. The results indicate the following characteristic features of daily pres sure patterns;
1) The transition pattern (the trasition probabilities and entropies) for the pressure patterns during 1941 to 1970 indicate that typhoon pattern (VI-Type) and summer weather pattern (V) mostly change to the same pattern. Trough pattern (II) shows higher multiplicity, while summer weather pattern (V) show lower diversity. Trough pattern (II) and migratory anticyclone pattern(III) are fundamental ones which appear throughout the year.
2) The transition pattern for every ten years (1941-1950, 1951-1960, and 1961 1970) show a similar to that of a whole thirty years period, 1941 1970. Quasi-stationary frontal pattern (IV) during 1951 to 1960 shows peculiar transitional characters.
3) The fourteen seasons proposed by Yoshino and Kai (1977) have the characteristic features of the transition patterns, as follows:
(Early spring): The transitions of pressure patterns have high diversity. (Spring): The cycle from II to III pattern is dominant. (Late spring): There are high entropies of each pattern indicating high diversity and this means that the various cycles are appeared in spring, in other words, they change to the different pattern in next season generally. (Early summer): The patterns of II, III and IV are dominant, and transfer randomly from one to another.
(Bai-u): The dominance of IV pattern is characteristic, and the V, III and II patterns are sometimes intercated in the IV pattern.
(Summer): The V pattern continues predominantly day by day.
The patterns of IT and III transfer from various patterns, and transfer only to the patterns of V, II and III. (Late summer): The transitions are similar to that in summer.
(Early autumn): The IV, V, VI, II and III patterns occur commonly. The continuity of same pressure patterns are dominant. Two groups of higher diversity (II, III patterns) and lower one (IV, V and VI patterns) are distinguishable.
(Aki-same): The occurrences of III and II patterns increase. The cyclic change between each patterns is indicated by entropy values.
(Autumn): The various patterns occur with high multiplicity. The cyclic change in Akisame is disturbed and the continuity of II pattern and the decrease of VI pattern are peculiar patterns.
(Late autumn): This season is characterised by the III, II and I patterns. The patterns transfer randomly.
(Early winter): The change of I→III→II→I pattern is dominant.
The entropy values show the random change. The I pattern has higher transition probabilities from other patterns than that from the same pattern.
(Winter): The I pattern is abundant, and has high continuity. The transition I→III→II→I pattern is common.
(Late winter): Transition patterns are similar to that of winter, however the high entropy values in this season show higher diversity than that in winter.
