Seasonal transitions and Climatic variations from the viewpoint of the occurrence frequency of atmospheric pressure patterns over East Asia are discussed in the recent 45 years (1941-1985). The category of the pressure pattern types which was formed by Yoshino (1968) has been applied to many studies (ex.: Nomoto, 1975; Komabayashi and Nakamura, 1976; Hohgetsu, 1979; Hayashi, 1987). The pressure pattern calendar on the basis of this category was made by Yoshino and Fukuoka (1967), Yoshino and Kai (1974) and Yoshino and Yamakawa (1985).
The following is the classification of main pressure patterns over East Asia in this study.
I: West-high, east-low pattern or winter monsoon pattern.
II: Trough pattern.
II a: passing low over Hokkaido (the second biggest, northern island in Japan) or north of it.
II b: Passing low over the Sea of Japan.
lI c: Passing low along the Pacific coast.
lI d: Passing coupled lows across Japan.
III: Migratory anticyclone pattern.
IV: Stationary frontal pattern (The defined area of this category is shown in Fig. 11).
IVa: Stationary front over Honshu (the biggest, main island in Japan).
IVb: Stationary front along the Pacific coast of Japan.
V: South-high; north-low pattern or summer monsoon pattern.
VI: Typhoon pattern.
The main results in this study are as follows: 1) Six seasons and one specific period in Japan are recognized (Fig. 12) from the viewpoint of occurrence frequency over 30% during 1941-1985 of the main pressure pattern types: namely each index are Type I for the winter season, Type III for the spring and autumn seasons, Type V for the summer season, Type N for the Baiu season (early summer rainy season), Type (IV+II b, c, d+VI) for the Akisame season (early autumn rainy season) and. Type VI for the Typhoon period.
2) The pentad (Nov. 2-6) including November 3, which is called the specific fine weather day, occupies the pretty much high frequency (51%) of migratory anticyclones. While in the pentad of April 11-15, the equivalently and considerably high frequency (52%) of migratory anticyclones appeares. (Fig. 3, Fig. 12).
3) A singularity pentad of cyclonic or frontal pressure patterns accompanying the cloudy or rainy weather is June 25-29 (Fig. 7, Fig. 12), which was indicated by Maejima (1967, 1968).
4) Around 1980, the Baiu fronts were more active over the Japanese Islands and were apt to cause heavy rain, as same as in the 1960's (Fig. 5).
5) In the latest years (1971-1985), the autumn rainy season due to the fronts and cyclones became more active (Fig. 7, Fig. 12).
6) The frequency of typhoons approaching to the Japanese Islands decreased during about the latest years, especially in autumn (Fig. 10, Fig. 12).
7) In the latest years (1971-1985), comparing with the former years (1941-1970), the secular features of seasonal phenomena are noticed (Fig. 12); i, e, prevailing and longer winter, less frequent migratory anticyclones in the earlier spring, active Baiu fronts in the later period, less prevailing summer, more frequent autumnal fronts in the earlier and longer period, and less frequent migratory anticyclones in later autumn were often appeared. Probably, there is no causal relationship between these phenomena, but there are the correlations due to some causes of astronomy, upper air chemical content and circulation, sea or glacier.

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Certain correlation and chronology of marine terraces are very desirable to clarify the sea level records and vertical tectonic movements using former shoreline heights preserved on them. The terrace correlation study in each area has often led to greatly different interpretations among the workers, although late Pleistocene marine terraces are continuously distributed in the coastal areas of northern Northeast Japan (Fig. 1). This paper aims to reexamine the previous terrace correlation by tephrostratigraphic method using two widespread tephra layers, the Toya ash (Toya, ca. 90ka) and the Aso-4 ash (Aso-4, ca. 70ka), in addition to geomorphicc method using characteristics of terrace features and terrace deposits and to estimate the age of marine terraces on the basis of the age of the time-marker tephra layers.
In this paper, the Kamikita Coastal Plain was applied to the standard area for the correlation and chronology (Fig. 2). Among the terraces of this plain, the Takadate surface has the widest development, the thickest terrace deposits and the highest fossil sea cliff suggesting the relatively great transgression. These permit the interpretation that this surface was formed at the last interglacial culmination stage ca. 120-130 ka ago (Fig. 3). The Tagadai surface is the lowest terrace which is overlain by the airlaid Toya ash and the Nejo surface is the lowest which is overlain by the airlaid Aso-4 ash (Fig. 3). The Tagadai, Nejo and Shibayama surfaces are tephrochronologically estimated to have been formed at the interstades ca. 100, 80 and 60 ka ago, respectively.
Marine terraces correlated with Takadate and Tagadai surfaces were identified in many areas and a marine terrace correlated with the Nejo surface was identified in the western Shimokita Peninsula (Fig. 13), based on the correspondence of the stratigraphic tephra-terrace relation in the Kamikita Coastal Plain with that in other areas. In addition to such correlation criteria, the width of terrace surfaces, the thickness of terrace deposits and the relative height of fossil sea cliffs were mutually compared. Conclusively, the former shoreline height on the Takadate surface extensively became certain (Fig. 14).
While the age of two well-developed marine terraces younger than the Toya ash can not be tephrochronologically determined in most areas, except for the western Shimokita Peninsula. These are probably correlated with the Nejo surface ca. 80 ka ago and the Shibayama surface ca. 60 ka ago in descending order, judged by the comparison of the terrace sequence in the Kamikita Coastal Plain with that in other areas. This extensive correlation and chronology imply that at least four stages, correlated with the worldwide high sea level stages during late Pleistocene, occurred in the study region.

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The applicability of the models for isolated cities (e, g., the Clark model) has been identified in studies of urban population density. As for the application of the model for multi-centered cities presented by Griffith (1981), however, two problems exist. First, parameters of the model do not directly indicate the morphological features of population density distribution. Second, the model does not make a satisfactory prediction of population density, especially for regions where density profiles overlap. The purpose of this paper is to improve the Griffith model in the above aspects and to examine the population density distribution and its changes in multi-centered cities. This study limits the subject to twin cities as the simplest forms of multi-centered cities. If it is assumed that a density crater does not appear in the centers, the Griffith equation is written as
d (s, t)=d_Aexp (-as)+d_Bexp (-bt),
where d (s, t) is the population density at distance s from the center A and distance t from the center B; d_A, a, d_B, and b are parameters.
The following new indices of the morphological features of density profiles are defined by combining parameters which cannot stand alone: i, e., outside density gradient, inside density gradient, connectivity of population density, and equilibrium point of population density.
We developed a new model by adopting the concept ‘bias’ to show spatial distortion of population density. By substituting biased distance for physical distance in the Griffith equation, the new model's equation becomes
_??_
where s* and t* are biased distance written as
_??_
d (s*, t*) is the population density at the location P, namely at distance s from the center A and distance t from the center B; d_A, a, d_B, and b are parameters; λ is ∠PAB; μ is ∠PBA; β is the degree of bias, and the attributes of β are as follows: (1) The range of its value is between -1 and 1. (2) The absolute value shows the strength of bias. (3) The sign shows the direction of bias. (4) If β is zero, the new model is equivalent to the Griffith model.
In this study, the Clark, the Griffith, and the new model are applied to three districts : the Numazu-Mishima, Shizuoka-Shimizu, and Maebashi-Takasaki districts. The results of the applica-tions of the new model are summarized as follows: (1) The applicability of the new model is higher than that of the other two models. (2) In Numazu-Mishima and Shizuoka-Shimizu, the outside density gradient is more relaxed than the inside gradient. This indicates that in these districts the urbanized area has grown outward rather than inward (3) The connectivity of population density increases gradually in three districts. This indicates that each of the pairs of urbanized areas are becoming spatially connected. (4) The degree of bias is positive in Maebashi-Takasaki, where the connectivity is relatively low, while in the other two districts, the degree is negative. The degree of bias tends to decrease in all three districts. (5) A negative correlation between the connectivity and the degree of bias is identified from (3) and (4).

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