Extensive observational programs on land and sea breezes were carried out by use of pibal method in the summer of 1971 and 1972 in the Tokai Village area facing the Pacific. Two pibal stations were set up at about one and six kilometers inland.Significant results obtained are as follows : (1) Vertical profiles of wind speed and direction in the lowest few hundred meters layer of the atmosphere in the sea breeze are significantly different between the coastal and the inland station, suggesting the effectiveness of the difference in surface friction over the land and the sea.(2) Low level jet in the evening is observed in this area and its development is deeply connected with the existence of a surface inversion layer. (3) The sea breeze observed is clearly of frontal type, which is about 400 meters thick in the vicinity of the front. The land breeze observed develops gradually from the ground surface upwards, under an opposing overriding flow.Observations of wind and temperature over the sea with a research vessel and those of air trajectories by use of tetroons were carried out as a part of observational programs. 418

The general aspects of land and sea breezes in the Osaka Bay area and its environment are revealed from an analysis of the wind data obtained by the AMeDAS. The study area consists of a complex land-sea configuration and a complex topography which includes plains, hilly terrain, and mountainous regions. The land and sea breezes are classified into five types according to the behavior of the sea breeze at several locations in the study area.The most frequently occurring type is characterized in the following. Along the southern coast of Osaka Bay, the sea breeze from Osaka Bay changes with time into that from the Kui Channel. At the same time, along the coast of the Seto Inland Sea the sea breeze contains a predominant easterly component. For this type, several interesting features are further elucidated: (1) the simultaneous onset of the coastal sea breeze and the valley or upslope wind in the mountainous region is clearly seen, especially in the eastern Chugoku area, (2) the meeting of the southerly sea breeze from the Seto Inland Sea and the northerly breeze from the Sea of Japan occurs around the region of the mountain ridges in eastern Chugoku, (3) the alternation of converging sea breezes from surrounding seas forms a uniform southerly sea breeze from the Kui Channel at Awaji Island, (4) the southerly sea breeze continues until the late afternoon in the coastal area of the Kui Channel and Osaka Bay.Other types are discussed and compared with the above type for the mature stage of the sea breeze. The relationships between the occurrence of the land and sea breeze and general meteorological conditions are also analyzed.

The general aspects of land and sea breezes in western Seto Inland Sea and the surrounding areas are revealed from an analysis of the wind data obtained from the AMeDAS. The study area consists of Kyushu, the western part of Chugoku, and the western end of Shikoku surrounded by the Pacific Ocean, the East China Sea and the Sea of Japan, and the study area contains inland seas both wide and narrow.The day of the land and sea breeze in the study area is specified from the day when the land and sea breeze appears on a coastal area in the middle of the study area. The appearance of unexpected wind directions in the sea breeze situation in that area and the presence or not of the sea breeze in a nearby coastal area of smaller water body are taken into account in the classification of types of the land and sea breeze; this classification results in eight types.The type of sea breeze in both coastal areas is characterized by the developed sea breezes all over the area, except for the northeastern half of the coast facing the Sea of Japan in Chugoku and the eastern end of the Seto Inland Sea. Meeting of the sea breezes in the central region from either side of Chugoku and Kyushu is clearly seen in the afternoon.The other types are discussed and characteristics are compared with this fundamental type. The location of a significant land breeze in northwestern Shikoku is noted in relation to the well-known local gale "Hijikawa-arashi."The results from the previous study of the relationship between the occurrence of the land and sea breezes and the general meteorological conditions in Osaka Bay and the surrounding areas are shown to hold also for the present area. By coupling the features of the sea breeze in the present study area and those in Osaka Bay and the surrounding areas, the typical features of the sea breeze for a wider area of western Japan are revealed. The interrelation of the behavior of the land and sea breezes in these two areas is also discussed.

A numerical model of the land and sea breeze which is based on the spectral method is proposed. This spectral model provides the diurnally cyclic solution without daily trends corresponding to the diurnally cyclic thermal boundary condition. The model takes the dependence of the eddy exchange coefficient on the atmospheric stability into account. In order to obtain the convergent solution properly by an iterative process, some elaboration is devised in the numerical aspects. Although the present model assumes a flat terrain and uniform field in the direction parallel to the coastline, the model simulates well the observed features of the land and sea breeze if observational sites satisfy the topographic conditions assumed in the model. It is evident from numerical experiments with the present model that the strength of land and sea breezes increases linearly with the temperature contrast between land and sea. Experiments with larger temperature contrast do not always provide the convergent solution for narrower land and/or sea configurations. Inclusion of the stationary components for the spectral model generates the feature of the land and sea breeze superposed on the stationary horizontal convection. However, the experiment with the present spectral model, when including the stationary components, results in divergence of the iterative process for a much smaller amplitude of temporal variation of the prescribed ground surface temperature than does the experiment excluding the stationary components.

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