Some features of the outer rain bands of typhoons are studied. A schematical illustration of surface pressure pattern in a typhoon is presented through the analysis of weather elements. It is shown from the radar echo analysis that the velocity of precipitation cells in rain bands is approximately equal to the resultant velocity of typhoon system and gradient wind, and that this fact may be used for the prognosis of movement of typhoons.
In section 3, we compute divergence and relative vorticity for each level at about 100-mb intervals from 950 to 300-mb by use of the observed winds. The results show that the patterns of divergence and relative vorticity are fairly smooth beyond our expectation. In the lower atmosphere, the maximum divergence is found slightly ahead of the cyclone in the contour field. In a broad sense, the magnitude of divergence is largest near the ground surface and weakest near 600-mb level. In section 4, we tried to perform the numerical forecasting at the minimum divergent level, namely 600-mb level. The non-barotropic forecasting, in which all terms in the vorticity equation are taken into consideration, is concluded to be fairly superior to the barotropic one, in which the stream function is used. This is accepted by the fact that, even in the minimum divergent level, the divergence term in the vorticity equation is of the same order of magnitude as the horizontal advection term.
The synoptic structure of Hurricane Hazel, 1954, over the eastern United States, is examined from the view point of Namekawa-Aoki's theory and of Namekawa-Sekioka's hypothesis. The result shows that Hazel has the same structure as that of typhoon hitting the Japanese Islands, i.e., Hazel is also composed of main and secondary typhoons, and she makes later herself a complex system with an extratropical cyclone formed on the preexisting front.
The forces which cause ice to move are provided by wind stress and water currents. In the present study the relationships between the movement of the surfaces occupied by comparatively thin ice-floes mostly in contact (so-called close ice-area) and the surface layer current and surface wind velocity are discussed at first and then a simple and easy method for forecasting the ice-area movement are presented using these relationships. Finally, the utility of this forecasting method is tested by applying it to actual examples on the coast of East-Hokkaido on February 1955.