第4次南極地域観測における輸送中の天気について

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1. Introduction The expedition ship "SOYA" was manned by three meterologists, who were in charge of weather forecasting for the operation as well as of regular ship surface observations and occasional radio-sonde observations. The weather analysis was made twice a day on the basis of the synoptic charts, 0600Z and 1800Z, which cover the whole southern hemisphere. This paper briefly reports the results of the analysis with respect to the area limitted between 40°W and 80°E. 2. Distinctive features of the synoptic pattern of this season a) A superior southward extension of subtropical anticylone was seen in January. b) The influence of the Antarctic continental anticyclone was predominant in middle December and in February. c) The change of weather phenomena in the vicinity of Lutzow-Holm Bay was considerably regular. d) There were two periods of conservative stable weather in the Antarctic coastal region, late December and early February. The former was caused by the southerly extension of subtropical anticyclone. 3. Cyclones The trajectories of major cyclones are shown in Figs. 1 and 2. Among these cyclones, two, which had developed in the area near Bouvet Island, approached Lutzow-Holm Bay, causing storms which attacked "SOYA" on Jan. 9 and 21. The relief operation was interrupted for a week or more before and after the storms. Another small depression, associated with the Antarctic front along the coast, hit Syowa Base on Jan. 31 giving minor effect on our operation. 4. Anticyclones a) Subtropical anticyclone. The quasistationary subtropical anticyclones, which are usually situated in the area between 20°S-45°S and 20°W-40°E, were developed so remarkably in middle January that their influence extended as far as to the Antarctic coast including Syowa Base, until the general pattern was changed by the approach of a deep trough at the end of middle January. b) Antarctic continental anticyclone. In middle December, Syowa Base and Lutzow-Holm Bay were under the control of the superior Antarctic continental anticyclone. But in middle January it rapidly retired to the south in early January, having been replaced by the high pressure ridge of the extended subtropical anticyclone. The continental anticyclone recovered its power again at the end of January. Then the Antarctic coastal region, from Queen Maud Land to Enderby Land, again went under the influence of the continental anticyclone, which reflected the movement of circum-polar cyclones to ENE, and Lutzow-Holm Bay remained out of the cyclone path. Thus, the stable weather lasted for about ten days in early February. 5. Antarctic front The so-called Antarctic front is a stationary one formed along the coast line of Antarctica. The physical aspect of the Antarctic front is quite complicated as has been revealed in our previous report. The remarkable Antarctic front, which was seen in middle January of this season, seemed to be of the occlude type. The daily position of the front for the period from Jan. 12 to 24 is shown in Fig. 3. An interesting relation was noticed between the movement of the cyclones along the front and the contact point of the front to the coast line, the details of which will be discussed in a latter paper. The sequence chart for Syowa Base was compared with that for Razarev Base, and a close similarity was found between them with respect to the weather change associated with the activity of the front.
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第4次南極地域観測における輸送中の天気について

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