Desarrollo de la Antártica

Takesi Nagata I THE ADVANCEMENT OF SCIENTlFIC RESEARCH ••• an auroral flare, observed at Syowa station. In the figure, tille second line diagram represents a space·time diagram of green e1ectron auro– ra. The break-up of aurora corresponds to an onset of the expansion phase, whích is dharacterized by a sudden brightning oC electron au– roral internsity and the rapid poleward movement of tfue bright au– rora. Simultaneously with the auroral break-up, a sharp magnetic substorm of a negative bay type, the cosmic noise absorption (CNA) by tihe ionosphere, VLF hiss emissions, and ULF emissions (g,eomagne– tic pulsations) of PiE type take place. ¡n association with me later post break-up phase, which is characterized by the equatorward mo– vement of weaker e1ectro'll aurora, a broad negative bay type of mag– netic substorm, thehroad CNA-phenomena of a weaiker intensity, VLF chorus emissionsand ULF emissioris of P'iC type take place simulta– neously. 'J1he physical mechanism among these observable phenomena have been almost sufficientIy understood, though not completely yet. In Fig. 12, auroral break-ups at a higher latitude, w'hich are freo quentIy observable at the poleward horizon at a lower latitude, are associated with break-up type magnetic substorm at the higher la– titude, but only VLF hiss emissions are observable at the lower lado tude. This is because the VLF ¡hiss emissions are tlhe propagating elec– tromag,netic waves. 10. BIOLOGY ANn MEDICAL SCIENCES lÑ ANTARCTICA It could be said tllat fue 'Antarctic biology was practically started with the huntings of southem tur seals in the 1'8th Century and those oí southern elep,hant seals in the 19th Century. Because no control measure was taken for the conservation of these seals, they almost disappeared in the Antarctic Ocean (the Southern Ocean) area in the beginning of the 12(hh Century. The information of marine animals in the Antarctic Ocean given by the seal hunters and the Antarctic expedition team5 gave rise to the pelagic whalingactivities hom about 1925 to 11960.. IUnfortunately, the control measure for the preservation of whales also was not successful in the Antarctic Ocean, and consequently we are now facing an extreme shortness of Antarctic Ocean whale resources. In connection with the whaling businesses, however, the 'biological researches of wihales themselves and the general studies on marine biological systems such as the structure of ecosystem and the food chains have been markedly developed. Forexample, the extensive results of marine biological researches carried out by Discovery lIare the classic standard of marine