GENERAL REPORT OF METEOROLOGICAL SECTION IN J.A.R.E. V, 1960-1962

Abstract

Meteorological observations at Syowa Base in 5th expedition were maintained in the year 1960-1962. Among scientific disciplines importance was attached to the meteorological section consisting of 4 members, to take various types of observation. General and characteristic features in meteorological observations are summarized in the following. A. Surface observation: 3-hourly observations were made throughout the wintering period, 4 observations were transmitted to Mother Station (Mawson), twice daily. In addition to the specified observations, radiation, sunshine and ground temperature were also observed by continuous selfrecording instrument respectively. The special features of this year is that, compared with the appearance of the annual minimum temperature normally in September in the Antarctic, the minimum occurred in July and it is shown that the average temperature in September was 5.5℃ higher than the normal value. B. Upper air observation: One time (12Z) daily rawinsonde observations were made throughout the year except a few cases of only radiosonde observation. Twice daily (00 and 12Z) rawinsonde observations were made during World Meteorological Interval of Post-IGY (July 16-July 25). All observations were transmitted to Mother Station every day. Equipments used : D-55A type Automatic Direction Finder (Similar type with GMD-1A) JMA-RSII Rawinsonde, 1680 Mc JMA-SIII Radiosonde, 27 Mc 800g Balloon (Latex) CaH_2 Cans for Hydrogen gas to fill balloons. Monthly average temperatures and heights were shown in respective figures. In September, combined with the surface temperature, the strong warm-air inflow throughout the troposphere below 300mb could be seen. A rapid warming in the stratosphere in spring was also clearly observed. Wind rose at some selected pressure levels were shown in Figs. 7-10. In general, the wind is strong in winter, especially in the stratosphere and NE-ly and SW-ly winds are predominant in the troposphere, SW-ly or W-ly in the stratosphere. The E-ly winds were also observed above 30 mb in summer. C. Ozone observation: i) Total ozone observation Dobson ozone spectrophotometer was used for this observation. Table 3 shows the results of only direct sunlight observation with reliable AD wave length setting. Comparison is made in Figs. 11 and 12 between Syowa Base, Little America and Halley Bay. Total ozone amount can be said to increase in spring from November to December over the Antarctic and the maximum seems to appear in summer. The 10-days average values of Syowa Base and Halley Bay show to be in good similarity in spite of different year. It may also be noted that a good correlation exists between rapid increase of ozone amount and temperature of 50mb in late November. ii) Surface ozone observation The density of surface ozone was measured on days without drifting snow from the end of February 1961. Based on Ehmert method, the equipment developed by Mr. KAWAMURA, Meteorological Research Institute, was used. It may be seen that the density increase in autumn and reaches its maximum value about 40 μg/m^3 in early June in polar night season, then decreases rapidly until the sun comes back and indicates minimum in early summer. It should be noted that there is 6 months' phase difference between the surface ozone amount and the total ozone amount. D. Special observation: Snow accumulation Toward ENE-ly direction from the base, 6 snow stakes were erected and snow accumulation was observed several times every month. The result is shown in Table 4 in which the annual accumulation was 121 cm. Average density of snow was 0.474 and the equivalent amount of water was 574 m/m.