An automatic aerosol counter is developed as a monitoring instrument for the atmospheric pollution level in an area. The counter is essentially similar to the 1957 Pollak counter with a slightly convergent light pencil and with under-pressure expansion. The present counter is characterized by its fog tube which consists of a single unit ceramic tube directly jacketed with water flowing at constant temperature so as to maintain the temperature and the humidity of the air sample just before expansion in the fog tube at the constant value irrespective of the ambient conditions throughout the period of long-term field operation. With the present counter, reliable aerosol concentration can be obtained every six minutes within ±10% of measured value, continually for a period of more than one year. In the present paper are described the details of improvements made on the Pollak type counter for long-term field observation and the performance of the improved instrument. An example is also shown of the results of field observation for one year with the present counter.
Behaviors of internal waves in a laterally bounded, uniformly or non-uniformly rotating fluids at Jones' critical level, where the Doppler-shifted wave frequency is equal to Coriolis frequency in magnitude are discussed. The solution is essentially singular at Jones' critical level, if the α-plane approximation is applied, denying the existence of such a non-zero regular solution at this level as suggested by Lindzen (1970). It is shown numerically that the wave is greatly attenuated and the zonal momentum flows into the mean zonal flow at this level. This opposes to a result by Lindzen (1970) that the attenuation of waves does not occur at this level for internal equatorial planetary-scale waves.
Multiple regression equation for typhoon track forecast was developed by means of screening procedure. Data selected as predictors were numerically predicted 500mb geopotential height and parameter showing state of typhoons in 194 cases of 48 typhoons which landed or approached Japan during 7 years from 1965 to 1972 except 1966. Verification using 1973 to 1974 independent data indicates considerably positive result in terms of forecast accuracy. As for the relationship between typhoon movement in 194 cases and 500mb geopotential height, it was revealed that negative correlation predominates between northward movement component and 500mb heights 1, 500 km north of typhoon center and between eastward movement component and heights 2, 500 to 3, 000km northwest of typhoon center.
Average vertical profiles of zonal and meridional components of winds, and of temperatures as obtained from M-100 meteorological rocket soundings conducted at Molodezhnaya, Antarctica in January-February 1972 (southern summer) are compared with those of the corresponding ascents from Thumba, South India. The actual results are also compared with the Groves atmospheric model and the corresponding departures of the actuals from the Model are worked out. It is found that in the southern summer the polar tropopause and stratopause were about 27°C and 13°C warmer than the corresponding equatorial tropopause and stratopause, while the mesopause was about 25°C colder. At both the stations the zonal winds in the stratosphere were predominantly easterly in January with speed less than 50ms-1, and westerly in February with speed less than 35ms-1, while the meridional winds were variable. Zonal wind departures of the actuals from the Groves model were found to be in a range of about ±35ms-1, while the temperature departures were mostly negative by about 25°C.