Abnormal temperature rises were found in the lower stratosphere over the north subtropical Pacific after the 1982 eruptions of El Chichon. The significant temperature anomalies at 30 mb level moved westward with the El Chichon volcanic clouds.
   The positive temperature anomalies from the normal were simultaneously observed with the large backscattering ratios from the lidar measurements in the southern parts of Japan.
   The height-time cross section for the standardized temperature (T'=(T-T)/σ_T) showed warming in the lower stratosphere over the eastern and central parts of the north subtropical Pacific. In the above formula T is a monthly mean temperature, T is the normal and σ_T is a standard deviation. The magnitudes of the anomalies were in the range between σ_T and 2σ_T at most in this area. On the other hand, in the western part of the north subtropical Pacific, a stratospheric warming was spectacular.
   In particular, over Chichijima (about 27°N, 140°E) the air layer between 30 mb and 20 mb levels was abnormally warmed, with a peak anomaly of more than 5σ_T at 50 mb level in July and over 8σ_T at 20 mb level in September.
   In order to investigate northward diffusion of the volcanic clouds, the height-latitude cross sections of temperature anomalies along the 140°E Meridian were made every month from May to December 1982.
   Until June a positive temperature anomaly was limited to the south area of 40°N lat. over Japan. But in July it diffused north of the 40°N circle and the time variations of the monthly maxima of the direct solar radiation in USSR showed that the volcanic clouds passed through 50°N latitude in October and 60°N in November.
   Lastly it was found that the lower stratospheric temperature anomalies in the past three El Niño events did not show such remarkable warming as in 1982-83. They were all rather negative. Therefore it is not likely that the temperature rises in the lower stratosphere after the 1982 eruption of El Chichon was caused by the 1982-83 El Niño event.

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   The formation of typhoons in the western North Pacific and typhoon visits to Japan are investigated from a climatological standpoint. The relationship between the frequency of typhoon formation or typhoon visits and the sea surface temperature in the North Pacific is also studied.
   First, the formation of typhoons for the 30-year period from 1953 to 1982 is examined. The average number of typhoons formed is 27 a year. For the annual variation of monthly frequency of typhoon formation, the maximum frequency occurs in August and the minimum in February. Typhoons are formed most frequently in the ocean east of the Philippine Islands. The latitude of typhoon formation moves northward in summer and then retreats equatorward.
   Secular variation in the frequency of typhoon formation is studied by trend analysis and power spectrum analysis. The frequency showed a peak in the middle of the 1960's. The frequency of typhoon formation increased until the middle of the 1960's and then decreased. There exist two periodicities of 3 to 4 years and 6 to 7 years in the secular variation of typhoon formation.
   In the frequent/infrequent months of typhoon formation the following characteristics are found. The frequency shows a marked increase north of 15°N in the case of frequent typhoon formation. The polar vortex is weak/strong. The zonal index is high/low, because the Aleutian low is active/inactive and the subtropical anticyclone and the intertropical convergence zone exist north/south of their normal positions. The negative/positive anomalies of sea surface temperature are extensive in the subtropical ocean south of Japan.
   Next, typhoon visit to Japan is investigated for the period of 70 years from 1913 to 1982. When a typhoon approaches Japan and comes within a distance of approximately 300 km from the coast, it is designated as a typhoon that visits Japan. The average annual number of typhoon visits is 9. The maximum monthly frequency occurs in August and there are no typhoons from January to March in Japan.
   The area of the most frequent visits is the sea south of the Okinawa Islands. Typhoon visits are the least frequent in the sea northeast of the Hokkaido District. The frequency of typhoon visits is high in the open sea and straits and is relatively low near the islands and mountains. The typhoon season opens first near the Nansei Islands, and then the frequency increases also in northern areas. In the later typhoon season, typhoon visits occur frequently in the sea southeast of the Pacific coast.
   Secular variation of typhoon visit is examined by trend analysis and power spectrum analysis. The frequency is lower from the latter half of the 1920's to the 1930's. There exist high frequencies of visit from the latter half of the 1940's to the early 1950's and around 1960. The results also show the existence of variations of approximately 2 to 2.5 years and 5 to 6 years periodicities, in addition to a periodicity of 40 years.
   In years of frequent/infrequent typhoon formation, typhoons frequently/infrequently visit the coast from the Tokai District to the Kanto District.
   The annual variations of regional typhoon visit to Japan are studied by principal component analysis. The first four eigenvectors account for 97.5% of the total variance and the profile of the annual variation in frequency of regional typhoon visits is adequately described by the four eigenvectors.
   A regional division of Japan is proposed by using the amplitude coefficients corresponding to these four eigenvectors. Ten regions are obtained. Broadly speaking, these regions can be divided into four groups.
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   A system of equations suitable to follow meso-scale meteorological phenomena is presented. The system describes the non-rotating, non-hydrostatic, compressible and adiabatic, inviscid fluid motions and strictly preserves both the total mass and the total energy when it is applied to a closed domain.
   The finite-difference analogues to the original system are employed in the numerical simulation of the evolution of the mountain waves under a typical winter condition. The consequences show fairly good agreement with those of the linear, steady, non-hydrostatic Boussinesque solution, because of the gently sloping mountain profile adopted in the numerical simulation.
   The possible future development and merit of the present system are mentioned briefly.

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   In signal processings of weather radar, the input-to-output characteristics of precipitation echoes due to a linear receiver were investigated by taking into consideration the quantization effect and the deviation of the DC level in the A-D conversion.
   Though the bit-number of the A-D converter of the receiver gives essentially the quantization error for the signal processor, it is more suitable to configurate the system by adding the bit-number, which corresponds to the number of times integrating the fluctuating amplitudes of precipitation echo signal in a radar signal integrator, because the quantization resolution can be further improved.
   The condition for setting the DC level of the A-D converter is decided by the conventional radar signal processing rather than the MTI signal processing. And it is necessary to pay attention to the drift of the voltage from the point of view of the radar instabilities.
   The maximum-to-mean ratios of the amplitudes of the echo signals were investigated. It was found that the value, obtained by simulation in which the Rayleigh amplitude distribution was used for precipitation echo signal, was 2.4 and the measured values range from 2.7 to 4. However, no differences were recognized between the two cases as to the circuit responses in the upper region of the receiver's dynamic range.

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   In Japan now, spans between electrodes for geoelectric field observations are usually shorter than a few kilometers on land. Electric field observation with a long span of a few tens of kilometers was conducted by making use of the equipment of the Nippon Telegraph and Telephone Public Corporation (NTT). The cables connecting between the repeater stations and the grounded earths at each station were used for the electric field observation.
   The observation was conducted over the distance of 26.8 km from Shimodate to Kasama and the distance of 15.7 km from Shimodate to Oyama in northern Kanto. The variations were recorded with a two-penrecorder through low-pass filter with cut-off frequency 0.003Hz (about 1/6 cycle/minutes).
   Electric field variations associated with magnetic field variations were recorded in good condition between Kasama and Shimodate, and are very similar to those of the east-west component of the electric field at the Kakioka Magnetic Observatory. On the other hand, the electric field between Oyama and Shimodate was disturbed by large currents leaked from trains driven by direct electric power. In addition to this noisy environment, the amplitudes of electric field variations induced by magnetic ones seem to be much smaller between Oyama and Shimodate than between Kasama and Shimodate. The small amplitudes of the geoelectric variations at Oyama are considered to be closely related to the fact that the high conductive sediment is thick near Oyama.
   This test observation shows that the equipment of NTT is available to detect the geoelectric field variations induced by the geomagnetic ones. It was found that these observations are useful in detecting changes of subterranean electric conductivity structure, such as those prior to earthquakes.

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