In order to clarify the influence of orography and land-sea distribution on the large scale atmospheric circulation, numerical experiments are performed by using a two-level geostrophic spectral model under winter conditions. The numerical time integrations are made for the model with mountains and oceans, the model with mountains and no ocean, the model with oceans and no mountain and the model without mountains and oceans. The results of the numerical simulations of the atmospheric general circulation performed by these four models are analyzed and compared to reveal the relative im. portance of the dynamical effect of mountains and the thermal effect of land-sea distribution in determining the large scale features of the atmospheric circulation.
The results thus obtained are summarized as follows:
1) The atmospheric and surface temperatures are h igher by 10° to 15°C in all latitudes in models with the ocean than without, because of the heat release from the ocean to the atmosphere in the winter season.
2) The latitudinal gradients of t h e atmospheric and surface temperatures are smaller in models with the ocean than without the ocean. This is caused by the fact that the amount of heat released from the ocean to the atmosphere is relatively large in middle latitudes.
3) I n models with mountains, the mountain torque dissipates the angular momentum on the hemispheric average. This lack of angular momentum is compensated for by the generation of it due to the surface torque in order to maintain the angular momentum balance. In models without mountains, the generation of angular momentum due to the surface torque vanishes on the hemispheric average.
4) Standing eddies grow in models with mountains. On the other hand, in models with the ocean and no mountain, the standing eddies are very weak.
The computed spectral distribution of eddy kinetic energy i n dicates a maximum at the wave number 2 for standing eddies and at the wave number 5 to 6 for transient eddies. The spectrum of total eddy kinetic energy as seen in the actual atmosphere (existence of the maximum at the wave number 2) is reproduced qualitatively by models including mountains.
5) As for the computed eddy conversion of available potential energy to kinetic energy, the maximum conversion is found at the wave number 2 for standing eddies and at the wave number 5 to 6 for transient eddies. The spectrum for models with mountains is in qualitative agreement with the observed (the primary maximum being at the wave numbers 5 to 6 and the secondary maximum at the wave number 2).
6) Through non-linear interaction, kinetic energy is transferred from eddies to zonal currents in each model. The spectrum of this energy transfer is in qualitative agreement with the observed (the maximum being at the wave number 2) in models with mountains. In this case, standing eddies play an important role.
In models with mountains, the energy exchange between e ddies and zonal currents is performed through mountain effect as well as through non-linear interaction. The flow of energy is from zonal currents to eddies in the energy exchange through mountain effect.
7) In models with mountains, the available potential energy and kinetic energy of standing eddies are transferred to those of transient eddies, respectively, as seen in the actual atmosphere.
8) The large scale features of the atmospheric circulation in the winter are determined primarily by orographic effect. Especially, it should be noted that the Siberian high and the American continental high over the continents and the Aleutian low and the Icelandic low over the oceans are simulated in qualitative agreement with the observed by the model with mountains and no ocean.

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A method of determining friction velocity u* by measurement in a wind-wave tunnel is proposed, based on the similarity law of the turbulent boundary layer. The method is based essentially on the application of a two-layer model to the velocity defect profile a logarithmic velocity distribution is applied to the inner boundary layer and Hama's profile, F=9.6(1-η)², to the outer layer, where F is the non-dimensional velocity defect function,η the non-dimensional height.
This method can determine f r iction velocity u* within a few percent of uncertainty, and has higher accuracy than the logarithmic method generally used, in some case of wind-wave tunnel experiments. The method works with precision if used in the early stage of development of the turbulent boundary layer, but not if used in the later stage, when the turbulent boundary layer has fully developed and the whole air flow in the wind-wave tunnel becomes turbulent.

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In order to estimate the daily snowfall amount on the Japan Sea side of the Japanese islands in the winter season, statistical analysis and statistical method for estimation of the daily snowfall amount at each station in Niigata prefecture are discussed. The various distribution functions fitting to the observed frequency distribution at each station are discussed. They follow Poisson distribution function on the coast of the Japan Sea, polya-type distribution in the mountain districts and exponent-type distribution in the intermediate districts. As they are too far from the normal distribution function, it is suggested that some treatment, such as the discriminant analysis method, is desirable. The statistical relationships of the classified daily snowfall amount and various meteorological data at Wazima are discussed. The statistical study of severe snowfall indicates extremely low temperatures and instability from the ground surface to the middle layers of the troposphere and higher temperatures and stable layers in the upper levels. In the case of moderate snowfall the condition reverse. In the lower parts of the cold dome, the vertical transfer of sensible heat and water vapor from the sea surface is remarkable. It was also shown that such a situation exerts an influence on the Bulk-Richardson-Number in PBL. Discriminant functions for the classified daily snowfall amount at each station are contsructed from the above statistical analysis. Using independent data, verification of the acuracy of the discriminant functions is also made. This discriminant method is found to afford more information than the conventional climatological method.

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Four types of volcanic earthquakes and two types of volcanic tremors are observed at Asamayama volcano. They are named A-type earthquake, B-type earthquake, T-type earthquake, explosion earthquake, short period type volcanic tremor and long period type volcanic tremor, respectively.
Relations betw e en amplitudes (A) and durations (t) of the vibrations of each type of volcanic earthquake are expressed in the form of t=kA^α, but the two types of volcanic tremors are not explessed by this equation. In this equation, a is 0.4 for every type of volcanic earthquake, and the value of k is 104.7 for T-type,37.8 for A-type and 35.5 for B-type earthquakes.
The value of m in Ishimoto-Iida's relation is calculated to be 1.9 for A-type earthquakes,3.2 for B-type earthquakes and 1.0 or 3.2 for T-type earthquakes.
The spectra of seismic waves for each type of volcanic earthquake are compared, using the data of three component seismograms at three observation stations. The maximum value of the spectrum is detected at 4 Hz for A-type, at 2--3 Hz for B-type and at 1.5 Hz and 2-4 Hz for T-type earthquake. The prevailing periods of seismic waves of the explosion earthquakes are 1 sec., and those of the short period type volcanic tremors are 0.3-0.5 sec., and of the long period type volcanic tremors are 0.6-0.8 sec.
The above-mentiond different values for each type of volcanic earthquake and volcanic tremor clearly show the features of different types.
The frequency of occurrence in percentag e of each type of volcanic earthquake during the period from 1966 to 1977 was 99.60% for B-type,0.20% for A-type,0.13% for T-type and 0.06% for explosion earthquakes.
The relation between the vo l c anic eruption and the A-type earthquake is remote, and that between the B-type earthquake and the short period type volcanic tremor is close. But the T-type earthquake and long period type volcanic tremor are not so closely related to volcanic eruptions.

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