Search

Suppression of climate change due to the emission of carbon dioxide is an important target of SDGs. To realize net-zero emission of CO2, the power industry has been tackling the issue with the use of sustainable energies and gas-fired generation based on chemicals that emit no carbon dioxide. The typical sustainable energies are solar cell, wind generation, geothermal generation, and biomass generation. Hydrogen and ammonia are thought to be promising gas without the production of CO2. The current situation of these energies is reviewed here.

This paper utilizes computer simulations to physical science and applications. High-temperature plasmas and macromolecules are reviewed first including magnetic reconnection in space and DNA translocation of the human body. The second topic is that water and salt-added saline solution are heated in elevated temperatures by microwaves, while the ice is frozen in complete ice structures and cannot be heated. The third topic is that a carbon-gold compound is driven by relativistic electromagnetic radiations and is accelerated as a nanotube accelerator.

This study investigates the dynamical variability of the double-jet structure in the Northern Hemisphere summer months of June and July. The summer northern annular mode (NAM), which is the leading mode of the empirical orthogonal function analysis in the extratropical troposphere for each month, is used for this analysis. The strong positive NAM is characterized as the double jets with the subtropical jet located at around 40°N and the polar front jet (the eddy drive jet) at 60°–70°N; the strong negative NAM is characterized as the single jet with the dominant subtropical jet at around 40°N. The vertical profile of momentum budget at 60°–85°N in the strong NAM months has peaks of the EP flux convergence and the poleward absolute vorticity advection at 300 hPa. The difference of zonal wind between the strong positive and negative NAM is estimated at around 5 m s⁻¹.

In this research, potential temperature gradient based vorticity which is the expression of baroclinic is obtained to analyze the energy structure of the vorticity field in developing clouds. First, applying the variational method enables us to obtain a diagnostic equation in which the equation of motion, conservation law of mass, and entropy are considered as constraints. Second, Fourier analysis was performed on the vorticity field in the cross-section of the convective core in the isolated cumulonimbus simulation. The temporal change of the spectrum of vorticity field indicates that the rotational intensity of potential temperature gradient based vorticity increases as the degree of baroclinicity increases. Third, we conducted the data assimilation experiment assuming the use of vertical vorticity estimated by doppler radar observation. The change in the potential temperature and vertical wind through the error covariance matrix generates coherent convection in the computations.

Field observation of wind fields has been carried out by using a doppler lidar and meteorological radars. Characteristics of fluctuational wind under cumulus convection and the growth of boundary layer including not only the effect of ground friction caused by surface roughness but also the effect of gust caused by up/down draft was examined and clarified. Some observed cases with the down flow under cumulus during passages of cold front were examined. The wind fields were simulated by large eddy simulation with canopy model, cloud physics model and boundary condition from simulated wind field by meteorological model WRF. The simulated wind fields consist with the observation. The wind speed near the ground increases with the down flow under the cumulus convection.

Wind variations in the atmospheric boundary layer (ABL) over a large plane were investigated. The data observed by a wind profiler and a windmill anemometer at Nagoya Local Meteorological Observatory of the Japan Meteorological Agency were used for the study of diurnal wind variations in the season of autumn. In the daytime, the decrease of wind speed in the morning and the subsequent increase of it in the afternoon were observed in the ABL. At the surface, wind speed gradually increases and attains a maximum in the afternoon. We infer that downward transfer of momentum by the convection and turbulent mixing cause the wind variations in the ABL and at the surface.

Localized heavy rainfall which resulting from isolated cumulonimbus often brings severe human and economic damages. Nakakita et al. developed a prediction system for torrential rainfall using vertical vorticity in a first echo using X-band Polarimetric Doppler radar (X-band MP radar) and Katayama et al. implemented this system. Besides, research on vertical vortex tube structure has been conducted. Nakakita et al. showed that with the development of the cumulonimbus cloud, a vertical vorticity structure with positive and negative pairs is generated. In this study, we analyzed the cumulous cloud with updraft, vertical vorticity, and hydrometeor. As a result, we succeeded in observing the behavior of the vertical vortex tubes, updraft, and hydrometeor.

We give a new derivation of higher order difference equations for interpolation Jack polynomials originally found by Knop and Sahi (1996). Our derivation is based on the Sekiguchi operators and twisted Pieri formulas for ordinary Jack polynomials., Mathematical structures of integrable systems, its deepening and expansion. September 9-11, 2019. edited by Takao Suzuki. The papers presented in this volume of RIMS Kôkyûroku Bessatsu are in final form and refereed.

論文(Article), The Peltier element has a structure in which metal electrodes, p-type and n-type semiconductors are alternately connected between two plates. When a temperature difference is applied between the two plates, a voltage is generated by the Seebeck effect. Then, we measured the output voltage generated by the temperature change in the flooded water due to convection using a Peltier element. The following results were obtained. (1) The Peltier element can detect temperature changes in the water due to convection. (2) The average and fluctuation of the output voltage of the Peltier element increased as the intensity of convection increased. (3) High positive correlations were confirmed between the averages of the output voltage of the Peltier element and the intensity of convection, and between the fluctuation ranges of the output voltage and the intensity of convection.

Intensive observations of wind and turbulence in the atmospheric boundary layer (ABL) were conducted in the suburbs of Kyoto City during the autumn season of 2019. During the daytime in the afternoon, strong winds in the lower ABL were observed by a Doppler lidar and a sonic anemometer. Intermittent occurrence of the further intensification of wind speed was also observed. During the period of strong winds, large-scale areas of upward velocity or high speed with temporal scales of approximately 80 s or more were detected by the Doppler lidar and sonic anemometer observation. The wind pattern of a high-speed area and a low-speed area resembles that of the coherent structure, which consists of a weak ejection (region of upward motion) and a strong sweep (region of downward motion).

Aim of using an electrostatic precipitator, there is reducing the generation emission under emission standard for industrial using. On the other hand, an air cleaner in home use, it is required to lower the concentration in the closed space with low power. Corona discharge is used in the pre-charger of the electrostatic precipitator, and the ozone is emitted. The increase in ozone concentration must also be required in the enclosed space. In this study, the reduction of the particle concentration when the electric precipitator was applied to the open and the closed spaces with calculated using MATLAB/Simulink. The differential equations were modeled and calculated. It is considered that this model can be developed to a model-based control of the electrostatic precipitator in the future.

It is aimed to analyze under what conditions thermals generated by the heat and shape effect of the city break through the atmospheric boundary layer. I used the urban meteorological Large Eddy Simulation model and the thermals over Kobe City are our targets. As a result, three factors were confirmed on the thermals which break through the atmosphere boundary layer. One factor is strong thermal buoyancy, and second factor is elimination of the stabilizing layer by another thermal and last factor is vapor amount. In addition, we could confirm the assembly of vortex. The assembly occur by vertical shear of horizontal wind. It is possible that the assembly strengthen each vortex. At last, I analyzed which factor is important for generating cumulus cloud.

Weathering of glass is a problem because it degrades the optical performance of the glass. The weathering occurs when the glass has been contacted with water in the long-term. In this work, a water/glass interface model was prepared and molecular dynamics simulation was performed to investigate the structure and properties near the water/glass interface. The broken surface of the glass network at near the interface was confirmed by the distribution change of the Qnspecies, and it suggests that the sodium ions are trapped by the destabilized glass surface structure.

In the design of a high-rise building, Wind load is calculated by wind tunnel test. Many previous studies conducted the accuracy verification of wind tunnel tests. However, there is no studies comparing the wind force coefficient observed at the building directly with the wind tunnel test. Because, it is difficult to observe wind force at the building. We observe the displacement of the seismic isolation layer, the wind direction and wind speed at the "J2" of the high-rise seismic isolated building. The wind force is calculated by the product of displacement and stiffness at the seismic isolation layer. Then we can calculate mean wind force coefficient and mean torsional moment coefficient by using observation record of wind direction and wind speed. In the wind tunnel test, we reproduced the topography and the surrounding buildings in detail, and conducted an experiment to confirm the effect of the topography and surrounding buildings. We compare observed data with wind tunnel test.

Accurate knowledge of air‐sea fluxes of momentum, heat, and carbon are central to fully understanding the evolution of the climate system. The role of ocean surface waves has been largely overlooked in global climate models despite the growing body of work elucidating the influence of ocean wave state on air‐sea fluxes. Here we account for the impact of ocean surface waves on global ocean climate using a global ocean model through implementation of wave‐dependent momentum fluxes. Wave‐dependent momentum fluxes improve the simulation of observed ocean heat content (OHC) through increasing the trend in OHC over the last three decades. Specifically, the larger increase in OHC is attributable to increased net heat flux in the Southern Hemisphere (SH). These results highlight the important role of accounting for wave‐dependent momentum transfer in terms of both simulating future climate and understanding changes over the recent historical period.

The radar volume reflectivity and turbulent kinetic energy dissipation rate in the Antarctic mesosphere were estimated from the polar mesosphere winter echoes (PMWE) recorded using a vertical beam of the PANSY radar, a Mesosphere‐Stratosphere‐Troposphere radar at Syowa Station (69°S, 40°E), over a period of 4 years. The observed radar volume reflectivity exhibits a lognormal distribution in the range of 2 × 10−18 to 5 × 10−15 m−1 for a height region of 55–82 km. The turbulent energy dissipation rate estimated from the spectral widths of the PMWE ranges from 10−4 to 100 m2 s−3. From monthly histograms of the turbulent energy dissipation rate for a fixed solar zenith angle (SZA) and height, it was found that the summer‐to‐winter transition of the turbulent energy dissipation rate occurs in March, while the winter‐to‐summer transition occurs in September. This seasonal variation agrees well with that of gravity wave activity, suggesting that the turbulence in the mesosphere is likely caused by gravity wave breaking.

Wind variation in the near-neutral atmospheric boundary layer (ABL) observed by the wind profiler of the Japan Meteorological Agency were investigated. The measured data at Nagoya Local Meteorological Observatory were used for the study of ABL wind in the large plane. In the daytime, the decrease of wind speed in the morning and the subsequent increase of them in the afternoon were observed in the ABL. From the diurnal change of the wind profile, we infer that turbulent mixing and the resultant downward transfer of momentum in the daytime can reduce the vertical wind shear. Wind variation in the time scale of 30 to 60 min is also found in the period of wind intensification.

It is aimed to analyze under what conditions the thermals generated by the heat and shape effect of the city breaks through the atmospheric boundary layer to generate cumulus clouds. Using the urban meteorological Large Eddy Simulation model, the thermals over Kobe City were targeted. As a result, the validity of the model was also assessed using the boundary layer radar. Two factors were confirmed on the thermals which break through the atmosphere boundary layer. One is strong thermal buoyancy, and the other is elimination of the stabilizing layer by another thermal. In addition, the relationship between the thermal and the vortex tube is also suggested, and further analysis will be carried out in the future.

The effect of the water level on free surface vortices in intake sump was investigated by numerical approach. A finite volume method with a RANS turbulence model and a VOF multiphase model was applied to solve the sump flow with a single intake channel. Multi-blocked structured grids and the open channel model were used to capture the flow behavior and their mutual interactions between air and water phases with higher accuracy. Air-water interface level, air-entrained vortex length, and air volume fraction contours and iso-surfaces were used to visually identify the location and shape of the free surface as well as surface vortices. By monitoring the vortex length with varying water level, it was found that that lower water levels induced stronger free surface vortices. The behavior of surface vortices and air bubbles caused by breaking off air-entrained vortices was explained well by using the volume rendering method and air volume fraction contours. The predicted velocity distributions at the entrance of bell mouth were in a good agreement with those of experiments.

Although the slope current under the Earth rotation effect has been well known at the steady state, the transient developing process of the slope current has not yet reported fully, and thus even the geostrophic current or wind is usually applied at the steady state only. This study has solved the time- dependent slope currents analytically and clarified the developing process from the initial stage. As shown in the previous paper in which the wind driven current has been reported changeable with the inertia period, it is revealed that the slope current is also grown with the inertia-periodical variation and that such variation is kept for a long duration. It might be a warning to the idea of the usual geostrophic current and wind with no consideration of the transient process.

When the water flowing from the nozzle collides on the fixed disc, the water spread horizontally on the disc. As a result, the hemispherical water film is formed. Because of the water film to be shaped like a bell, this flow phenomenon is called the water bell. For the beauty of the flow shape, it is mainly used for the fountain devices such as the park and the landscaping. However, the basic experimental reports on the characteristics for the flow shape of the water bell are not much seen. Therefore, it was classified into two types of the flow shape as basic data for controlling the flow shape of the water bell. In addition, it was investigated experimentally the characteristics of the diameter, the outflow angle and the film thickness of the water bell for the impact velocity, the flow rate and the collision disc diameter.

In this study, the simplified centrifugal pump used in the proof model was installed in a pond and the change in dissolved oxygen amount was investigated. The simplified centrifugal pump is driven by a motor and its rotational speed is controlled to be equivalent to the wind speed obtained from the relationship between the wind speed and the rotational speed in the proof model confirmed by the wind tunnel experiment. At the rotational speed equivalent to the wind speed of 14 m/s, effects up to about 10m in radius were observed.

Ice crystal growth by diffusion of water vapor from supercooled liquid water is simulated with equations written in a surface-following coordinate system. This two-dimensional system, similar to “terrain-following coordinate system” used in meteorology and oceanography, consists of the one axis pointing vertical and the other following the crystal geometry. It facilitates the introduction of the boundary condition on the surface of ice crystal so that simplifies the algorithm for computer programming. By introducing the system, the growth of one branch of snow crystal is simulated smoothly in contrast to the previous simulations adopting the ordinary rectangular coordinate system where it becomes bumpy. Also, while the rectangular coordinate system shows different growth rate and shape of ice crystal with grid resolution, those obtained from the surface-following coordinate system depend little on grid resolution.

This paper shows some results of intensive field observation carried out in the summer of 2016. The vertical profiles of currents and water temperature measured as well as wave and wind conditions, and salinity observations carried out at the observation tower of Shirahama Oceanographic Observatory. In the summer in 2016, one typhoon (TC16, MALAKAS) approached close to the observation site, and the high wave and strong wind conditions more than 40m/s captured during the observation. Under the high wave and strong wind condition, ADCP (Acoustic Doppler Current Profiler) measured high echo intensities for several hours, and this result indicates that strong mixing occurs. Water temperature variation at 30m deep has opposite phase to the fluctuation of salinity. This result means that low temperature and high salinity water approaches to the observation site. It is also found in water temperature distributions in November that some influences of the warm and cool water mass exist.

In Japan, the frequency of Guerrilla-heavy rainfall is increasing, so it is quite important to predict heavy rainfall even within a few minutes. Nakakita et al. (2016) discovered the large vertical vorticity inside the baby cell aloft is useful to predict the Guerrilla-heavy rainfall, and also discovered the baby cells have vertical vortex tubes. By these results, we considered that the horizontal vortex tubes were caused by vertical shear of horizontal wind and these were tilted into vertical by an updraft. This hypothesis is popular in large scaled clouds, but it is not unclear in small scaled clouds. This paper shows two findings. One is that the strongest updraft exists between positive and negative vorticity using high ZDR column and multi Doppler technique. The other is that Guerrilla-heavy rainfall is caused by not so strong vertical shear as liner convective system. These unlock the developing process of small scaled cumulonimbus cloud.

Convective genesis is subject of our research. The aim is understanding which factor is the most strong on the generating process and how strong urban areas have influence on convective genesis. Cumulus clouds above urban areas on summer were simulated by our model. The pair of vortex tubes that produce cloud droplet were analyzed. As a result, backward facing step flow and vertical wind shear came up behind buildings. They made horizontal vortex tubes. In addition, anthropogenic heat and sensible heat from surface and forced ascent by convergence of horizontal wind made upward flow and then vertical vortex tubes rises up with moisture.

We are studying on the development of teaching/learning materials in Science. This article focuses on a contextual science learning of the Earth’s origin and the hydrological circulation from the perspective of “water”. Some storylines about the origin of water, the gravity of planet, formation of the atmosphere and seas, and the creation of life are proposed in connection with the knowledge and concepts of physics, chemistry, and biology as well as earth science. And an example of lesson practice for state transition of “water” including the interdisciplinary aspects such as thermodynamics in physics and meteorology in earth science is also presented., 本研究はJSPS科研費（課題番号：JP25242015）の助成を受けたものである。

Solar wind speeds estimated by interplanetary scintillation on the source surface surrounding the sun are expanded into a spherical harmonic series. Wind speeds can be calculated on the Earth's orbit projected on the source surface, resulting in high reliable estimation of time variation of the solar wind speed in the vicinity of the earth.

We propose a neutron detector onboard a lunar rover for the survey of water in the lunar polar region. Neutrons leaking from the lunar surface are indicative of the location and amount of subsurface water (ice). Therefore, a neutron detector is expected to greatly contribute to the selection of locations for drilling in search of water (ice). This paper reports the status of the study on methods of water survey by a neutron detector on the lunar rover and the development of the detector., 第63回宇宙科学技術連合講演会

Offshore wind energy development promises to be a significant domestic renewable energy source. There are two approaches to estimating the increase in wind speed with height: the power law method and the logarithmic method. Logarithmic extrapolation is derived mathematically from a theoretical understanding of how the wind moves across the surface of the earth. In contrast, the power law equation is derived empirically from actual measurements. For an assessment of offshore wind energy resources by using the weather GPV (MSM-S and LFM-S) wind speed data at 10m above the sea surface, a new wind speed vertical extrapolation method based on a power law was proposed in the present study. In addition, the numerical investigation of the offshore wind energy in the Hibikinada region was performed.

Offshore wind energy development promises to be a significant domestic renewable energy source. There are two approaches to estimating the increase in wind speed with height: the power law method and the logarithmic method. Logarithmic extrapolation is derived mathematically from a theoretical understanding of how the wind moves across the surface of the earth. In contrast, the power law equation is derived empirically from actual measurements. For an assessment of offshore wind energy resources by using the weather GPV (MSM-S and LFM-S) wind speed data at 10m above the sea surface, a new wind speed vertical extrapolation method based on a power law was proposed in the present study.

In order to reveal the prediction skill as well as the key condition of the downward propagation of stratospheric planetary wave packets observed in early March of 2007, we conduct a series of ensemble reforecast experiments using the Ensemble Prediction System of the Meteorological Research Institute (MRI-EPS). It is found that the downward propagation in high latitudes of the lower stratosphere is predictable from about 8 days in advance. A regression analysis using all ensemble members indicates that the related circulation anomaly before the downward propagation resides within the stratosphere, but not in the troposphere. It is also suggested that the downward propagation is associated with barotropic instability of zonally asymmetric basic flow of the stratosphere.

The short lead time rainfall prediction by Numerical Weather Prediction model has some difficulties in the spin-up problem. Therefore, data assimilation (DA) is expected to improve the initial condition in the model. In this study, our developed ensemble DA system, CReSS-LETKF, and the method of estimation of ice-water mixing ratios are employed. DA of rain, graupel, ice crystal, snowflake and Doppler velocity estimated by polarimetric Doppler radar are carried out after the first convective cloud in mesoscale convective systems is generated. As a result, the first convective clouds formed in initial condition have effective influence on the short lead time rainfall prediction. As the next challenging step, DA is carried out before the first convective cloud. As a result, convective clouds are not generated although the atmosphere conditions, such as potential temperature change

In Japan, the frequency of Guerrilla-heavy rainfall is increasing, so it is quite important to predict the risk of heavy rainfall even within a few minutes. Nakakita et al. discovered the large vertical vorticity inside the baby cell aloft is useful to predict the Guerrilla-heavy rainfall, and also discovered the baby cells have vortex tubes which are similar to ones inside the initial cumulonimbus clouds of supercells. From this results, we considered that the vortex tubes inside the baby cells support fluid dynamics. This paper shows that the strongest updraft exists between positive vorticity and negative vorticity inside one sample cell using high ZDR column.

Previous models concerning diesel spray are impossible to calculate micro-explosion process and combustion process of water emulsified fuel. My study constructed mesoscale discrete particle models to simulate complex motion of emulsified fuel particles. Two models were constructed； micro-explosion process model and combustion process model of fuel droplet. These models based on cellular automata model which has a feature of both time and space discretization. Micro-explosion model simulates the microparticulated motion of vapor explosion. Furthermore combustion model can trace the combustion process of each microparticulated fuel droplet. My results show that emulsified fuel droplets burned rapidly rather than normal fuel droplets. Although these are simple models, it is thought that my models will be the base model to consider water emulsified fuel combustion theoretically.

The prediction of the aerodynamic noise generated from a small wind turbine is achieved based on the blade element method. The aerodynamic noise which is generated due to the wake vortex is recognized as a dominant factor of the noise. First of all, the accuracy of the prediction equation of the analytical model is validated in the wind tunnel experiment using the NACA00 series blades. The aerodynamic performance and noise of an actual wind turbine are measured in another suction type wind tunnel. Finally, the narrowband noise generated from the wind turbine was predicted by the wake characteristics deduced from the blade element method.

The prediction of the aerodynamic noise generated from a small wind turbine is achieved based on the blade element method. The aerodynamic noise which is generated due to the wake vortex is recognized as a dominant factor of the noise. First of all, the accuracy of the prediction equation of the analytical model is validated in the wind tunnel experiment using the NACA00 series blades. The aerodynamic performance and noise of an actual wind turbine are measured in another suction type wind tunnel. Finally, the narrowband noise generated from the wind turbine was predicted by the wake characteristics deduced from the blade element method., 長崎大学大学院工学研究科研究報告, 46(86), pp.1-6; 2016

We applied a wind acceleration device (wind-lens) to Vertical Axis Wind Turbines (VAWT), and examined power augmentation effects by wind tunnel experiments. We have investigated the optimum parameters of the wind-lens configuration. A wind-lens consists of a diffuser and brim. The increase in diffuser semi-open angle makes it possible to generate higher power output over a wide range of tip speed ratios. There is an optimum semi-open angle of diffuser. The inlet enhances power augmentation over a wide range of tip speed ratios. The best location of a wind-lens in the streamwise direction is in the center of VAWT. The curved surface type diffuser is more effective for power augmentation than flat panel type diffusers. The wind-lens demonstrates power augmentation with a curved surface diffuser by a factor of about 2.1 compared with a bare wind turbine.

It is well known that the problem of multipath propagation arises in the tracking low-altitude targets with a monopulse radar and causes large bias error in the estimated altitude of the target. Since the bias error caused by multipath propagation depends on a large number of parameters such as the frequency of the radar waveform, the actual target altitude, and range, it is difficult to estimate the bias errors. In this paper, we propose an altitude estimation method using particle filter and multipath propagation model. The performance of the proposed method is verified through computer simulations.

The diffusion phenomena of heat and pollutants caused by the heat convection or the turbulence flow in the non-isothermal field is one of the important phenomena concerned with the local heavy rain or air pollution. The large eddy simulation (LES) which can analyze the turbulence structures in the non-isothermal field is considered as one of the effective means for investigating those phenomena. The purpose of this study is to develop a computational method for the large eddy simulation of the turbulent transport of heat and vapor in the micrometeorological field. The equations for conservation of mass, momentum, heat and vapor are discretized by the finite volume method using a generalized curvilinear coordinate system, and the coherent-structure Smagorinsky model is applied to a subgrid-scale model. The large eddy simulations of the turbulent channel flow, the backward facing step flow, the Reyleigh-Bénard convection and the shallow cumulus convection are carried out to demonstrate the validity of this method.

The transition of tornado-like vortices is numerically investigated with the use of nonhydrostatic axisymmetric and three-dimensional models. Tornado-like vortices are generated by imposing a specified external force near the center axis of the computational domains that are rotating at a constant angular velocity. When the vortex transition from one to two-celled vortex occurs, there is an overshoot of the radial inflow near the surface. The overshoot flow turns upward, rebounding outward to a larger radius. At the same time, downdraft penetrates to the surface at the rotating axis. The overshoot is generated by coupled effects of inward advection and inward pressure gradient force. The downdraft is caused by downward pressure gradient. Thereafter, the two celled vortex transform to a multiple-vortex structure because the horizontal shear and Kelvin-Helmholtz instabilities occur in the non-axisymmetric flow.

A series of reforecast experiments using the ensemble prediction system of the Meteorological Research Institute is conducted to reveal the predictability and downward influence of a reflection event of stratospheric planetary waves in February 2014, which recorded the highest level of the downward propagation of the wave activity. The reflection is predictable from at least 7 days in advance. It is found that the skill of forecasts with a prediction period around the predictability limit crucially depends on whether planetary waves are reflected or absorbed in the stratosphere. Composite analyses also reveal that the persistence of the tropospheric wave source in the eastern hemisphere is a key in determining the propagating property of stratospheric planetary waves. When the reflection occurs in association with a weak persistence of the wave source, the subsequent downward propagating wave from the stratosphere enforces anomalous tropospheric circulation in the western hemisphere.

The influence of Madden-Julian Oscillation (MJO) on the extratropical circulation in the boreal winter (DJF) is statistically investigated using OLR data and JRA-55 reanalysis data during 35 years. We especially focus on response characteristics of atmospheric fields to the amplitude and polarity of MJO in each phase. It is found that the velocity potential field where its composited anomaly for the phase of MJO has statistical significance responds not only linearly to the amplitude but also symmetrically to the polarity. On the other hand, the stream function field has not such linear characteristics to the amplitude and polarity of MJO even though the composite anomaly has statistical significance. We also discuss relationship between the response characteristic of atmospheric anomaly fields to MJO and their formation mechanism based on the vorticity equation.

Geological feature, topography properties and climatic condition overlap variously, and the falling rock damage occurs. There are few studies on wind that is one of the inciting cause. Therefore we paid our attention to wind. It is a thought to be mechanism to cause ground vibration because wind goes through a tree. Focus on my attention to the wind and the relations of the tree by measuring the vibration that influence of the wind to shake a tree gave for ground vibration. The result clarified the distance from a tree and directional correlation with tree vibration caused by the wind giving vibration on the ground. In addition, I clarified it about the difference of the ground characteristic by the kind of the ground by measuring it on the ground where varied in the earth and sand ground and the bedrock ground.

A procedure for calculating trajectory of quasi-geostationary satellites is demonstrated. Satellite orbit is calculated based on the Kepler's law. A way of obtaining trajectory of the orbit in the sky observed from arbitrary point on the Earth is explained. Influence on the trajectory by orbit eccentricity and tilting angle to equatorial plane is under consideration.

Some devices which a gusty wind tunnel test requires to measurement of a lift force on a body were reported. The effect of an instantaneous drop in a reference pressure inside of the tunnel associated with a sudden change of wind speed was able to be avoided by putting a specimen between two aerodynamic balances. This measurement system is favorable to measure the wind forces of a body in three dimensional wind flows too. Using the system, it was found that gusty wind forces on a gable roof body under a two-dimensional flow and three-dimensional flow had some differences.

In this study, the relationship between the periodic noise and the aerodynamic noise source of a wind turbine is discussed. The aerodynamic characteristics and the noise of the actual wind turbine were measured by wind tunnel; the flow around the impeller immersed in the uniform flow was solved by numerical simulation. In the observed wind turbine, when the mainstream velocity was 7.4 m/s or more, the power coefficient became the maximum at the tip speed ratio 8. When the mainstream velocity became fast in the driving condition of the maximum power point, the aerodynamic noise became large due to the periodical noise in the vicinity of the 1000 Hz and the broadband noise in the high frequency domain. The noise sources were concentrated at the leading edge and the trailing edge on the suction surface side. We indicated that the pressure fluctuation of the leading edge was the noise source of the periodical noise.

In this study, the relationship between the periodic noise and the aerodynamic noise source of a wind turbine is discussed. The aerodynamic characteristics and the noise of the actual wind turbine were measured by wind tunnel; the flow around the impeller immersed in the uniform flow was solved by numerical simulation. In the observed wind turbine, when the mainstream velocity was 7.4 m/s or more, the power coefficient became the maximum at the tip speed ratio 8. When the mainstream velocity became fast in the driving condition of the maximum power point, the aerodynamic noise became large due to the periodical noise in the vicinity of the 1000 Hz and the broadband noise in the high frequency domain. The noise sources were concentrated at the leading edge and the trailing edge on the suction surface side. We indicated that the pressure fluctuation of the leading edge was the noise source of the periodical noise., 長崎大学大学院工学研究科研究報告, 44(83), pp.1-6; 2014

In order to evaluate the impact of missiles caused by tornado, a study on the velocity prediction of flying debris in a tornado-like vortex was carried out by numerical simulation. A series of unsteady flow fields of a tornado-like vortex was generated by Large Eddy Simulation. The aerodynamics of debris was examined and the range of aerodynamic parameters of debris resulting building damage was investigated. The trajectories of flying debris and the statistical distributions of the maximum speed of debris were obtained in various conditions i.e. the release height and the aerodynamic parameter of debris, the maximum tangential wind speed, the radius of maximum tangential wind speed and the traveling speed of tornado. Relation between the maximum ground speed of debris and the maximum wind and traveling speed of tornado was obtained as a function of aerodynamic parameter of debris.

A series of reforecast experiments by using the ensemble prediction system of the Meteorological Research Institute is conducted to investigate the predictability and occurrence mechanism of a stratospheric sudden warming event in January 2009, which is a typical polar vortex-splitting event. The polar vortex splitting is predicted for forecasts initialized after 8 days before the warming peak. It is found that in the failed forecast, the upward propagating planetary waves from the troposphere are reflected by the polar night jet and propagate downward into the troposphere. Thus, this study indicates that the propagating property of planetary waves in the stratosphere would be another important control factor for the occurrence of the polar vortex-splitting event.