The mechanism of the ozone transport by planetary waves in the winter stratosphere is considered on the basis of a quasi-one-dimensional model, developed by Hartmann and Garcia (1979), where meridional distribution of physical quantities are expressed by two modes. In the present study we consider wave-mean flow interactions as well as dynamical and photochemical effects on the variation in ozone content. It is found that the meridional and vertical transports of ozone due to waves depend on the vertical structures in their orientation and magnitude. Our finding regarding the characteristics of ozone transport in wavenumber 1 is different from that reported by Hartmann and Garcia in the sense that southward transport dominates in the upper stratosphere above 30km height. This discrepancy is due to the difference in the vertical wave structures, because it is found that upward propagating waves bring about southward transport of ozone while internally trapped waves (nearly no phase change with height) bring about northward transport in the upper stratosphere. The results below 30km that northward and downward transports dominate are nearly in agreement with Hartman and Garcia. Similar characteristics are confirmed also in the results for wavenumber 2. Detailed discussions on the dependency of ozone transport on the vertical wave structure are made in terms of amplitudes and phases of wave. The transport characteristics in this paper are well consistent with the recent observational analysis of ozone transport due to large-scale eddies reported by Gille et al. (1980). Variations in the meridional distribution of mean ozone is studied. It is found that net poleward transport takes place more effectively by the waves with internally trapped structures than by those with propagating structures.
Due to the extremely low moisture content of the air and the underlying desert surface over North Africa during the summertime, solar radiation works effectively in heating the desert surface. Because the earth's surface receives more radiative energy from the sun than it loses in the form of infrared radiation during the day, a large amount of radiative energy is transferred from the ground to the atmosphere in the form of sensible heat flux. The horizontal differences in the upward flux of sensible heat between North Africa and equatorial Africa build strong surface baroclinic patterns. A real-data forecast using a multi-level primitive-equation model was designed to study the influences of solar radiation and the associated diurnal variations in surface temperatures on the dynamics and energetics of the African low-level circulations. A surface energy budget which included solar radiation, infrared radiation, sensible heat flux, and latent heat flux was employed in estimating surface temperatures. The effects of cloudiness on radiation processes were also considered, and heat and moisture exchanges due to turbulence inside the boundary layer were parameterized. The upward transfer of heat from the boundary layer to higher levels in the atmosphere was carried out by a dry convective adjustment. Two numerical experiments, one with solar radiation and another without, were performed and the energetics of each forecast were examined. Results clearly indicated the important role played by solar radiation in the maintenance of low-level motions. With solar heating, which preserved the rather unique thermal structure in North Africa, the model produced a very realistic forecast in the circulation patterns. Without solar heating the model substantially underpredicted the intensity of wind circulation over North Africa. Large diurnal variation in response to solar heating was noted in the dynamic fields and model energetics.
Synoptic analysis was conducted of interannual variations of the tropical summer monsoon circulation during the 17-year period from 1964 to 1980. The 150mb wind speed at 10°N (40°E-110°E) were read from the analyzed maps and used to represent the fluctuations of the tropical easterly jet stream (TEJ). The strength of the TEJ was used as an indicator of the strength of the tropical summer monsoon over Asia (10-30°N, 40-130°E). Evidence has been shown that the interannual fluctuations of the summer monsoon are under the strong influence of the middle latitude circulation of the northern hemisphere. When the monsoon is strong, the circulation near 50°N is zonal. On the other hand when the monsoon is weak, a blccking high develops to the north of the Caspian Sea and a trough develops near 50°N, 110-120°E. The Walker circulation plays a smaller role compared to the winter monsoon. However major El Nino years (1965, 1972, 1976) were found to be the years with weak monsoon. The 1979 MONEX summer was one with a weak monsoon. Only 3 of the past 17 summers (major El Nino years) had weaker monsoon compared to the MONEX summer.
Theoretical considerations on the Ekman pumping actions in the planetary boundary layer are made for small scale cyclonic vortex with the horizontal dimension of about 100km. These are applied to the nocturnal small-scale cyclonic vortex which is formed in the Ekman layer of the Kanto plains. It is analytically shown that a secondary circulation is superposed on a primary one. An upward and a radial motion maximum of the secondary circulation are estimated 2.5cm s-1 and 1.5m sec-1 respectively. Although surface friction will cause a decrease in angular momentum of the circulation in the friction layer, the relative distribution of angular momentum shows an increase in the lowest layer and a decrease above the Ekman layer. This will be a result of the work done by the cross-isobaric flows due to the secondary circulation, and will be an indication of the action of Ekman pumping.
The structure of thermal plumes in the atmospheric mixed layer was investigated using the data from airborne measurement. The scale of turbulence and number-density of a thermal plume were analyzed and a structure model for describing these parameters is proposed. Also, the ascent velocity of the thermal plume was estimated using this model.
The relationship between the height of the stable layer and the height of the aerosol layer nearest to the ground on sunny days was examined using radiosonde and laser radar observations. Aerosol layer heights were determined by the normalized (aerosol) concentration gradient. Good correlation was found between the lowest-level stable layer and the lowest aerosol layer top (correlation coefficient=0.87) and also between the stable layer stability and the vertical gradient of the aerosol concentration at the aerosol layer top (correlation coefficient=0.78).
This paper presents a study of infrasonic waves generated by the explosions of the volcano Sakura-jima, and detected by the microphone array in Kariya, at a distance of about 710km. The geometric ray analyses using the rawinsonde and rocketsonde data show that these infrasonic waves are channeled mainly in the tropospheric duct, formed by the strong westerly wind in the upper troposphere. The propagation in the stratospheric duct which is also significant in winter season, is less frequent owing to the occasional destruction of the winter westerlies by the stratospheric Aleutian anticyclone over Japan. The infrasonic signals may provide a tool to monitor the upper stratospheric flow, if combined with the temperature data from satellite observations.
It is well known that the second order differential mobility analyzer is an excellent apparatus. In this apparatus, we can expect to obtain mobility distributions with good resolusion and to reduce the errors involved in the data analysis process. For these reasons, we developed a new differential mobility analyzer of second order. This analyzer was constructed to scan the mobility range from 3×10-4 to 5×10-2cm2/v•sec, which corresponds to the size range of 4×10-7 to 4×10-6cm in radius. In this apparatus, the mobility resolution is determined by four factors; the flow rates of filtered clean air and aerosol sample air, and the lengths of the first and second inner electrode. The resolution of the present analyzer was about 0.4. In this paper, we present the principle of the measurement of mobility distribution and experimental set-up of the analyzer, together with some examples of the mobility distribution and aerosol size distribution.