Aerosol particles were collected with impaction technique at altitudes up to 3.0 km over three different locations in Japan: urban area (Nagoya), mountain (Mt. Norikura) and ocean (South Okinawa region). Individual aerosol particles larger than 0.5 μm in diameter (at 0 percent relative humidity) were analyzed with an electron microprobe. Elemental composition for silicon, sodium, and sulfur contained in collected particles were as follows: (1) Over Nagoya and its vicinity, the aerosol consisted often of particles rich in silicon and/or sulfur in and above mixing layer. (2) At the summit of Mt. Norikura, the aerosol consisted of particles rich in sulfur when convective activities were strong, whereas particles containing silicon and sulfur in large relative weight fractions and sodium in very small amount during nocturnal subsidence conditions. (3) Over the South Okinawa region, two regimes were clearly delineated: The aerosol consisted mainly of particles having the composition similar to the composition of sea water in marine layer, whereas particles having large relative weight fractions of silicon and/or sulfur as compared with the composition of sea water above the marine layer. The relative contribution of silicate, sea salt, and sulfate components in individual particles was estimated from the elemental composition for silicon, sodium, and sulfur contained in their particles. The result of these analysis suggests that mixed large particles (d≥0.5μm) containing silicate and sulfate in large relative weight fractions and sea salt in a minor constituent distribute widely in the free atmosphere over the Japanese Islands from Honshu to Okinawa.
Conventional PPI radar echoes which were associated with Typhoon 7617 in September 1976 are quantitized in the form of an echo coverage within a 10 km square grid over the area of 400×400km. A mean state of radar rainbands (MRB) which lies from sea to land and variability in the time series of echo coverage are discussed in connection with the rainfall amounts obtained by raingauges. The area of significant rainfall is in average concentrated into a few narrow bands which run almost parallel to the prevailing wind of the typhoon circulation. A main rainband runs perpendicularly to land, Shikoku with increasing its intensity and west-east width. A uniform magnitude of the variance with time and a predominant period with the order of one hour are obtained for the rain activity in the MRB. The two-dimensional (timespace) spectral analysis shows that the MRB consists of organized convective rain complexes with the predominant period of one hour. The complexes travel with the speed of about 20 m/sec and are separated longitudinally by about 50-100km in the MRB.
Life cycles of cumulus humilis clouds which have been observed by a stereophotogrammetric method are simulated by an axisymmetric numerical model with the observed atmospheric condition as the initial one. It is shown that when the ambient wind speed and shear is light, the simulated lifetime and the time variations of the cloud base height, cloud top height and cloud horizontal dimension agree well with the results of the observation. When the ambient wind speed and shear is strong, the simulated lifetime is more than twice of the observed result.
The present extended abstract outlines some important theoretical advances made in the last ten years in the field of atmospheric tides. On most topics included in the lecture, details and references can be found in Lindzen (1979). Only highlights will be sketched here.