The equations of infrared radiation transfer are numerically solved for the Martian atmosphere, with consideration of the effect of dust, which absorbs, emits and scatters light. Primary mineral constituent of dust, we assumed, is quartz. Three cases on dust concentration are considered: the first corresponds to a heavy dust storm event, the second to a dusty case and the third to out-of-storm case. From the solutions obtained by the method of an iterative numerical integration, radiative heating or cooling rates in the atmosphere are calculated as a function of height. The computation results show that on Mars, the infrared radiative cooling rates due to dust cannot be overlooked in the lower levels within dusty atmosphere. Especially, at a dust storm event, cooling in the infrared regions would be a very important term as well as heating due to absorption of the incident solar radiation by dust, and the thermal structure of the Martian atmosphere seems to be determined by dust alone. Our result also indicates that even at out-ofstorm events, cooling rate due to dust seems to have the same order as the magnitude of infrared radiative cooling due to CO2.
A numerical study of three-dimensional Benard convection is carried out to determine the amplitude of convection as a function of Rayleigh number, Prandtl number and horizontal plan forms of convection cell. We treat three types of plan forms, namely, square, rectangle and roll, all of which have the same horizontal wavenumber. The calculations are carried out for air and water in the range of R≤8Rc, where R is prescribed Rayleigh number and Rc is the critical Rayleigh number. The upper and lower boundaries are assumed to be free-slip and conducting. The variables such as velocity, temperature and pressure, are expanded in a series consisting of the eigenfunctions of the linear stability problem and the system is truncated to take into account only a limited number of terms. The amplitudes of the eigen-functions are evaluated by numerical integration of resulting non-linear equations. The main results are summerized as follows. (1) In all cases considered, the system achievs a steady state, a single mode being dominant. (2) The non-dimensional amplitudes of convection increase except perturbation temperature as R increases. (3) The velocity pattern depends on Prandtl number more markedly than the temperature pattern does in the three-dimensional convection. On the other hand, in the two-dimensional convection, the dependences of velocity and temperature patterns on Prandtl number are very small. (4) The dependence of vertical heat flux on horizontal plan forms appears more markedly for air than for water. In the case of air Nusselt number for the two-dimensional convection is larger than that for three-dimensional convection. (5) The reversed gradient of horizontally averaged temperature is found in the middle layer at high Rayleigh number. The gradient is larger for the two-dimensional convection than for the three-dimensional convection. (6) The energy budget of convection indicates that the most characteristic difference between threedimensional and two-dimensional convections is found in the conversion rate of kinetic energy through inertial term, that is, the conversion rate for two-dimensional convection is much smaller than that for three-dimensional convection.
The second order mean motion induced around an internal Rossby wave packet, having an infinite zonal length and propagating vertically in an inviscid Boussinesq fluid at rest in a channel, is discussed, and the validity of photon analogy to such a wave packet is examined. It is shown that the second order mean zonal momentum averaged in the meridional direction is just equal to the wave momentum E/C (where E and C are the wave energy and the phase velocity in the zonal direction respectively). This guarantees the validity of photon analogy to the wave packet, and also implies that the treatment done rather intuitively in the previous paper by the author (Uryu, 1974) is essentially correct. It is shown that, to the first order in ∈ (where ∈ is a small parameter characterizing the slowness of variation of wave amplitude), the vertical component of Lagrangian mean velocity is zero, as a result of the cancellation between the Stokes drift and the Eulerian mean velocity. The case of propagation in a shear flow is also treated, and it is shown that the absorption of wave at the critical level occurs as a result that the wave momentum is stored up in the mean zonal flow there. It is also shown that the results obtained in case of Rossby wave packet can be obtained without any essential change also in case of internal gravity wave packet under the same situation.
As a preliminary observation of AMTEX, GARP, the modification of a mesoscale cold airmass over Ishikari Bay was measured in January 1972. A wide-spread steam fog was produced over the sea surface with a temperature of +2.5°C by the outflow of cold air with a temperature of -11.5°C and a humidity of 60 %. The thermal diffusion coefficient of the air was estimated as 0.7 m2•sec-1 in the range between the surface and the 9 m height above sea level near the seashore under the wind speed condition of 3 m•sec-1, by measuring the height of the fog top, besides the vertical structure of the outflowing cold air. Based on this value of diffusion coefficient, the heat flux was estimated as 1, 500 ly•day-1.
Measurements of the total aerosol concentration and the size distribution of large particles have been performed over the North and South Pacific ocean from November 18, 1971 to March 10, 1972. It was found that the concentration was about 300 cm-3 on an average over the South-Pacific and 450cm-3 over the North Pacific. Both the concentration and the size distribution of large particles depended on the wind force and showed a pronounced peak around 0.4×10-4cm in radius.