We have observed wind motions from 60 to 90 km altitudes with the middle and upper atmosphere (MU) radar during daylight hours (0800-1600 LT) from October 13 to 31, 1986. Gravity waves with fairly sinusoidal vertical structure were evident on 16 days of the 19 days of observations. They were characterized by a typical vertical wavelength of 5-15 km and intrinsic periods centered at about 8.6 hours. The propagation velocity of these waves was determined using the linear gravity wave theory. All of the waves propagated downward and had an equatorward component of the meridional propagation. The median direction of horizontal propagation was slightly east of south, and the mean horizontal phase speed was 35.3 m/s. The vertical wave number spectra of horizontal components of mesoscale wind fluctuations agree well with the theoretical spectrum of saturated gravity waves. At frequencies from 1 x 10 -5 to about 4 x 10 -5 c/s frequency spectra of vertical and radial wind components had logarithmic slopes of 1/3 and -5/3, respectively, which agree fairly well with a model gravity wave spectrum. The effects of Doppler shifting on frequency spectra are most obviously recognized at large frequencies near the Brunt Vfiisfilfi frequency. We have also determined the upward flux of horizontal momentum induced by waves with periods from 10 min to 8 hours and further esffmated the westward and northward body force of 5.1 and 4.0 m/s/d, respectively. ity waves have been determined by using a crosscorrelation analysis of wind fields measured by radars in regions horizontally separated by several tens to a few hundred kilometers [Vincent and Reid, 1983; Meek et al., 1985a; Yarnarnoto et al., 1986; Manson and Meek, 1988]. For gravity waves with periods less than 1 hour, Vincent and Reid determined typical values of about 70 km and 70 m/s for the zonal horizontal wavelength and zonal phase velocity at 80-94 km. Meek et al. determined horizontal scales ranging from 68 km to 119 km and phase velocity from 20 to 93 m/s for waves with intrinsic periods of 10-100 min. From meteor radar observations at 90-100 km Yamamoto et al. have determined ---25 m/s and ---360 km for mean values of zonal phase velocity and wavelength for waves with periods from 2 to 8 hours, and they also found that the westward propagating waves are dominant in winter. By using a linear dispersion relation Hirota and Niki [1985] studied characteristics of gravity waves from rocketsonde observations collected at 30-60 km altitudes.

SummaryThe light transmittance was empirically examined by using the beam of helium-neon gas laser ()t = 0.6328 #) propagated above the sea surface (1.6 m height). Simultaneous measurements were made on the relative humidity and the air temperature together with samplings of all the aerosols. Main findings from our experiments are as follows: Under the assumptions that the aerosols consist of particles of only sea-salt and sand, and the size distribution of sea-salt particles is expressible by Junge's form, the equilibrium relative humidity on the surface of droplet is estimable from the observed light attenuation and the sampling data of aerosols. The equilibrium relative humidity thus estimated, however, is found to be unreasonably high compared with the observed relative humidity' in the ambient air. To clarify this question, a high volume sampler is used in addition. And it is found that the concentration in the submicron range is remarkably underestimated. The size distribution is corrected, assuming that the particles of sea-salt and those of sulfuric and/or nitric acid are distributed according to Junge's form. And the observed light attenuation is satisfactorily explained by the use of the corrected size-distribution of these particles, combined with the observed size-distribution of sand particles. Zusammenfassung Laserlichtdurchl~issigkeit und die Aerosole fiber der Meeresoberfl~icheDie Lichtdurchl~ssigkeit wurde unter Verwendung des Lichtstrahls eines Helium-NeonLasers (X = 0,6328/l) fiber der Meeresoberfl~che (1,6 m H6he) empirisch untersucht.

Lateral fluctuation of the laser spot formed after passing through a distance of 2.26 km above the sea surface was observed together with the air, the surface water temperatures, and the relative humidity. Our main phenomenalistic findings were as follows: (1) a maximum value of the vertical displacement of the beam spot and that of its time rate were 2.1 m and 0.5 m/min, respectively; (2) the ‘large fluctuation,’ the displacement larger than 10 cm, was likely to occur just before the sunrise and, more remarkably, just after the sunset; (3) in each run of observation the frequency of such a large fluctuation seemed to be correlated with the changes in the air temperature and the relative humidity, and (4) an increment of the temperature gradient corresponding to the maximum displacement of 2.1 m was estimated to be 0.77 deg/m.

No abstract

A new method of sensible heat flux estimation by a hybrid use of temperature profile and light-beam deflection is proposed and tested over an asphalt pavement on fine days.A helium-neon gas laser with wavelength 0.6328 pm was used as a light-beam source. Temperature gradient near the surface was measured by the deflection of a light-beam propagated nearly horizontally at a distance of 25 m. Measurement of the air temperature profile in the upper part of the surface layer was made by means of a copper-constantan thermocouple thermometer. The sensible heat flux was estimated from the temperature profile using profile-flux relationships.The surface temperature of the asphalt pavement rose to as high as 63 "C in the daytime and never decreased below the air temperature even in the morning in summer. The maximum value of heat flux obtained from this observation attained 365 W m-z, which was about 48% of incoming solar radiation.