No abstract

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.

No abstract

Block copolymer lithography is a promising method for fabricating periodical nanopatterns of less than 20 nm by self-assembly and can be applicable for fabricating patterned magnetic media with a recording density over 1 Tb/in.2. We found a simple technique to control the orientation of cylindrical microdomains in thin films. Simply by mixing polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) diblock copolymers with the homopolymer (PS or PMMA) of the major component, we could align the cylindrical microdomains perpendicular to the film surface. The added homopolymer induces conformational entropic relaxation of the block chains in microdomain space and stabilizes the perpendicular orientation of hexagonally packed cylindrical microdomains. Thus formed perpendicular cylinders can be readily aligned in a regular array with a grating substrate.