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Wind speed data were taken at a weather station on the coast and horizontal wind speed energy spectra were computed. The shape of an average spectrum obtained in marine environment is compared with an average land spectrum and the presence of a spectral gap is observed in the shoreline spectrum. Wave number domain spectra are compared with frequency domain spectra. Strong similarity between the spectra is found for short periods, but at longer periods the f-space spectrum localizes most of the energy at specific frequencies, while the k-space spectrum spreads the energy over many wave numbers. When the wind speed is fairly constant, Taylor's hypothesis is found to be a reasonable approximation up to periods of tens of minutes. A preliminary investigation of the dependence of the value of the drag coefficient on the period over which the average wind is measured was made. A line of the form C[subscript Dx]/C[subscript D₁₀]= .89 + .1 log X fits the graphed points quite well with a correlation of .98, where X is the averaging distance in miles. Differences of 20% in the value of the drag coefficient over averaging distances between 10 and 1600 miles are observed. From this preliminary study, it appears that a more detailed study of this effect would be worthwhile. / Graduation date: 1972

The wind field measured during Project JASIN 1972, a joint British-American venture during September 1972, was analyzed. These measurements were done, with equipment manufactured by Ivar Aanderaa of Bergen, Norway, on large, anchored toroid buoys. The results of the analysis of the wind field, which included divergence and vorticity estimates and spectral analysis, compared favorably with results from previous studies by other investigators. The spectral analysis of the wind field at different locations showed some differences indicating that ocean wind fields are less homogeneous than had been expected. Basic statistics of the wind speed and direction at the same locations also confirmed this conclusion. An apparent diurnal cycle in the u and v components of the wind was studied. It was shown that the total wind vector for the study period was quite different at different horizontal locations while hourly deviations around these means during a day showed remarkable similarities. A curious eight-hour period found in the divergence estimates on a 100 km grid is possibly related to an eight-hour air pressure wave studied many years ago by Von Hann (1918) and Bartels (1932). It was concluded that the wind field over the ocean is not entirely homogeneous and some rather large differences are found over a scale as small as 100 kilometers. / Graduation date: 1974

The data recorded between March 3, 1969, and October 31, 1969, by a wind gauge installed at the South Jetty, Newport, Oregon, were analyzed. The components of each observation were treated as if they were an independent, normal, bivariate distribution and standard statistical procedures were applied. It was found that the wind gauge is obscured by the land to the southeast and that the adjacent land has the effect of channeling the wind so that it comes from the north, the east, and the south. The seasonal and diurnal wind shifts were observed and described. It was noted that the orientation of the diurnal shift changed with time; it rotated clockwise from March to July and counterclockwise from July to October. / Graduation date: 1971

Two land breeze events occurred off the Oregon coast on the nights of April 19th and 20th, 1973. An array of four moored toroid buoys and one land station recorded the effect of the land breeze event on the surface mesoscale wind and temperature fields. The land breezes may have resulted from the premature summerly conditions of fair weather and southward coastal winds that were caused by an early northeastward extension of the North Pacific High. The main features of the events were as follows: 1) A cooling period of a few hours after sunset established an air temperature gradient of -0.1° C km⁻¹ in the nearshore 10 km region. 2) The advance of the land breeze-front produced a 5° C temperature drop at the land station and a 1° C temperature drop at the buoy stations. 3) Simultaneously, the front also caused a decrease in wind speed by about an order of magnitude at each of the stations. During the passage of the front the wind veered from southward at 10 m sec⁻¹ to westward at 2 to 3 m sec⁻¹. 4) At dawn the temperature gradient was rapidly reversed, but there was a 2 hour lag before the wind speed began to increase. No frontal return flow was observed, instead the wind backed to the south and increased gradually over the array. Horizontal divergence and vertical vorticity were calculated using a simplified program. The land breeze produced spans of positive vorticity (5 x 10⁻⁴ sec⁻¹) over the array, possibly due to the horizontal wind shear in the offshore direction. The land breeze also caused a zone of convergence over the nearshore 10 km. The convergence was preceeded by a brief period of intense divergence. There was no convergence zone beyond the nearshore region. Instead there appeared alternating bands of convergence and divergence with a period of around 37 minutes. The same periodicity was observed in the offshore wind velocity. These features can be explained by a model of horizontal roll vortices migrating seaward from the nearshore convergence zone. The roll wavelength is inferred to be 4.7 km, the westward migration speed is 2 m sec⁻¹, and the height of the PBL is estimated to be 1. 5 km. This leads to a PBL Reynolds number of 370 ± 80, which is lower than previous observations and suggests that the rolls are produced by buoyancy and parallel instability. A model which is compatible with all the above is presented. / Graduation date: 1975

The Risø data were analyzed for variations in the surface roughness lengths. The method of analysis was tested on the Wangara data and proved satisfactory at this homogeneous site. Annual mean surface roughness lengths were determined for three wind speed categories and three stability categories. The decrease in surface roughness length with increasing wind speed and decreasing stability was large but not generally statistically significant because of the large dispersion in the data. The annual mean roughness length varied over several orders of magnitude. These results and also the ten year mean profiles were compared with those of previous investigators. It was found that the standard deviation determined from mean annual profiles over a ten year period was greater than one order of magnitude. / Graduation date: 1975

Surface meteorological data collected at a mesonetwork in Colorado during the 1973 National Hail Research Experiment were analyzed to see if a diurnal oscillation of boundary layer wind exists and also to determine the mechanism that drives the wind system. The average temperature, pressure, and wind velocity for a month's time were computed in order to filter out synoptic disturbances. The analysis of averaged daily potential temperature distribution shows that, during the study period, air is always stable along the slope at night and is stable over 75% of the time during the daylight hours. This implies that nighttime downslope flow is driven by baroclinity and strongly influenced by frictional effects. This analysis also shows that differences in horizontal potential temperature are minimal at the time of day when hail activity is statistically a maximum. Hodographs obtained from averaging wind velocities show that the air flow is upslope during the afternoon and downslope at night. This type of air movement is attributed to baroclinicity caused by diurnal heating along a slope. Spectral analysis of wind speeds at two stations shows numerous peaks and valleys in various spectra. Several of these peaks are attributed to diurnal and inertial oscillations. / Graduation date: 1975

The wind and thermodynamic fields associated with eastern Atlantic cloud clusters are studied using radiosonde data from the Global Atmospheric Research Program Atlantic Tropical Experiment (GATE). These data are from the gridded set of winds prepared by Dr. Katsuyuki Ooyama (AOML-NOAA) and Dr. Jan-Hwa Chu (SSEC, University of Wisconsin, Madison) using an objective analysis scheme designed by Dr. Ooyama. Similarly-analysed thermodynamic data prepared by Dr. Steven Esbensen (Oregon State University) are also used. Case studies of the vorticity budget for the 4 September squall and the 5 September cluster show significant contributions by all budget terms including the residual, which is interpreted as the effects of cumulus convection, mesoscale cloud lines, or other small-scale circulations. The residual is particularly large in the boundary layer and upper troposphere. The fields of winds and vorticity budget terms in the upper troposphere of the two systems are similar. However, at the level of the mid-tropospheric jet, the small-scale production of vorticity is significantly different in the two systems. A technique for compositing clusters using satellite-derived cloud-top data is applied to GATE data from Phase 3. Vertical motions within and below the anvils are in accord with previous studies. Frictionally-induced inflow is found to be of secondary importance to the development and maintenance of cluster circulations. The composited vorticity budget residuals are again large in the boundary layer and upper troposphere. A large-magnitude asymmetric vorticity couplet observed in the upper troposphere of individual clusters and in composite results is examined. Cluster-scale twisting and motions at meso- or smaller scales are found to produce the couplet, while cluster-scale divergence is the primary destructive agent. A deceleration of the strong easterlies at this level produces these couplets. Possible mesoscale and cumulus sources of this deceleration are discussed. Present schemes that parameterize vorticity production by cumulus convection are found to be inconsistent with similar schemes that parameterize momentum production. Furthermore, these vorticity parameterizations cannot describe the production of the upper-tropospheric couplets discussed above. An alternate parameterization, formed by taking the curl of the parameterized momentum source, does qualitatively describe the couplets. / Graduation date: 1984

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 123-129).

Inaug.-diss.--Upsala. / "Reprinted from Bull. of the Geol. institut. of Upsala, v, xx." "Litteraturverseichnis": p. 224-230. Translated by O. Zdansky. of. Einleitung.