Diurnal fluctuation of meteorological variables above sloping terrain

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