This study investigates the hydrodynamic variations in the coastal region of Nan-bin, Hualien influence by the topography and water stratification. The data used were collected from four cruises of field observations in 2008/4/29¡B2008/9/5~6¡B2009/3/17~18 and 2009/7/21. Instruments applied include sb-ADCP and CTD. Parameters recorded include flow velocities, water temperature and salinity and tidal elevations. The collected data are analyzed through a variety of time series analysis technique, including buoyancy frequency EOF analysis, potential vorticity and kinetic energy. The results show that (1) the flow field and vorticity in the south side of Hualien Harbor indicate there exist a counterclockwise eddy during flood. The flow pattern reverse to be a clockwise eddy during ebb. The current speed and vorticity is smaller in the surface layer, while the bottom current speed and vorticity is much larger. (2) Currents in transects of along slope, along canyon and along shore all reveal two layers flow separated around 25m, with upper layer flowing eastward and lower layer westward. The current velocity reaches to a maximum at 55m, and the current directions were dominated by the orientation of bottom topography. The baroclinic kinetic energy increase to 0.15m2/s2 along the down slope transect, while the up slope kinetic energy reduced to 0.05m2/s2. (3) The CTD data suggest that the upper layer is warm-fresh water due to river outputs, while the lower layer is dominated by cold-salty open ocean water. (4) The density interface at 25 m is confirmed by buoyance frequency analysis. The EOF analysis of density distribution shows eigenvalue of first mode has maximum at 53m, while the second mode has peaks at 25m and 65m, which match well with the vertical of distribution of flow structures.

Some passive houses are provided a warm supply flow inlet coming from a mechanical ventilation system, creating issues of shortcut ventilation as a result of an originated density layer stratification, since the supplied warm air is confined to the ceiling level. In this way, there exist several complaints of thermal discomfort and poor indoor environmental quality in passive houses. Thus, a method of periodic variation of the ventilation supply frequency is an option to increase mixing, aimed at de-stratifying the room conditions. A small-scale water model is employed in order to systematically explore the influence of the created standing waves from the supply input frequency and its interaction with stratification characteristics in the studied volume, hence operating with water as a working fluid and a paddle as an oscillating mechanical input. Measurements at three different input frequencies and at three input paddle locations have been performed, gathering vertical temperature gradients and visualization data from them. Thus, ventilation efficiency of passive houses is set to improve, consequently increasing their public acceptability, via reaching buoyancy resonance, i.e., matching the input frequency with the internal Brunt-Väisäla frequency of the fluid. Consequently, the shortcut ventilation issues may be mitigated and the public acceptability of passive houses increased, achieving a higher thermal comfort and economic and energy demand savings, while enhancing sustainable and renewable heating alternatives such as the heat recovery from the outgoing exhaust flow.

A Rayleigh-scatter lidar operated from Utah State University (41.7°N, 111.8°W) for a period spanning 11 years ― 1993 through 2004. Of the 900 nights observed, data on 150 extended to 90 km or above. They were the ones used in these studies related to atmospheric gravity waves (AGWs) between 45 and 90 km. This is the first study of AGWs with an extensive data set that spans the whole mesosphere. Using the temperature and temperature gradient profiles, we produced a climatology of the Brunt-Väisälä (buoyancy) angular frequency squared, N2 (rad/s)2. The minimum and maximum values of N2 vary between 2.2×10-4 (rad/s)2 and 9.0×10-4 (rad/s)2. The corresponding buoyancy periods vary between 7.0 and 3.5 minutes. While for long averages the atmosphere above Logan, Utah, is convectively stable, all-night and hourly profiles showed periods of convective instability (i.e., negative N2). The N2 values were often significantly different from values derived from the NRL-MSISe00 model atmosphere because of the effects of inversion layers and semiannual variability in the lidar data. Relative density fluctuation profiles with 3-km altitude resolution and 1-hour temporal resolution showed the presence of monochromatic gravity waves on almost every night throughout the mesosphere. The prevalent values of vertical wavelength and vertical phase velocity were 12-16 km and 0.5-0.6 m/s, respectively. However, the latter has the significant seasonal variation. Using these two observed parameters, buoyancy periods, and the AGW dispersion relation, we derived the ranges of horizontal wavelength, phase velocity, and source distance. The prevalent values were 550-950 km, 32-35 m/s, and 2500-3500 km, respectively. The potential energy per unit mass Ep showed great night-to-night variability, up to a factor of 20, at all heights. Ep grew at approximately the adiabatic rate below 55-65 km and above 75-80 km. Step function decreases in Ep imply that the AGWs in between gave up considerable energy to the background atmosphere. In addition, Ep varies seasonally. Below 70 km, it has a semiannual variation with a maximum in winter and minima in the equinoxes. At the highest altitudes it has an annual variation with a maximum in winter and a minimum in summer.