Tower Stations Research Articles

HEIFE領域における境界層の風速場

Simultaneous wind data collected from micrometeorological tower stations and automatic weather stations have been used to investigate the principal features and seasonal variations of the wind fields in the HEIFE experimental area. Besides wind statistics from a less modified data set, a MASCON wind model was adopted in an objective investigation of the three-dimensional atmospheric boundary layer flow during IOP-2 and IOP-3. The results have shown that synoptic scale, mesoscale and sub-mesoscale motions play different roles in different places. Under strong wind conditions, a northwesterly wind is predominant in the area with significant features of mechanical constraint by the mesoscale topography. On fair weather days, the flow patterns exhibit strong diurnal and spatial variations. In the sites adjacent to the north slope of Qilian Mountain and along the valley axis, flows featuring thermal forcing by mesoscale terrain are apparent, but daytime flows show significant seasonal shifts due to the link with the synoptic winds. Around the northern part of the experimental area, diurnal variations of the flows show a more complicated site-dependent behavior, which is caused by the simultaneous influences of synoptic-scale wind and the flows induced by small-scale topography.

Meteorology and cooling tower operation

Because of its wide experience in the use of natural draught cooling towers, the Central Electricity Generating Board occupies a unique position in a discussion of environmental effects. A number of papers have been produced in other countries on climatic effects, claiming for example that the incidence of ground-level fog would be increased, and that precipitation from the plume would become a hazard, particularly in freezing conditions. Where salt water was used, the countryside would, it is claimed, be seriously affected. The climatic aspects have been studied at several of the many cooling tower stations in the U.K. and provided natural draught towers are designed properly and well maintained, the impact of their operation has been found to have a negligible effect on the local climate. A salt water tower station has also operated for many years with negligible effects. A persistent elevated plume, which occurs under conditions of high ambient relative humidity and aggravates the adverse visual impact of the large bulk of the cooling towers themselves, appears to be the most objectionable atmospheric feature.

Systematic Errors in Tellurometer and Geodimeter Measurements

From an analysis of field measurements made by the Geodetic Survey of Canada in 1969-1970, on about 200 lines in different localities and generally between 7 and 27 km long, it is clear that 1) there is a systematic diurnal variation in geodimeter measurements between ground stations, with daytime measurements about 4 ppm longer than nighttime measurements; 2) systematic diurnal variations of a few ppm sometimes occur in a network of tellurometer measurements from either ground or tower stations, and 3) tellurometer measurements are generally 2-5 ppm shorter than geodimeter measurements. There is a general agreement between the observed discrepancies and those that can be predicted from Best’s model of temperature and vapor pressure variations in the lower 100 meters of the atmosphere. From this it can be concluded that 4) the mean of day and night geodimeter measurements between ground stations, or a measurement made near sunrise or sunset, is reliable; 5) systematic meteorological errors in geodimeter measurements between tower stations are generally less than one ppm, and 6) tellurometer measurements are generally a few ppm short.