Premium
Measurement of the pressure field on a mountain
Author(s) -
Vosper S. B.,
Mobbs S. D.
Publication year - 1997
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49712353705
Subject(s) - anemometer , drag , wind speed , hydrostatic pressure , geology , drag coefficient , hydrostatic equilibrium , streamlines, streaklines, and pathlines , pressure gradient , surface pressure , density of air , meteorology , environmental science , atmosphere (unit) , wind direction , atmospheric sciences , mechanics , physics , quantum mechanics
Abstract Four microbarographs, accompanied by wind vanes and anemometers, were deployed on a mountain called Black Combe (height 600 m) in Cumbria during a field experiment that took place in Novemberer 1991. the aims of the experiment were to measure the small flow‐induced pressure differences across the mountain and relate these to the local wind. These pressure differences may be used to calculate directly the drag exerted by the atmosphere on Black Combe. The mean pressure difference between pairs of sites calculated over periods when the wind speed is small is due to the hydrostatic pressure difference caused by the height differences between the instruments. Removing this component reveals pressure differences across the mountain of up to 2 hPa. the main result of the experiment is the high correlation of the pressure differences with differences of the quantity pu 2 /2, where p is the air density and u is the wind speed. It is shown that this result holds for a stratified fluid when far upstream the streamlines originate from levels of similar wind speed. Although reliable data were only obtained at three of the four stations, making the assumption that the dynamic pressure varies linearly across the mountain surface enables an estimate of the drag to be made. the average drag exerted on Black Combe over the period of the experiment is estimated to be 3.6 Pa.