Structure and Evolution of Numerically Simulated Squall Lines

摘要: Abstract Using a three-dimensional numerical cloud model, we investigate the effects of vertical wind shear on squall-line structure and evolution over wide range magnitudes, depths, orientations relative to line. We find that simulated squall lines are most sensitive magnitude component perpendicular line, may reproduce much observed structures by varying this single parameter. For weak shear, line initially upright-to-downshear-tilted short-lived cells quickly tilts upshear, producing band weaker extending behind surface outflow boundary. moderate-to-strong circulation remains upright-to-downshear tilted for longer periods time, with vigorous, confined relatively narrow along system's leading edge. At later times, however, these systems also weaken as upshear. strong, deep shears oriented obliquely squal...