The stack velocity calculated on the floating datum depends on the velocity of medium underlying the low velocity layer and is independent of topography and low velocity layer.
在此浮动基准面上求取的叠加速度仅取决于低速带底板下伏介质的速度，而与地形、低速带无关。
2
The special topography, climate conditions and the underlying surface with the source of the abundant sand were the material base of forming sand and dust storm.