背景风场维持的中尺度受导重力波

MEDIUM-SCALE GUIDED GRAVITY WAVESSUPPORTED BY THE BACKGROUND WINDS

提出了由上层大气背景风场所维持形成的中尺度重力波受导传播机制，通过一种新的全波解数值方法计算了这种受导波的色散关系和衰减距离与ＭｉｌｌｓｔｏｎｅＨｉｌｌ地区扰动的观测结果进行了比较。

A new propagation mechanism of guided gravity waves supported by the upper atmospheric wind is suggested in this paper. The numerical results show that,the existence of strong upper atmospheric winds make possible the long-distancemedium-scale guided gravity waves. The observed superior distributions of horizontal phase velocity at Millstone Hill are just correspond to those modes with longerattenuation distances. When the period of wave is smaller, the attenuation distanceof the guided wave strongly depends on the magnitude of wind speed along the antipropagation direction. The stronger the wind on the anti--propagation direction,the longer the attenuation distance, hence the more easily to be observed. Whenthe period becomes larger or the wind speed along the anti--propagation direction issmall, the ducting mechanism vanishes indeed. The above studies are in good accordance with the observation result at Millstone Hill, and give another interpretablepropagation mechanism of observed medium-scale gravity waves at mid--latitude.