Balloon‐Borne Observations of Short Vertical Wavelength Gravity Waves and Interaction With QBO Winds
Balloon‐Borne Observations of Short Vertical Wavelength Gravity Waves and Interaction With QBO Winds
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DOI：
10.1029/2020jd032779
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发表时间：
2020-08
期刊：
影响因子：
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通讯作者：
R. Vincent;M. Alexander
中科院分区：
文献类型：
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作者：
R. Vincent;M. Alexander
准两年期振荡（QBO）是赤道低平流层纬向平均纬向风的普遍特征，是由大气波的选择性消散造成的，周期从几天到几小时不等。然而，与观测相比，数值模型中的 QBO 环流往往较弱，这可能是因为垂直分辨率有限，无法充分解析重力波及其消散的高度范围。需要观察来帮助量化波浪效应。在QBO从东向西阶段20公里处过渡期间，超压气球（SPB）在赤道西太平洋无线电探空仪发射场附近通过，可以对周期分别接近1天和3天的两个惯性重力波包的固有频率和垂直结构进行协调研究。两种波的水平波长都很大，分别约为 970 公里和 5,500 公里。观测的互补性提供了有关动量通量和垂直波演化的信息。西行近1日波的临界高度在20公里附近，而东行3日波则能够传播到30公里附近的高度才消散。考虑到强迫的持续时间和规模，对动量通量收敛提供的强迫的估计表明，1 天波的纬向力约为 0.3–0.4 m s−1 day−1，3 天波的纬向力约为 0.4–0.6 m s−1 day−1，作用持续数天。
The quasi‐biennial oscillation (QBO), a ubiquitous feature of the zonal mean zonal winds in the equatorial lower stratosphere, is forced by selective dissipation of atmospheric waves that range in periods from days to hours. However, QBO circulations in numerical models tend to be weak compared with observations, probably because of limited vertical resolution that cannot adequately resolve gravity waves and the height range over which they dissipate. Observations are required to help quantify wave effects. The passage of a superpressure balloon (SPB) near a radiosonde launch site in the equatorial Western Pacific during the transition from the eastward to westward phase of the QBO at 20 km permits a coordinated study of the intrinsic frequencies and vertical structures of two inertia‐gravity wave packets with periods near 1 day and 3 days, respectively. Both waves have large horizontal wavelengths of about 970 and 5,500 km. The complementary nature of the observations provided information on their momentum fluxes and the evolution of the waves in the vertical. The near 1 day westward propagating wave has a critical level near 20 km, while the eastward propagating 3‐day wave is able to propagate through to heights near 30 km before dissipation. Estimates of the forcing provided by the momentum flux convergence, taking into account the duration and scale of the forcing, suggests zonal force of about 0.3–0.4 m s−1 day−1 for the 1‐day wave and about 0.4–0.6 m s−1 day−1 for the 3‐day wave, which acts for several days.