摘要：The quasi-biennial oscillation (QBO), a dominant mode of the equatorial stratospheric (~100–1 hPa) variability, is known to impact tropospheric circulation in the middle and high latitudes. Yet, its realistic simulation in general circulation models remains a challenge. The authors examine the simulated QBO in the 69-layer version of the Institute of Atmospheric Physics Atmospheric General Circulation Model (IAP-AGCML69) and analyze its momentum budget. The authors find that the QBO is primarily caused by parameterized gravity-wave forcing due to tropospheric convection, but the downward propagation of the momentum source is significantly offset by the upward advection of zonal wind by the equatorial upwelling in the stratosphere. Resolved-scale waves act as a positive contribution to the total zonal wind tendency of the QBO over the equator with comparable magnitude to the gravity-wave forcing in the upper stratosphere. Results provide insights into the mechanism of the QBO and possible causes of differences in models. 摘要 平流层准两年振荡 (QBO) 是赤道平流层 (~100–1 hPa) 变率的主要模态, 可对中高纬地区的环流产生重要影响, 但目前利用通用大气环流模式 (GCM) 对其进行准确模拟仍然是一个挑战.本文利用IAP大气环流模式 (IAP-AGCM) 的中高层大气模式版本 (IAP-AGCML69) 对QBO进行模拟, 并对其动量收支情况进行分析.研究发现, QBO主要是由对流活动引起的重力波强迫 (参数化) 引起的, 但该动量强迫被平流层赤道上升流所引起的平流过程显著削弱.模式可分辨尺度的波动强迫对赤道上空的QBO的总纬向风倾向有正贡献, 在上平流层, 其量值大小与参数化的重力波强迫相当.以上结果提供了对QBO形成机制以及模式模拟差异可能原因的认识.
