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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >The stratospheric quasi-biennial oscillation in the NCEP reanalyses: Climatological structures
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The stratospheric quasi-biennial oscillation in the NCEP reanalyses: Climatological structures

机译：NCEP的平流层准两年一次振荡重新分析：气候学结构

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Global quasi-biennial variation in the lower stratosphere and tropopause region is studied using 41 years (1958-1998) of reanalyses from the National Centers for Environmental Prediction (NCEP). Horizontal wind, temperature, geopotential height, tropopause temperature and pressure fields are used. A new quasi-biennial oscillation (QBO) indexing method is presented, which is based on the zonal mean zonal wind shear anomaly at the equator and is compared to the Singapore index. A phase difference compositing technique provides ''snapshots" of the QBO meridional-vertical structure as it descends, and "composite phases': provide a look at its time progression. Via binning large amounts of data, the first observation-based estimate of the QBO meridional circulation is obtained. High-latitude QBO variability supports previous studies that invoke planetary wave-mean flow interaction as an explanation. The meridional distribution of the range in QBO zonal wind is compared with the stratospheric annual cycle, with the annual cycle dominating poleward of similar to 12 degrees latitude but still being significant in the deep tropics. The issues of temporal shear zone asymmetries and phase locking with the annual cycle are critically examined. Subtracting the time mean and annual cycle removes similar to2/3 of the asymmetry in wind land wind shear) zone descent rate. The NCEP data validate previous findings that both the easterly and westerly QBO anomalous wind regimes in the lower stratosphere change sign preferentially during northern summer. It is noteworthy that the NCEP QBO amplitude and the relationships among the reanalyzed zonal wind, temperature, and meridional circulation undergo a substantial change around 1978. [References: 72]
机译：使用国家环境预测中心（NCEP）进行的41年（1958-1998年）再分析研究了平流层下部和对流层顶区域的全球准双年度变化。使用水平风，温度，地势高度，对流层顶温度和压力场。提出了一种新的准双年度振荡（QBO）索引方法，该方法基于赤道上的纬向平均纬向风切变异常，并与新加坡指数进行了比较。相位差合成技术在QBO子午垂直结构下降时提供“快照”，“合成相位”：提供其时间进度的信息。通过合并大量数据，获得了基于观测的QBO经络环流的第一个估计。高纬度QBO变异性支持先前的研究，这些研究援引行星波平均流相互作用作为解释。将QBO纬向风的经向分布与平流层的年周期进行了比较，其中年周期在纬向类似于12度纬度的极地上占主导地位，但在深热带地区仍然很重要。关键地研究了时间剪切带不对称和年周期锁相的问题。减去时间平均值和年周期，可以消除风场风切变区下降速率中不对称度的2/3。 NCEP数据证实了先前的发现，即平流层下层的东风和西风QBO异常风态在北部夏季均优先出现标志。值得注意的是，1978年前后，NCEP QBO振幅以及重新分析的纬向风，温度和子午环流之间的关系发生了重大变化。[参考文献：72]

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