Some considerations on the spectral features of meridional heat transport by transient eddies
Some considerations on the spectral features of meridional heat transport by transient eddies
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DOI：
10.1002/qj.2224
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发表时间：
2014-04-01
影响因子：
8.9
通讯作者：
Czaja, A.
中科院分区：
文献类型：
--
作者：
Messori, G.;Czaja, A.
本研究分析了时频域中瞬态涡流引起的经向大气热传输中的极端事件。使用的数据是欧洲中期天气预报中心 (ECMWF) ERA-中期再分析数据，气压为 850 mb，每日纬度和经度分辨率为 0.7 度。快速增长的大气模式与大量的热传输相关，这表明传输极端值与不断增长的斜压系统（此处定义为 2.5-6 天范围内的运动）之间存在联系。然而，通过分析输运极值以及相应的经向速度和湿静态能量时间异常的小波功率谱，发现情况并非如此。事实上，斜压系统对极端热传输事件谱的综合功率仅提供有限的贡献。传输极端是由速度和潮湿静态能量异常之间非常精确的相位和相干关系驱动的，作用于广泛的频率范围（2.5-30天）。周期超过 6 天的行星尺度运动 (k = 0-4) 在此框架中发挥着关键作用。
The present study analyses extreme events inmeridional atmospheric heat transport due to transient eddies in the time-frequency domain. The data used are the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis data, at the 850 mb pressure level and with daily, 0.7 degrees latitude and longitude resolution. Fast-growing atmospheric modes are associated with large heat transport, which would suggest a link between transport extremes and growing baroclinic systems (defined here as motions in the 2.5-6 day band). However, by analyzing wavelet power spectra of transport extremes and of the corresponding meridional velocity and moist static energy temporal anomalies, this is found not to be the case. In fact, baroclinic systems provide only a modest contribution to the integrated power of the extreme heat transport event spectrum. The transport extremes are driven by very precise phase and coherence relationships between the velocity and moist static energy anomalies, acting over a broad range of frequencies (2.5-30 days). Planetary-scale motions (k = 0-4) with periods beyond 6 days play a key role in this framework.