Stratosphere-Troposphere Coupling Studies

本研究的目的是探索平流层变率和平流层-对流层耦合，重点是平流层如何影响对流层。平流层似乎提供了全球（表面）变暖的早期证据，即观测到的平流层冷却。这种趋势在平流层被准两年一次振荡、太阳周期、火山爆发和内部动力学等影响所引起的年际变率所混淆。其中一种变率模式是北极涛动（AO），其气候影响与北大西洋涛动（NAO）非常相似，并表现出与平流层的强耦合。温室气体增加的模拟研究表明，平流层趋势可能通过垂直耦合放大或诱发对流层趋势。pi将(i)利用重新分析的NCEP和TOVS数据的客观分析技术来了解平流层环流异常倾向于向下传播到对流层的过程；（ii）检查南半球，特别是在晚春，看看是否可以看到同样的现象；（iii）调查和了解观测到的纬向风异常（在2-3个月的时间尺度上在平流层内）向极地和向下传播与AO向对流层向下传播（~ 3周时间尺度）之间的关系；（iv）研究纬向风的变率模式，以了解热带平流层上层纬向风异常（~30-50 km）与两个半球高纬环流异常之间的关系；(v)检查对流层上层和平流层下层的耦合模式，这些模式解释了从对流层到平流层的波活动通量。这项工作很重要，因为它将增加我们对平流层-对流层耦合机制的理解。这可能对气候的可预测性产生影响。

The objective this research is to explore stratospheric variability and stratosphere-troposphere coupling, with an emphasis on how the stratosphere influences the troposphere. The stratosphere appears to be providing early evidence of global (surface) warming, which is observed as stratospheric cooling. Such trends are obfuscated in the stratosphere by interannual variability resulting from influences such as the quasi-biennial oscillation (QBO), solar cycle, volcanic eruptions and internal dynamics. One such mode of variability, the Arctic Oscillation (AO) has climate impacts very similar to the North Atlantic Oscillation (NAO) and shows strong coupling to the stratosphere. Modeling studies with increased greenhouse gases show that stratospheric trends, may through vertical coupling, amplify or induce tropospheric trends. The PIs will (i) use objective analysis techniques with reanalyzed NCEP and TOVS data to understand the process by which stratospheric circulation anomalies tend to propagate downward into the troposphere;(ii) examine the Southern Hemisphere, especially in late spring, to see if the same phenomenon can be seen; (iii) investigate and understand the relationship between observed poleward and downward propagation of zonal wind anomalies (within the stratosphere on a time scale of 2-3 mo) and downward propagation of the AO to the troposphere (~ 3 week time scale);(iv) investigate modes of variability in zonal wind to understand the relationship between tropical upper stratospheric zonal wind anomalies (~30-50 km) and high-latitude circulation anomalies in both hemispheres;(v) examine coupled patterns in the upper troposphere and lower stratosphere that explain the flux of wave activity from the troposphere to the stratosphere. The work is important because it will increase our understanding of stratosphere-troposphere coupling mechanisms. This could have implications for climate predictability.