Dynamics of the Shallow Meridional Circulation in the Tropical Eastern Pacific

热带东太平洋经向环流被普遍接受的观点是一个由热带辐合带深部对流加热驱动的深翻转单体，类似于纬向平均Hadley环流。然而，最近从野外活动中对大气的观察对这种观点提出了质疑。在几个独立的数据集中，观测到热带辐合带区域有明显的经向回流，但不仅在高海拔地区，而且在大气边界层上方的低海拔地区也有。这种浅层回流的原因和动力学将通过理论模型和高分辨率三维数值模拟进行研究。通过剪切驱动夹带，探讨浅层回流与大气边界层的相互作用。该项目将导致对热带环流和气候的新认识，因为观测和初步数值模拟表明，这种浅层回流等于或大于高空回流。

The generally accepted view of the meridional circulation in the tropical Eastern Pacific is one of a deep overturning cell driven by deep convective heating in the inter-tropical convergence zone, similar to the zonal mean Hadley circulation. However, recent observations of the atmosphere from a field campaign have called this view into question. In several independent data sets, a significant meridional return flow out of the region of the inter-tropical convergence zone was observed, but not only at high altitudes, but at low altitudes just above the atmospheric boundary layer. The causes and dynamics of this shallow return flow will be investigated with theoretical models and high-resolution three-dimensional numerical modeling. The interaction of the shallow return flow with the atmospheric boundary layer through shear-driven entrainment will be explored. The project will lead to new insights into tropical circulation and climate, as observations and preliminary numerical modeling suggest that this shallow return flow is equal or greater than that at high altitude.