Towards a quantification of vortex impact on the arctic lowermost stratosphere

极地最下层平流层的特征是来自涡旋的非绝热下沉、中纬度平流层的向下输送以及来自低纬度的混合，这是布鲁尔-多布森环流下层分支的一部分。在较低的高度，穿过温带对流层顶的混合也有助于形成温带过渡层（ExTL）。在北半球，由于动力条件的年际变率引起的相当大的变率导致北极LMS组成的年际高变率。在这个建议中，我们想量化主要水库的贡献。我们将在不同示踪剂的快速（1-3Hz）机载测量的基础上做到这一点。我们将使用新增加的乙烷（C2H6）作为老化涡旋空气的指标。结合N2O、CO建立预算，推断相关气源区的相对贡献，量化涡旋空气对平流层最下层的影响。我们将进一步确定构成ExTL的对流层部分的影响，并比较不同年份（2015/2016冬季）和南半球（SOUTHTRAC）的ExTL垂直范围，以推断不同动力条件下ExTL深度的变化信息。最后，我们将研究前涡旋细丝与最下层平流层背景的相互作用。我们将特别关注受强切变或重力波活动通过区域影响的细丝，这两种情况都会导致动力不稳定和湍流。我们将研究这些细丝与周围空气之间的混合，并推断此类事件的示踪剂通量。

The lowermost stratosphere of the polar regions is charecterized by diabatic downwelling from the vortex, downward transport in mid latitude stratosphere and mixing from low latitudes as part of the lower branch of the Brewer-Dobson circulation. In lower altitude mixing across the extratropical tropopause additionally contributes leading to the formation of the extratropical transition layer (ExTL). In the northern hemisphere a considerable variability due to the intraannual variability of the dynamical conditions leads to a high interannual variability of the arctic LMS composition. In this proposal we want to quantify the contribution of the main reservoirs. We will do this on the basis of fast (1-3Hz) airborne measurements of different tracers. We will use the newly added species ethane (C2H6) as an indicator for aged vortex air. Combined with N2O, CO we set up a budget to infer the relative contributions from the relevant source regions of air to qunatify the impact of vortex air on the lowermost stratosphere. We will further determine the impact of the tropospheric fraction constituting the ExTL and compare the vertical extent of the ExTL for different years (winter 2015/2016) and the southern hemisphere (SOUTHTRAC) to infer information about the variability of the ExTL depths under different dynamical conditions. Finally we will study the interaction of former vortex filaments with the lowermost stratospheric background. We will specifically focus on filaments subject to strong shear or passing regions of gravity wave activity, which both my lead to dynamical instability and turbulence. We will study mixing between these filaments and the surrounding air and infer tracer fluxes for such events.