Modelling and parameterization of lead generated turbulence in the atmospheric boundary layer over Antarctic sea ice

在这个项目中，我们研究了在南极海冰的铅（渠道开放或薄冰覆盖）湍流大气过程。特别是在冬季，这种不均匀性在海冰覆盖产生强烈的湍流涡流影响大气边界层过程和空气冰相互作用的下游侧的铅的大气对流。由于这些过程的尺度非常小，它们必须在最先进的气候模型中进行参数化。尽管近年来在高分辨率模式和参数化方面取得了一些进展，但要全面了解铅对大气边界层湍流的影响，并为气候和天气预报模式提供可靠的参数化，仍有许多问题需要解决。这些问题涉及例如气象强迫、铅的几何形状、海冰地形和在铅上发展的小尺度有组织对流的影响。该项目分为三个部分，各有具体目标。第一个目标是更好地了解导线上的对流过程。为此，我们使用国家的最先进的大涡模拟（LES）的接近现实的大气对流过程的建模，并在封闭的环境中的铅。我们认为，例如，铅的几何形状和强迫参数对大气湍流的作用的影响，以及在铅的对流羽流的相互作用与加盖逆温及其对垂直夹带的影响。第一次验证这样的LES运行是可能的基础上，最近获得的飞机运动的观测数据。第二个目标是改善参数化的基础上的LES的结果，首先为微尺度大气非涡解模式，最后为气候模式的铅湍流。建模（LES和微尺度）和参数化工作将基于申请人以前的成功合作。这项新工作的目标是更复杂的情况和气候模式的参数化。估计铅影响的困难之一是难以从卫星上观察铅。因此，建模和参数化工作将得到基于高分辨率和中分辨率卫星传感器的遥感的支持（第三个目标）。该项目侧重于引线和小规模工艺，有助于实现SPP 1158的总体目标2.2.4，例如，重点关注对极地地区特别重要的当地影响，如冰穴和冰带对低层大气特征的影响。 我们申请资助两名博士生3年，一个用于目标（1）所涉及的工作，一个用于目标（2）。还需要为汉堡大学的学生助理提供资金（两年），以支持目标（3）所述的遥感工作。

In this project we investigate turbulent atmospheric processes over leads (channels either open or with thin ice cover) in Antarctic sea ice. Especially during winter such inhomogeneities in the sea ice cover generate atmospheric convection with strong turbulent eddies influencing atmospheric boundary layer processes and air ice interaction on the downstream side of leads. Due to the very small scales of these processes they have to be parameterized in state-of-the-art climate models. Although some progress has been achieved in recent years with both high resolution modeling and parameterization many questions need still to be solved to understand the impact of leads on atmospheric boundary layer turbulence in all aspects and to arrive at reliable parameterizations for climate and weather prediction models. These questions concern e.g. the impact of meteorological forcing, of lead geometry, of the sea ice topography, and of small scale organized convection developing over leads. The project is divided into three parts with specific goals. The first goal is to obtain a better understanding of convection processes over leads. To that aim we use state-of-the-art large eddy simulation (LES) for a close-to-reality modeling of atmospheric convection processes over and in the close environment of leads. We consider, for example, the impact of lead geometry and the role of forcing parameters on atmospheric turbulence, and the interaction of the convective plumes over leads with the capping inversion and its impact on vertical entrainment. For the first time a validation of such LES runs is possible on the basis of observed data recently obtained by an aircraft campaign. The second goal is to improve parameterizations of turbulence over leads based on the LES results first for microscale atmospheric non-eddy-resolving models and finally for climate models. Both the modeling (LES and microscale) and parameterization work will be based on previous successful cooperation of the applicants. The new work aims at more complex cases and towards the parameterization in climate models. One of the difficulties for an estimation of the lead impact consists in the difficulties to observe leads from satellite. Thus the modeling and parameterization work will be supported by remote sensing based on high and medium resolution satellite sensors (third goal). With its focus on leads and small scale processes this project contributes to the overarching goal 2.2.4 of the SPP 1158 which intends e.g., to put a strong focus on local impacts particularly important in the polar regions such as the influence of polynyas and leads on the characteristics of the lower atmosphere. We apply for the funding of two PhD students for 3 years, one for the work addressed by goal (1) and one for goal (2). Funding is also necessary for student assistants at University Hamburg (2 years) supporting the remote sensing work addressed in goal (3).