Interconnections between combined Length-of-Day and polar motion parameters concerning joint atmosphere-ocean-hydrosphere modes

该项目研究气候变率/气候变化与地球自转参数（ERPs）在年际至年代际时间尺度上的相互关系。在何种程度上，erp可以作为一个独立于大气和海洋测量的气候指标来使用。为了实现这一目标，结合了两种方法：一方面，考虑到两个子系统中变率模式的相互依赖性，分析了大气-海洋系统中动力过程对erp的影响。另一方面，ERP变化是根据海洋-大气系统的特定变化预估的。研究了不同的模式（如ENSO、NAO）及其在大气和海洋中的相互关系和潜在过程。虽然大气的贡献可以从大气再分析产品中估计出来，但海洋的影响不能从三维观测中推断出来。因此，采用了由大气资料强迫的全球海洋数值模式。耦合的大气-海洋模式用于估计气候系统的长期变化对erp变化的贡献。

The project investigates the interrelation of climate variability/climate change and the variations in the Earth Rotation Parameters (ERPs) on interannual to decadal time scales. The extent is determined to which ERPs can be used as a climate indicator which is independent of measurements in the atmosphere and the ocean. Two approaches are combined to achieve this goal: On the one hand, the impact of dynamical processes in the atmosphere-ocean system on ERPs is analysed, taking into account the interdependence of the variability patterns in the two sub-systems. On the other hand, the ERP variations are projected on specific variations in the ocean-atmosphere system. Different patterns (like ENSO, NAO), their interrelation and underlying processes in atmosphere and ocean are investigated. While atmospheric contributions can be estimated from atmospheric reanalysis products the impact of the ocean cannot be deduced from three-dimensional observations. Thus, numerical global ocean models forced by atmospheric data are used. Coupled atmosphere-ocean models are employed for estimating the contribution of long term variations in the climate system to variations of the ERPs.