The role of uncertainty in waveguide perturbations on midlatitude predictability with DOWNSTREAM

这项建议的主要研究者将评估与气旋发展同时发生的急流结构变化是否是下游天气预报误差的重要来源。 这些事件可能会导致极端天气事件的预测不佳。 该项目将通过培训一名研究生掌握可预测性、数据同化和天气学/中尺度气象学的最先进方法，为美国未来的劳动力做出贡献。 一个成功的项目将发展的理解，可以导致改善天气预报，这一建议的目的是评估波导扰动与中纬度气旋和热带气旋（ET）向热带外转变有关的假设，是下游预测误差的重要来源。该建议的第一阶段涉及评估这一假设，通过比较中纬度气旋和ET发展后的下游可预测性，并将其与使用NOAA地球系统研究实验室第二代重新预报项目31年集合预报的可预测性气候学进行比较。此外，这项研究将评估假设中纬度与ET气旋的可预测性，以及这种可预测性如何根据波导扰动的大小而变化。此外，本研究将评估与波导扰动附近的流出和热力学剖面的不确定性如何影响下游可预测性相关的假设。将通过比较与下游状态相关的预测指标对流出的敏感性与预测指标对状态其他方面的敏感性，来评估流出对下游状态的作用。 外流的作用将通过进行一系列扰动初始条件实验来确认，其中修改了初始时间外流特性的各个方面，然后评估对下游状态的影响。

The principal investigator of this proposal will assess whether changes to the structure of the jet stream that occur in conjunction with the development of cyclones are significant sources of weather forecast errors further downstream. These events can result in poorly forecast extreme weather events. The project will contribute to the future US workforce through the training of a graduate student in state-of-the-art approaches to predictability, data assimilation, and synoptic/mesoscale meteorology. A successful project will develop understanding that can lead to improved weather forecasts, and in turn provide greater lead time for warnings and reduced loss of life and property due to certain mid-latitude extreme weather events.The goal of this proposal is to evaluate the hypothesis that waveguide perturbations associated with midlatitude cyclones and the extratropical transition of tropical cyclones (ET) are an important source of downstream forecast errors. The first phase of this proposal involves evaluating this hypothesis by comparing the downstream predictability following the development of midlatitude cyclones and ET and comparing it to a predictability climatology using 31 years of ensemble forecasts from the NOAA Earth System Research Laboratory 2nd generation reforecast project. Moreover, this study will evaluate hypotheses regarding the predictability of midlatitude vs. ET cyclones and how this predictability varies depending on the magnitude of the waveguide perturbation. In addition, this study will evaluate hypotheses related to how uncertainty in the outflow and thermodynamic profile in the vicinity of waveguide perturbations impact the downstream predictability. The role of the outflow on the downstream state will be evaluated by comparing the sensitivity of forecast metrics related to the downstream state to the outflow against the sensitivity of the forecast metrics to other aspects of the state. The role of the outflow will be confirmed by performing a series of perturbed initial condition experiments where aspects of the initial-time outflow properties are modified, and then evaluating the impact on the downstream state.