Improving Prediction of Fronts

一旦根据我们对大气当前状态的最佳估计来初始化天气模型，随着时间的推移，它将偏离大气的真实状态。单一确定性天气模式提供有用信息的时间段被称为“有用预报范围”，它提供了模型预测技能的衡量标准。例如，ECMWF的有用预测现在通常在7至10天之间。扩大天气预报的有用范围(并提高该范围内的准确度)将对社会和经济产生明显的惠益；惠益包括：能源管理、保护基础设施、协调灾害应对、农业规划、旅游和休闲产业规划、运输管理、确定对天气敏感的健康状况、水资源管理、改进商品市场决策、环境决策和自然资源管理。在这个项目中，我们将开发一种方法来理解当前预测技能的一些限制和有用的预测范围，并将研究消除这些限制的实用方法。这当然是一个巨大的话题；我们将把我们的研究限制在干动力核心(模型中预测风、温度和气压的部分)，并集中在一个重要的现象上，即锋面的演变，特别是由此产生的对大尺度大气环流的反馈。锋面在降水和许多恶劣天气事件的输送中起着关键作用，这些事件在上文讨论的所有社会经济领域都具有重要的控制作用。与锋面有关的挑战是，虽然与业务预报模式中两个网格点之间的距离相比，天气锋面一侧到另一侧的距离很小，但锋面对风速和风向以及锋面周围大片区域的气压有重大影响。该项目的目的是在动力核心设计方面找到改进，以改进对锋面附近的风和气压的预测。

Once a weathermodel has been initialised from our best estimate of the current stateof the atmosphere, it will diverge from the real state of theatmosphere over time. The period of time during which a singledeterministic weather model provides useful information is known asthe "useful forecast range'', which provides a measure of thepredictive skill of the model. For example, the ECMWF useful forecastrange is now typically between 7 and 10 days. Extending the useful forecast range of weatherforecasts (and improving accuracy over that range) would have clearbenefits to society and the economy; benefits include: energy management, protection ofinfrastructure, coordinating disaster response, agricultural planning,planning in travel and leisure industries, transportation management,targeting of weather-sensitive health conditions, water resourcemanagement, improved decision making in commodity markets,environmental decision making and natural resource management. In thisproject, we will develop a means of understanding of some currentlimitations to predictive skill and the useful forecast range, andwill investigate practical methodologies for removing them. This is ofcourse a huge topic; we shall restrict our investigation to the drydynamical core (the part of the model that predicts winds, temperatures and pressures), and concentrate on one important phenomena, namely theevolution of fronts and, in particular, the resulting feedback on the large scale atmospheric circulation. Fronts play a key role in the delivery ofprecipitation, and many severe weather events, which have an importantrole in all of the socioeconomic areas discussed above. The challenge associated with fronts is that although the distance from one side of a weather frontto another is very small compared to the distance between two grid points inan operational forecast model, fronts have a significant impact on the wind speedand direction as well as the pressure over a large region around the front. The aim of this projectis to find improvements in dynamical core design that can improve the predictionof the winds and pressures in the vicinity of fronts.