Predictability of Forced, Dissipated and Bounded AtmospheresFor Global, Synoptic, and Mesoscales

全球、天气和中尺度的强迫、耗散和有界大气的可预测性

• 批准号: 9014650
• 负责人: Jan Paegle
• 金额: $ 25.58万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-01-15 至 1994-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9014650&HistoricalAwards=false
• 关键词: Predictability; Forced; Dissipated; Bounded; AtmospheresFor

In a classic 1969 paper, Lorenz proved that the predictability in a simple (frictionless and unheated) model of the earth's atmosphere was, in principle, limited to about five days. Specifically, this meant that the forecast error would exceed the variability (say of wind, or pressure) on the actual map at the verification time of the forecast, after some forecast period. A better model and/or a more complete and accurate set of observations at initial time might reach this time of "useless" forecasts later, but even the best combination of these would have to reach it in about five days. The predictability, by this measure, in an actual operational forecast model now used in the ECMWF has gone from five days in 1980 to eight days in 1990. This operational model does include the effects of heating, and frictional and topographic interference with the flow caused by the earth's surface. With these complications it is not amenable to the type of theoretical treatment used by Lorenz. However, it is possible that precisely these complicating processes somehow enhance the predictability of the operational model. Thus the time limit on useful forecasts has yet to be determined, and ways to enhance the predictability deserve extended exploration. The objective of the research supported under this award is to estimate the attainable enhancement of predictability by: i) Improving the model's treatment of the larger-scale flow components, which have the most obvious forecast errors, and which are most directly linked to pole to equator and continent- ocean contrasts in heating and frictional/topographic interference; ii) Fitting a research version of the model with more detailed formulas for the calculation of momentum, heat, and water exchanges with the underlaying surface, and iii) Studying the sensitivity of the global-scale forecast error growth rate to simulated observational errors in selected regions which are presumed to require fine mesh specification of the initial state. The PI's prior research in Numerical Weather Prediction,and tropical, boundary layer, and mountain meteorology is especially relevant to the proposed work. These studies will increase our understanding of the factors affecting predictability, and are likely to contribute to further improvements in Numerical Weather Prediction over the next decade.

在 1969 年的一篇经典论文中，洛伦兹证明了地球大气的简单（无摩擦且未加热）模型的可预测性原则上仅限于大约五天。 具体来说，这意味着在某个预测期之后，在预测验证时，预测误差将超过实际地图上的变化（例如风或压力）。 更好的模型和/或更完整和准确的初始观测集可能会在以后达到“无用”预测的时间，但即使是这些的最佳组合也必须在大约五天内达到这一目标。通过这种衡量，ECMWF 现在使用的实际运行预测模型的可预测性已从 1980 年的 5 天增加到 1990 年的 8 天。该运行模型确实包括加热的影响以及对流动造成的摩擦和地形干扰。由地球表面。 由于这些并发症，它不适合洛伦兹使用的理论治疗类型。 然而，正是这些复杂的过程有可能在某种程度上增强了操作模型的可预测性。 因此，有用预测的时限尚未确定，增强预测能力的方法值得进一步探索。 该奖项支持的研究目的是通过以下方式估计可实现的可预测性增强： i) 改进模型对较大规模流动成分的处理，这些成分具有最明显的预测误差，并且与极点最直接相关。赤道和大陆-海洋在加热和摩擦/地形干扰方面的对比； ii) 使用更详细的公式拟合模型的研究版本，用于计算与下垫面的动量、热量和水交换，以及 iii) 研究全球尺度预测误差增长率对选定区域的模拟观测误差的敏感性假定需要初始状态的精细网格规范的区域。 PI 之前在数值天气预报以及热带、边界层和山地气象学方面的研究与拟议的工作特别相关。 这些研究将增加我们对影响可预测性的因素的理解，并可能有助于未来十年数值天气预报的进一步改进。