Improvement of Mid-Latitude Atmospheric Predictions Using Coherent Tropical Convective Phenomena

利用相干热带对流现象改进中纬度大气预测

• 批准号: 0806721
• 负责人: Richard Kleeman
• 金额: $ 33.88万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0806721&HistoricalAwards=false
• 关键词: Improvement; Mid; Latitude; Atmospheric; Predictions

The depiction of mid-latitude variability in the present generation of numerical weather prediction models is very good; there remain, however, significant problems in the depiction of tropical variability due to the need to parameterize convection. Through global atmospheric teleconnections, the tropics can significantly influence the mid-latitudes. It is reasonable, therefore, to expect that improvements in the depiction of long time-scale coherent phenomena within the tropics may benefit mid-latitude predictions. This follows because such variability has large spatial scales and long decorrelation times. It can induce a significant and long lasting influence on the higher latitudes and thus can affect long-range weather forecasts. In recent years, the availability of high quality tropical data has revealed that the depiction of such coherent variability is less than satisfactory in many numerical weather prediction and climate models. There are thus strong grounds for optimism that better simulation of tropical coherent phenomena may lead to improved mid-latitude forecasts. Motivated by these considerations, a stochastic model of the more important aspects of tropical convection will be developed. This model will be capable of reproducing well most of the important observed spectral features of convection in wave-number and frequency space and the horizontal and vertical spatial structures associated with coherent tropical variability. The stochastic model will be embedded within a (dry) primitive equation model, and the influence on mid-latitude predictions will be explored using a theoretical ensemble approach and by examining the influence on historical forecast skill. These predictability results will be compared with a primitive equation model that uses a conventional convection scheme. The theoretical study will address the following questions: 1. Which remote regions predictability are most strongly influenced by various tropical coherencies and why? 2. What is the principal dynamical mechanism in the atmosphere for causing shifts in predictability? The practical forecast study will address the following questions 1. How much gain in forecast skill might we expect in various regions with a better representation of tropical coherent variability? 2. How should effort be concentrated in improving convection representation to obtain the greatest payoff in increased prediction skill? Broader impacts of this work are educational and operational: Graduate students at the Courant Institute of New York University will be trained in important aspects of predictability research. Secondly this work will provide concrete information to operational weather prediction modelers as to what features of convective behavior should be addressed in order to obtain significant gains in forecast skill.

在这一代数值天气预报模式中，对中纬度变率的描述是非常好的;然而，由于需要对对流进行参数化，在对热带变率的描述方面仍然存在重大问题。通过全球大气遥相关，热带可以显著影响中纬度地区。因此，我们有理由期望，在热带地区描述长时间尺度相干现象方面的改进可能有利于中纬度地区的预报。这是因为这种变化具有大的空间尺度和长的去相关时间。它可以对高纬度地区产生重大而持久的影响，从而影响长期天气预报。近年来，高质量的热带资料的可用性表明，这种一致的变化的描述是不令人满意的，在许多数值天气预报和气候模式。因此，有充分的理由乐观地认为，对热带相干现象进行更好的模拟可能会改善中纬度的预报。出于这些考虑，一个随机模式的热带对流的更重要的方面将被开发。该模式将能够很好地再现波数和频率空间中观测到的对流的大多数重要谱特征以及与相干热带变率相关的水平和垂直空间结构。 随机模型将嵌入一个（干）原始方程模型，并将探讨中纬度预测的影响，使用理论合奏的方法，并通过检查历史预测技能的影响。这些可预测性的结果将与使用传统对流方案的原始方程模式进行比较。本文的理论研究将解决以下问题：1.哪些偏远地区的可预报性受各种热带相干性的影响最大，为什么？2.大气中导致可预测性变化的主要动力机制是什么？实际预测研究将解决以下问题1.在更好地代表热带相干变率的各个地区，我们期望在预报技巧上有多大的收获？2.应该如何集中精力改进对流表示，以便在提高预报技巧方面获得最大的回报？这项工作的更广泛影响是教育和业务：纽约大学柯朗研究所的研究生将接受可预测性研究重要方面的培训。其次，这项工作将提供具体的信息，业务天气预报建模的对流行为的功能应加以解决，以获得显着的收益，在预报技巧。