Waves in the Lower Atmosphere

低层大气中的波浪

• 批准号: 9422869
• 负责人: George Chimonas
• 金额: $ 22.06万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-09-15 至 1999-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9422869&HistoricalAwards=false
• 关键词: Waves; Lower; Atmosphere

The object of this research is to explore how wavelike disturbances are created in the lower atmosphere, how these waves contribute to turbulence and mixing, and how these waves influence the location of severe weather events such as storms and squall lines. The waves of intent are gravity waves, ordered disturbances with wavelengths ranging from a few hundred meters to many hundreds of kilometers, and periods ranging from a few minutes to large fractions of a day. The scales of these waves and some other physical characteristics allow them to interact strongly with meteorological systems such as storms, gusts, squall lines, and the turbulence that leads to atmospheric mixing. The importance of these waves in meteorology has been recognized since the 1950's, but the challenge of learning how to apply the wave theory to practical situations remains. The wave theory itself is still incomplete, particularly with respect to the origin of many of the waves and how they behave when they reach large amplitudes. This proposal studies a wave generation mechanism that receives attention in engineering applications, but has been rather neglected in meteorology, Jeffreys' drag mechanism. The mechanism originates with the friction that a fluid experiences as it moves over a rough surface - in the meteorological context, the surface of the earth. The disparate natures of the forces that drive the motion of the fluid and the surface forces that oppose the flow can result in a breakdown of basic flows parallel to the surface: wavelike disturbances appear in the flow, extracting energy from the forces that drive the motion. Previous studies of this process suggest that it may be very effective in producing the atmospheric waves that break to produce mixing and turbulence. The studies also indicate that the process contributes to the strong, larger-scale waves associated with bands of severe weather. The theory will be developed further and used to interpret particular meteorological events, prob ably in the Southeast.

这项研究的目的是探索低层大气中如何产生波状扰动，这些波如何促成湍流和混合，以及这些波如何影响风暴和飑线等恶劣天气事件的位置。 意图波是重力波，是波长从几百米到数百公里不等的有序扰动，周期从几分钟到一天的大部分时间不等。 这些波的规模和其他一些物理特征使它们能够与风暴、阵风、飑线和导致大气混合的湍流等气象系统发生强烈的相互作用。 自 20 世纪 50 年代以来，人们就认识到这些波浪在气象学中的重要性，但学习如何将波浪理论应用于实际情况的挑战仍然存在。 波动理论本身仍然不完整，特别是关于许多波的起源以及它们在达到大振幅时的行为方式。 该提案研究了一种在工程应用中受到关注但在气象学中却被相当忽视的波浪产生机制，即杰弗里斯的阻力机制。 该机制源于流体在粗糙表面（在气象背景下，即地球表面）上移动时所经历的摩擦。 驱动流体运动的力和反对流动的表面力的不同性质可能会导致平行于表面的基本流动的破坏：流动中出现波状扰动，从驱动运动的力中提取能量。 先前对这一过程的研究表明，它可能非常有效地产生大气波，大气波破裂后会产生混合和湍流。 研究还表明，这一过程导致了与恶劣天气带相关的强烈、大规模的波浪。 该理论将得到进一步发展，并用于解释特定的气象事件，可能是在东南部。