A ship-borne imager: determining mesospheric gravity wave activity above the ocean

重力波是大气中的浮力波。它们可以从各种来源产生，例如流过山脉或大型天气系统的风。当它们向上传播时，它们变得不稳定并破裂（类似于海滩上的波浪），沉积它们的能量和动量，驱动大气中的环流和温度模式。高度在50公里到90公里之间的区域，被称为中间层，主要是重力波活动。为了在大气气候模型中准确地再现它们的影响，我们需要从地球的所有地区观测重力波（并确定其来源）。由于海洋占地球表面的70%，因此了解海洋上发生的重力波活动至关重要。 传统上，卫星观测用于获得大气中重力波活动的全球估计，但它们具有局限性，因为它们不能看到重力波的整个范围（全谱）。这项提议旨在完成船载成像仪的开发，该成像仪将允许从R.R.S.进行中间层的重力波测量。詹姆斯克拉克罗斯，因为它穿越大西洋，并从南极和英国。这些测量将提供对重力波范围的不同部分的独特见解，卫星可以观察到，船载成像仪将使用一个新的系统，3个1度视场成像仪（辐射计）和船舶的俯仰和横摇扫描天空。成像仪将在大约90公里的高度观测气辉层中的重力波扰动。气辉是指大气中不同气体层发出的微弱光。当重力波穿过气辉层时，它们交替地压缩和稀薄它，导致气辉发射的变化。利用这些观测结果可以确定重力波的特征，我们建议利用船舶与陆基重力波源的隔离和船舶行程进行案例研究，并研究两种对中间层重力波场的影响：深海大天气系统和地形。

Gravity waves are buoyancy waves in the atmosphere. They can be produced from a variety of sources, e.g. wind flowing over mountains or large weather systems. As they propagate upwards they become unstable and break (similar to waves on a beach) depositing their energy and momentum, driving the circulation and temperature patterns in the atmosphere. The region between 50km and 90km in altitude, known as the mesosphere, is dominated by gravity wave activity. In order to accurately reproduce their effects in atmospheric climate models, we need to observe gravity waves (and identify their sources) from all areas of the planet. As the oceans make up 70% of the Earth's surface it is vitally important to understand the gravity wave activity that occurs over them. Traditionally satellite observations are used to obtain global estimates of gravity wave activity in the atmosphere but, they have limitations in that they cannot view the whole range (full spectrum) of gravity waves. This proposal looks to finalise development of a ship-borne imager that will allow gravity wave measurements of the mesosphere to be made from the R.R.S. James Clarke Ross as it traverses the Atlantic Ocean to and from the Antarctic and the U.K. These measurements will provide a unique insight into a different section of the gravity wave range to that which satellites can observe.The ship-borne imager will use a novel system of 3 one-degree field of view imagers (radiometers) and the pitch and roll of the ship to scan the sky. The imagers will be observing gravity wave perturbations in a layer of airglow at around 90km altitude. Airglow is the term given to the weak emission of light by different gas layers in the atmosphere. As gravity waves pass through this airglow layer they alternately compress and rarefy it, resulting in a variation in the airglow emissions. Using these observations it is possible to determine the characteristics of the gravity waves.We propose to exploit the ships isolation from land-based gravity wave sources and the ships itineraries to do case studies and examine two influences on the mesospheric gravity wave field: large weather systems in the deep ocean and topography.