Large-scale diurnal variability in the oceans: observation, modelling, assimilation and effects

地球表面的三分之二以上被海洋覆盖。海洋的现状以及它将如何演变对天气预报和海洋活动具有实际意义。对海洋状态的“分析”是利用对海洋的现有观测数据来创建给定时间的最佳海洋图像的过程。海洋表面温度(简称SST)是描述海洋的重要参数之一，由有限数量的船舶和浮标以及全球卫星观测。一个复杂的问题是，在SST中有一个每日信号，因为近地表因阳光加热而变暖，然后随着太阳下山而再次变冷。目前，在海洋和天气模拟中，这种影响在很大程度上被忽视了，部分原因是没有对大片海洋上从一小时到一小时发生的现象进行足够的观测。在这个项目中，我们将使用新的每小时卫星观测海洋表面的每日变暖和变冷，以及阳光加热的量来做几件事。第一件事是描述不同海洋区域在不同月份发生重大每日变暖事件的规模和频率。其次，我们将探索在进行SST分析时(使用英国气象局的新分析系统)如何对卫星SST进行每日变暖事件的校正。第三，我们将验证我们是否能够基于每日供暖事件的物理原理运行计算机模拟，从而对其规模做出良好的估计。第四，我们将计算每日变化对大气和海洋之间二氧化碳交换的重要性(除其他因素外，二氧化碳交换对SST很敏感)。最后，我们将进行一个案例研究，研究如何利用新的卫星观测来改进SST分析，使其首次捕捉到每日变暖。

More than two-thirds of the Earth's surface is covered by ocean. The current state of the ocean and how it will evolve is of practical importance to weather forecasting and maritime activities. 'Analysis' of the ocean state is the process of using available observations of the ocean to create the best possible picture of the ocean at a given time. The temperature of the surface of the ocean (referred to as SST) is one of the important parameters describing the ocean, and is observed by a limited number of ships and buoys and globally by satellites. One complication is that there is a daily signal in the SST as the near-surface warms in response to heating by sunlight and then cools again as the sun goes down. At present in ocean and weather simulations, this effect is largely ignored, partly because adequate observations of the phenomenon occuring from hour to hour through the day over large areas of ocean have not been available. In this project, we will use new hourly satellite observations of the daily warming and cooling of the ocean surface and of the amount of heating by sunlight to do several things. The first thing is to describe the size and frequency of significant daily warming events in different areas of oceans in different months. Second, we will explore how to correct satellite SSTs for daily warming events when doing SST analysis (using a new analysis system at the UK Met Office). Third, we will verify that we are able to run computer simulations based on the physics of daily heating events that give good estimates of their size. Fourth, we will calculate the importance of the daily variability to the exchange of carbon dioxide between the air and sea (which is sensitive to SST amongst other things). Lastly, we will conduct a case study of how to use the new satellite observations to improve SST analyses such that they capture daily warming for the first time.