Searching for Upper Atmospheric Waves at the Edge of Space (SURGE)

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Atmospheric modelling is entering a new era of whole-atmosphere models which extend from the surface to space. These models will provide significant societal benefit, improving both terrestrial and space-weather predictions and forecasts of processes as diverse as long-term surface climate change, satellite orbital drag and GNSS & radio disruptions. However, these new models currently fail to simulate fundamental circulations of the middle and upper atmosphere. This dramatically inhibits their ability to couple these layers together and simulate the atmosphere as one. For example, in one leading climate model, the winds in polar mesosphere and lower thermosphere (between 80-110km) are not only the wrong speed, but they blow in the wrong direction for half the year compared to observations. This problem is widespread, affecting nearly all vertically-extended atmospheric models including the Met Office Extended Unified Model (ExUM), and is as a major impediment to realising the vision of whole-atmospheric modelling. This bias occurs because nearly all global models have inaccurate representations of a fundamental component of the atmospheric circulation: atmospheric gravity waves (GWs). Atmospheric GWs transport energy and momentum throughout the atmosphere and are responsible for driving many large scale circulations in the middle atmosphere. More importantly for the middle and upper atmosphere, these models have no representation at all of secondary gravity waves (2GWs), which are generated when primary GWs break, like ocean waves crashing on a beach. These cascades of 2GWs can transport momentum in very different ways to the primary GWs that generated them, and recent theoretical work has shown that these waves are essential to achieving realistic circulations in the middle and upper atmosphere. There is therefore a critical needs to observe, measure and understand 2GWs throughout the middle and upper atmosphere globally, such that they can be represented in the next generation of whole-atmosphere climate models and achieve realistic atmospheric forecasts from the surface to the edge of space. In SURGE, I will use a sophisticated suite of global observations and state-of-the-art models to detect, measure and simulate 2GWs throughout the middle and upper atmosphere and test how they can be represented in next generation whole-atmosphere models. This will complete the fundamental knowledge gap crucial for realising accurate atmospheric forecasts from the surface to space.