Collaborative Research: Design of a Nanosat Constellation for Measuring Internal Gravity Wave Fluxes in the Earth's Stratosphere

点击翻译按钮获取中文摘要

Gravity waves, meaning waves for which buoyancy provides the restoring force, are commonly seen propagating across the surfaces of ponds and lakes, in the wakes of ships, and breaking in the surf zone at the beach. Similar waves occur in the atmosphere, but atmospheric gravity waves can propagate vertically as well as horizontally. Vertical propagation means that activity near the surface, such as winds blowing over mountains or updrafts in convective clouds, can influence the circulation at stratospheric levels. Stratospheric circulation can in turn affect surface weather over much of the globe, and is a potential source of long-range forecast skill. Thus the driving of the stratosphere by gravity waves is a topic of both practical and scientific interest.The goal of this project is to design a satellite constellation for observing atmospheric gravity waves. The constellation consists of nine low-cost cubesats using radio occultation (RO) to detect gravity waves in temperature profiles extending through the upper troposphere and lower stratosphere. RO is a technique which measures the refraction of signals from satellites of the Global Navigation Satellite System (GNSS, which includes the GPS satellites) as they pass through the atmosphere. At the levels of interest refraction can be used to deduce atmospheric temperature, thus the constellation would produce nine simultaneous temperature profiles, each containing wiggles indicating the presence of gravity waves. These could be combined to determine the three-dimensional structure of a wave packet, from which its propagation and likely influence on stratospheric circulation could be inferred. The project is a feasibility study in which the PIs use a high-resolution atmospheric model, the Model for Prediction Across Scales (MPAS, in a global nonhydrostatic configuration), to generate realistic vertically propagating gravity waves. A virtual constellation "orbits" over the model simulation to determine what observations would be produced by the satellites for a given wave field and a given set of satellite, orbit, and instrument characteristics.The work has societal relevance due to the desirability of better gravity wave representations in models used for weather prediction and to provide guidance to decision makers. In addition, the work contributes to the development of cubesat technology, which has a variety of commercial and scientific applications. Cubesats also provide valuable educational experiences, as they can be built and operated by university students. The project provides support and training to a graduate student, thereby promoting workforce development in this research area.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.