Collaborative Research: Effects of Thermospheric Winds on Equatorial Spread-F

地球的电离层是地球表面以上50英里处的一层大气层，带电粒子的浓度相对较高。地球上的远距离无线电通信依赖于这一层反射的无线电波；卫星和地面站之间的通信依赖于穿过这一层的无线电波。这种无线电通信的质量在很大程度上取决于电离层中带电粒子的密度。当密度变化较大时，无线电波的传播就会受到干扰。低纬度地区的这种大密度变化被称为赤道等离子体气泡（EPBs），它通常是在太阳辐射日变化和大气风的共同影响下产生的。这些气泡是如何与大气风的变化相关联的是一个基本的科学问题，对它的理解可以更好地预测这些气泡何时何地形成，并有助于减轻它们造成的干扰。本项目的目的是通过观测和模拟研究热层中性风与赤道扩散F （ESF）之间的关系，ESF是雷达探测到气泡的一种表现形式。要解决的基本科学问题是：中性风的日常变化如何促进epb的发生和演变？本文将收集低纬度地区热层中性风和epb的多年观测资料，用于确定风与ESF/闪烁之间的关系。这些数据将有助于监测ESF的发展和演变，并提供对短期（每小时、每天）和长期（季节性）过程及其潜在物理特性的深入了解。此外，SAMI3 （SAMI3也是电离层模型）电离层模型将用于捕获与不同热层条件相关的电离层动力学，以确定各种情景如何产生epb /ESF，以及它们如何在短（日）和长（季节）时间段内演变。SAMI3模型是全面的，能够解决其他模型无法解决的重要问题。数据和建模的结合将导致对epb和ESF背后的动态过程有更深入的了解。从长期来看，地面中性风观测可用于预测ESF发生的可能性，预测闪烁的发生时间及其随时间的演变特征。能够从地面传感器预测和表征ESF/闪烁对于民用和国家安全目的至关重要。闪烁影响频率高达几GHz的跨电离层无线电信号，因此可能对以下系统产生有害影响：a)用于通信、定位、导航和授时的卫星系统。b)民用和国家安全垂直和倾斜（地平线以上）雷达系统。c)需要观测跨电离层无线电信号的科学仪器（如射电天文学）。这项研究的所有软件和数据都将公开。支持学生和学者使用模型和数据集重现和推进研究结果。JHU/APL将为高中生、本科生和研究生提供内部参与，帮助他们获得研究、教育和专业发展经验。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The Earth’s ionosphere is a layer of atmosphere starting at about 50 miles above the surface of the Earth with relatively high concentration of charged particles. Long-distance radio communications on Earth rely on reflection of radio waves by this layer; communications between satellites and ground stations rely on radio waves passing through this layer. The quality of such radio communications highly depends on density of charged particles in the ionosphere. When there is large variation of the density, radio wave propagation could be disrupted. One such large density variation at low latitudes is known as equatorial plasma bubbles (EPBs), which are often created under the combined influence of diurnal change of solar radiation and the atmosphere wind. How these bubbles are related to the change of atmospheric wind is a fundamental science question and its understanding could lead to better prediction of when and where these bubbles may form and help to mitigate the interruptions they create.The purpose of this project is to employ observations and modeling to investigate the relationship between thermospheric neutral winds and equatorial spread F (ESF), which is a manifestation of bubbles when detected by radars. The fundamental science question to be addressed is: How does the day-to-day variability of neutral winds contribute to the onset and evolution of EPBs? A multi-year observational data of concurrent thermospheric neutral winds and EPBs in the low latitudes will be developed and used to determine the relationships between winds and ESF/scintillation. The data will enable monitoring of the development and evolution of ESF and provide a deep insight into both the short-term (hourly, diurnal) and long-term (seasonal) processes and the underlying physics. Additionally, the SAMI3 (Sami3 is Also a Model of the Ionosphere) ionosphere model will be used to capture the ionospheric dynamics associated with different thermospheric conditions, to allow determination of how various scenarios give rise to EPBs/ESF and how they evolve over short (diurnal) and long (seasonal) time periods. The SAMI3 model is comprehensive and capable of addressing important problems in aeronomy that are not accessible with other models. The combination of the data and modeling will lead to a fundamentally deeper understanding of the dynamical processes underlying EPBs and ESF. Over the long term, the ground-based neutral wind observations could be used to forecast the likelihood of ESF and predict the onset of scintillation and characterize its evolution with time. Being able to predict and characterize ESF/scintillation from ground-based sensors is critical for operational civilian and national security purposes. Scintillation affects trans-ionospheric radio signals up to a few GHz in frequency and as such can have detrimental impacts on systems such as: a) Satellite-based systems that are used for communications, positioning, navigation and timing. b) Both civil and national security vertical and oblique (over the horizon) radar systems. c) Scientific instruments requiring observations of trans-ionospheric radio signals (e.g., radio astronomy). All the software and data from this research will be made publicly available. Support will be provided to students and academics who may want to reproduce and advance the findings using the models and the datasets. JHU/APL will provide in-house participation of high-school, undergraduate, and graduate students to help them get research, education, and professional development experience.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.