CEDAR: Resolving Thermosphere Response Times to Auroral and Solar Energy Inputs and Improving Neutral Density Predictions

CEDAR：解决热层对极光和太阳能输入的响应时间并改进中性密度预测

• 批准号: 2019465
• 负责人: Daniel Weimer
• 金额: $ 25.78万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2019465&HistoricalAwards=false
• 关键词: CEDAR; Resolving; Thermosphere; Response; Times

This project is to refine and enhance a new computer model that provides temperatures in the thermosphere (the atmosphere region from about 80 to 600 km above sea level). The temperature in the thermosphere varies in response to solar energy input and auroral events at high latitudes and is also closely related to the atmospheric density. This improved model will help better predict the atmospheric temperature and density in the thermosphere. Since the density is the key parameter that determines satellite drag, this improvement will help better predict satellite drag and space weather in response to changes in solar radiation and associated disturbances in Earth’s electromagnetic field.The new model is referred to with the acronym EXTEMPLAR, for EXospheric TEMperatures on a PoLyhedrAl gRid. The method relies on converting satellite density measurements into exospheric temperatures and sorting these values into bins based on their location on a geodesic grid. By fitting the data in each bin to the environmental conditions at the time, maps of the exospheric temperature can be obtained from the regression coefficients. These temperatures can be used to obtain neutral densities at any location and altitude, by substituting for the values in the empirical model of the thermosphere by the Naval Research Laboratory.Project activities include: (1) Measuring the time delays between auroral energy inputs and exospheric temperature response, and how these delays vary around the globe. (2) Investigating the occurrence of regions having decreasing density during major heating events. (3) Improving the modeling of the thermosphere's response to variable solar radiation. (4) Construction of an improved neutral density prediction model. (5) Validate the neutral density predictions with comparisons to measurements.The project has the potential to advance the knowledge and understanding of how the thermosphere responds on regional and global scales to energy that is transferred from both solar radiation and auroral electrodynamic heating. The timings between the energy input and the thermosphere's response will be established as a function of global coordinates. The development of methods using triangulated geodesic grids has the potential to transform modeling and analysis techniques within the space science community.The successful conclusion to this project will result in an empirical model that will be useful to other research in the scientific community, particularly those related to the objectives of the NSF CEDAR program, including simulations of the coupled, ionosphere/thermosphere system. The research has potential benefits to society at large, such as through better predictions of the variations in neutral mass density that can change the orbits of satellites. This capability is important to national security, the success of commercial space enterprises, as well as the safety of human spaceflight.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.

这个项目是为了改进和增强一个新的计算机模型，该模型可以提供热层（海拔约80至600公里的大气区域）的温度。在高纬度地区，热层温度随太阳能量输入和极光事件的变化而变化，并与大气密度密切相关。这种改进的模型将有助于更好地预测热层的大气温度和密度。由于密度是决定卫星阻力的关键参数，这一改进将有助于更好地预测卫星阻力和空间天气对太阳辐射和地球电磁场相关干扰变化的响应。新模型被称为首字母缩略词EXTEMPLAR，用于多面体网格上的外大气层温度。该方法依赖于将卫星密度测量值转换为外逸层温度，并根据它们在测地线网格上的位置将这些值分类到箱子中。通过将每个箱中的数据与当时的环境条件拟合，可以从回归系数中获得外逸层温度图。这些温度可以用来代替海军研究实验室的热层经验模型中的值，从而在任何位置和高度获得中性密度。项目活动包括：(1)测量极光能量输入与大气层温度响应之间的时间延迟，以及这些延迟在全球范围内的变化。(2)调查重大升温事件期间密度下降区域的发生情况。(3)改进热层对变太阳辐射响应的模拟。(4)构建改进的中性密度预测模型。(5)通过与测量值的比较来验证中性密度预测。该项目有可能促进对热层如何在区域和全球尺度上对来自太阳辐射和极光电动力加热转移的能量作出反应的认识和理解。能量输入和热层响应之间的时间将作为全球坐标的函数建立。使用三角测地线网格的方法的发展有可能改变空间科学界的建模和分析技术。该项目的成功结论将产生一个经验模型，该模型将对科学界的其他研究有用，特别是与NSF CEDAR计划目标相关的研究，包括耦合电离层/热层系统的模拟。这项研究对整个社会都有潜在的好处，比如可以更好地预测中性质量密度的变化，从而改变卫星的轨道。这种能力对国家安全、商业航天企业的成功以及人类航天飞行的安全都很重要。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。

项目成果

Global Variations in the Time Delays Between Polar Ionospheric Heating and the Neutral Density Response

极地电离层加热与中性密度响应之间时滞的全球变化

• DOI: 10.1029/2022sw003410
• 发表时间: 2023
• 期刊: Space Weather
• 影响因子: 3.7
• 作者: Weimer, Daniel R.;Mehta, Piyush M.;Licata, R. J.;Tobiska, W. K.
• 通讯作者: Tobiska, W. K.

Comparison of a Neutral Density Model With the SET HASDM Density Database

中性密度模型与 SET HASDM 密度数据库的比较

• DOI: 10.1029/2021sw002888
• 发表时间: 2021
• 期刊: Space Weather
• 影响因子: 3.7
• 作者: Weimer, Daniel R.;Tobiska, W. Kent;Mehta, Piyush M.;Licata, R. J.;Drob, Douglas P.;Yoshii, Jean
• 通讯作者: Yoshii, Jean