The Role of the Fountain Effect in the Evolution of Ionospheric Structures in Low and Mid Latitudes

地球电离层是大气中电荷粒子(离子和自由电子)浓度相对较高的一层，从地球表面上方约50至600英里(80至1000公里)延伸。带电粒子的密度随位置和时间的变化而变化，并受到地球磁场变化的影响。这些密度波动被称为影响无线电通信和GPS精度的不规则现象。一种特殊的现象是带电粒子(等离子体)的局部耗尽，称为等离子体气泡。该项目将重点研究中低纬度电离层中磁平静期的白天电子密度不规则性和中纬度等离子体气泡在磁扰动期的不规则性。这两种现象都被认为与赤道等离子体气泡密切相关。假设这两种现象都与喷泉效应引起的赤道气泡输运密切相关。该项目的成功将建立一天中赤道气泡的完整演化情景，并结束关于中纬度气泡来源的争议。项目组将通过分析卫星观测(ROCSAT-1、C/NOFS、CHAMP、SWARM和DMSP)来确定白天不规则和中纬度气泡的特征。这些现象背后的物理过程将通过进行SAMI3模型模拟来确定。白天的不规则性和中纬度气泡都是未开发的领域，因为对它们的特征和来源没有明确的了解。气泡一直被理解为赤道地区的现象，但异常大的气泡可能会发展并到达中纬度。该项目首次尝试通过模型模拟来验证这一解释。拟议的工作是可行的，因为该项目将利用现有的观测数据和经过验证的电离层模型进行。项目组由观测数据、模型和电离层现象方面的专家组成，因此可以有效地执行该项目。约翰·霍普金斯大学应用物理实验室(APL)的地球空间与地球科学小组一直在接待高中和大学的实习生，以便他们能够参与工作人员的项目。一名大学生将在夏季被邀请参与这项工作，该团队将提供数据分析、计算机编程和电离层等离子体物理方面的指导。该项目将提供一个机会，通过与韩国空间科学研究所的李伍英博士合作，促进空间飞行任务和地面观测方面的合作。该项目还将推动对中等生日间违规行为的其他调查。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 the layer of the atmosphere that has a relatively high concentration of charged particles (ions and free electrons) that extends from about 50 to 600 miles (80 to 1,000 km) above the Earth's surface. The density of the charged particles varies with location and time and is influenced by the change of Earth’s magnetic field. These density fluctuations are called irregularities that affect radio communications and GPS accuracy. One special phenomenon is a regional depletion of charged particles (plasma), which is referred to as plasma bubbles. This project is to perform a focused study of the daytime electron density irregularities during magnetically quiet periods and midlatitude plasma bubbles during magnetically disturbed periods in the low and mid latitude ionosphere. Both phenomena are believed to be closely related to equatorial plasma bubbles. The hypothesis is that both phenomena are closely related to the transport of equatorial bubbles by the fountain effect. The success of this project will establish the full evolution scenario of equatorial bubbles throughout a day and provide closure to the dispute regarding the sources of midlatitude bubbles. The project team will establish the characteristics of daytime irregularities and midlatitude bubbles by analyzing satellite observations (ROCSAT-1, C/NOFS, CHAMP, SWARM, and DMSP). The physical processes underlying these phenomena will be identified by conducting SAMI3 model simulations. Both daytime irregularities and midlatitude bubbles are unexplored fields in that there is no clear knowledge of their characteristics and origin. Bubbles have been understood as the phenomena in the equatorial region, but anomalously large bubbles can develop and reach midlatitudes. This project is the first attempt to validate this interpretation by model simulations. The proposed work is feasible because the project will be performed using existing observational data and a proven ionospheric model. The project team consists of experts in observational data, models, and ionospheric phenomena, and therefore, can effectively perform the project. The Geospace & Earth Science group at Applied Physics Laboratory (APL) in Johns Hopkins University has been hosting high school and college interns so that they can participate in the staff’s projects. One college student will be invited in the summer to participate in this work and the team will provide mentoring on data analysis, computer programming, and ionospheric plasma physics. This project will provide an opportunity to facilitate collaboration between APL and Korea Space science Institute (KASI) in space missions as well as ground-based observations through the collaboration with Dr. Wookyoung Lee at KASI. The project will also motivate other investigations of daytime irregularities in midlaittudes.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.