Solar Wind Control of Alfven Wave Power in the Polar Region

极地地区阿尔文波发电的太阳风控制

• 批准号: 1613134
• 负责人: Andreas Keiling
• 金额: $ 38.29万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1613134&HistoricalAwards=false
• 关键词: Solar; Wind; Control; Alfven; Wave

This project will quantify the global distribution of Alfven waves in the polar region and its variations with solar wind conditions, geomagnetic storm conditions, and auroral substorm phase. Alfven waves are an essential component of the dynamics and associated energy transport within the Earth's magnetosphere. This has become more and more apparent with each satellite mission into the magnetosphere. Significant Alfven wave activity has been observed by satellites traveling through the plasma sheet, the plasmasphere, the tail lobes, the auroral zone, and the reconnection regions in the magnetotail. Alfven waves are oscillations traveling along magnetic field lines. Much like waves moving outward from a stone tossed into the water, the Alfven waves carry information to other locations along magnetic field lines about changes in the magnetic field or currents at the site of their generation. At these other locations, the waves can be dissipated supplying their energy to power different processes remote from the original energy source. For example, in the polar ionosphere, the dissipation of Alfven waves supplies energy to accelerate the electrons responsible for creating breathtaking auroras. These Alfven waves are thought to originate in strong plasma jets within the stretched magnetotail far from the polar ionosphere. The project will support a graduate student for the summer thus contributing to the training of the next generation scientific workforce. The advances in knowledge of an energy transport process important to the dynamics of the magnetosphere will in the long term improve models of space weather forecasting, of value to a technological society.The project proposed here will develop statistical maps of Alfven wave power observed by the NASA Polar spacecraft and quantify how these maps vary depending on solar wind and interplanetary magnetic field parameters and storm and substorm conditions. Results from MHD modeling will be compared to the statistical maps to validate the MHD simulations. The study will use tools similar to and the methodology of earlier work by the PI, but will include 10 years of data instead of the one-year interval used previously. This will allow the statistical examination of Alfven wave power for a wide-range of different conditions and geomagnetic activity levels. New insights about energy transport and dynamics of the Geospace system are expected.

该项目将量化极地地区阿尔芬波的全球分布及其随太阳风条件、地磁风暴条件和极光次风暴阶段的变化。阿尔芬波是地球磁层内动力学和相关能量传输的重要组成部分。随着每一次进入磁层的卫星任务，这一点变得越来越明显。通过穿越等离子体层、等离子体层、尾叶、极光区和磁尾重联区的卫星观测到了显著的阿尔芬波活动。阿尔芬波是沿磁力线传播的振荡。就像从扔进水里的石头向外移动的波一样，阿尔芬波沿着磁力线将关于磁场或其产生地点的电流变化的信息带到其他位置。在这些其他位置，波可以被消散，为远离原始能源的不同过程提供能量。例如，在极地电离层，阿尔芬波的消散提供了能量，以加速产生令人惊叹的极光的电子。这些阿尔芬波被认为起源于远离极地电离层的伸展磁尾内的强等离子体喷流。该项目将资助一名研究生度过暑假，从而有助于培训下一代科学工作者。从长远来看，关于对磁层动力学很重要的能量传输过程的知识的进展将改进空间天气预报的模型，这对技术社会是有价值的。这里提议的项目将编制美国宇航局极地航天器观测到的阿尔芬波功率的统计地图，并量化这些地图如何随太阳风和行星际磁场参数以及风暴和亚风暴条件而变化。MHD建模的结果将与统计地图进行比较，以验证MHD模拟的有效性。这项研究将使用与PI早期工作类似的工具和方法，但将包括10年的数据，而不是以前使用的一年间隔。这将允许对大范围不同条件和地磁活动水平的阿尔芬波功率进行统计检查。人们期待着对地球航天系统的能源运输和动力学有新的见解。