Auroral Radio Emissions: A Window Into Electron Acceleration Processes

北极光或极光是高能粒子与大气相互作用的结果？在夜空中产生五彩景象的。靠近北极的北极地区是观赏极光的最佳地点。该项目是美国国家科学基金会资助的一个项目的后续，该项目在阿拉斯加的图里克湖部署并校准了一个接收器阵列。该仪器将用于观测极光，并对极光的形成过程有新的发现。研究生和本科生将接受培训，科学数据集将与公众共享。高纬度电磁能量和粒子流的一个重要表现是地球极光，它涉及许多影响电子和离子的加速过程。这些过程既发生在磁层，也发生在电离层，是磁层-电离层耦合的关键组成部分。加速极光电子束的射电辐射，其复杂的时间和空间变化，为加速电子分布和产生它们的过程提供了一个窗口。在这方面，极光中频爆发（MFB）的发射尤其有希望，因为它们与亚暴膨胀弧有关，并且在一定的时间尺度上与阿尔芬加速的超热电子爆发和其他现象（如闪烁的极光）重叠。然而，人们对MFB的了解相对较少：它的来源高度尚不清楚，尽管已经提出了一种机制，表明它与阿尔夫金星极光有关，但它还没有得到观测的最终证实。提出的实验将回答这些和其他关于MFB和极光射电发射的悬而未决的问题，是使用MFB及其时间和频率结构作为极光加速和非线性波过程诊断的关键步骤，以回答电离层背景下这些过程的时空动力学以及它们与风暴和亚风暴等更大动力学过程的关系的关键问题。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 Northern Lights or aurorae result when energetic particles interact with the atmosphere ? producing a colorful sight in the night sky. The Arctic region near the North Pole is a prime location for viewing aurorae. This project is a follow-on to an NSF funded program that deployed and calibrated a receiver array in Toolik Lake, Alaska. This instrumentation will be used to view the aurorae and make new discoveries about how they are created. Graduate and undergraduate students will be trained and the scientific datasets will be shared with the public.A significant manifestation of high-latitude electromagnetic energy and particle flows is the terrestrial aurora which involves many acceleration processes affecting electrons and ions. These processes occur in both the magnetosphere and the ionosphere and are a key component of magnetosphere-ionosphere (M-I) coupling. Radio emissions from the accelerated auroral electron beams, with their complicated temporal and spatial variations, provide a window into the accelerated electron distributions and the processes that produce them. Auroral Medium Frequency Burst (MFB) emissions are especially promising in this regard because they are associated with substorm expansion arcs and exhibit structure on a range of time scales overlapping with those of Alfvenically accelerated suprathermal electron bursts and other phenomena such as flickering aurora. MFB is, however, relatively poorly understood: its source altitudes is not known, and although a mechanism has been proposed that suggests a connection to Alfvenic aurora, it has not been conclusively confirmed by observations. The proposed experiments, which will answer these and other outstanding questions about MFB and auroral radio emissions, are critical steps toward using MFB and its time and frequency structure as a diagnostic of auroral acceleration and nonlinear wave processes, to answer key questions about the temporal and spatial dynamics of these processes in the ionospheric context as well as their relation to larger dynamical processes such as storms and substorms.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.