CEDAR: Comprehensive Use of Incoherent Scatter Radar Data to Study the Equatorial Midnight Plasma and Neutral Temperature Maxima (MTM)

该项目将研究午夜最高温度（MTM），这是夜间赤道热层中性温度（Tn）约50-200 K的增强。这种现象是由低纬度地区午夜附近的空气会聚造成的。目前基于物理学的数值模型无法再现MTM现象与通常观察到的振幅。这种无能的含义表明，低纬度F区等离子体和热层之间的离子中性耦合和来自下面的潮汐力的影响还没有得到很好的理解。该项目将使用来自CEDAR、Madrigal和本地数据库的非相干散射雷达（ISR）获得的离子温度数据来研究MTM功能。具体而言，由于MTM是一个赤道过程，重点放在MTM特性使用低纬度Arecibo和Jicamarca ISR的数据。ISR MTM将在振幅、发生时间和持续时间方面进行表征。初步统计表明，有约400天的阿雷西博和希卡马卡数据可用于研究，其分布方式将允许确定MTM的季节和太阳活动变化。在阿雷基帕用法布里-珀罗干涉仪（FPI）获得了MTM发生的地面气候学，但由于多云条件，该气候学不包括南方夏季（11月至3月初）。目前的项目填补了这一空白与ISR离子温度数据从Jicamarca和扩大气候阿雷西博的纬度。FPI提供高度集成的光学信息，因此不提供关于MTM的高度依赖性的信息。另一方面，雷达提供的结果是高度的函数。系统地研究MTM的高度依赖性是本项目的主要目标之一。这种高度依赖性的知识是至关重要的任何尝试，以模拟，例如，潮汐模式的高度渗透，因此，作为一个额外的目标，MTM特性的模型比较将进行。另一个目的是将雷达数据与在阿雷西博和希卡马卡附近可获得的光学（FPI和全天空成像仪）和数字式探空仪数据进行比较。这项工作提供了MTM的第一个多诊断研究。将使用El Leoncito（31.8 S）的全天成像仪数据和Millstone Hill ISR（42.6 N）数据研究赤道MTM现象的纬度范围。在这个项目中解决的科学问题是：可以围绕由ISR提供的时间，高度和纬度信息建立一个多诊断方法，提高我们的MTM的知识？

This project will investigate the midnight temperature maximum (MTM), an enhancement of the neutral temperature (Tn) of roughly 50-200 K in the nighttime equatorial thermosphere. The phenomenon is created by the convergence of air near midnight at low latitudes. Current physics-based numerical models are not able to reproduce the MTM phenomenon with the amplitudes commonly observed. The implication of this inability indicates that the ion-neutral coupling between the low-latitude F-region plasma and the thermosphere and the influence of tidal forcing from below are not well understood. This project will investigate the MTM feature using ion temperature data obtained with Incoherent Scatter Radars (ISRs) from the CEDAR, Madrigal, and local databases. Specifically, since the MTM is an equatorial process, emphasis is placed on MTM characterization using data from the low-latitude Arecibo and Jicamarca ISRs. The ISR MTM will be characterized in terms of amplitude, time of occurrence, and temporal duration. A preliminary count indicates that there are ~400 days of Arecibo and Jicamarca data available for the study, distributed in a way that will allow the determination of seasonal and solar activity variations of the MTM. A ground-based climatology of MTM occurrence has been obtained with Fabry-Perot interferometers (FPIs) at Arequipa, but this climatology does not include the austral summer months (November to early March) due to cloudy conditions. The current project fills this gap with ISR ion temperature data from Jicamarca and expands the climatology to Arecibo's latitude. FPIs provide height-integrated optical information and so provide no information on the height dependence of the MTM. Radars, on the other hand, do provide results as a function of altitude. A systematic study of the height dependence of the MTM is one of the main goals of this project. Knowledge of this height dependence is crucial to any attempt to model, for example, the height penetration of tidal modes, so, as an additional goal, model comparisons of MTM characteristics will be carried out. An additional objective is the comparison of the radar data with optical (FPI and all-sky imager) and digisonde data available at Arecibo and near Jicamarca. This effort provides the first multi-diagnostic study of the MTM. All-sky imager data at El Leoncito (31.8 S) and Millstone Hill ISR (42.6 N) data will be used to study the latitudinal extent of the equatorial MTM phenomenon. The scientific question addressed in this project is: can a multi-diagnostic approach established around the temporal, altitudinal and latitudinal information provided by ISRs improve our knowledge of the MTM?