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

这个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)大约50-200K的增加。这一现象是由临近午夜低纬地区的空气汇聚造成的。目前基于物理的数值模型不能以通常观察到的幅度再现MTM现象。这种无能为力的含义表明，低纬F区等离子体和热层之间的离子中性耦合以及来自下方的潮汐强迫的影响还没有被很好地理解。这个项目将使用从Cedar、Madrigal和本地数据库获得的非相干散射雷达(ISR)获得的离子温度数据来研究MTM特征。具体地说，由于MTM是一个赤道过程，因此重点是利用来自低纬阿雷西博和Jicamara ISR的数据来描述MTM的特征。ISR MTM将在幅度、发生时间和时间持续时间方面进行表征。初步统计表明，有大约400天的阿雷西博和吉卡马卡数据可供研究，其分布方式将允许确定MTM的季节和太阳活动变化。在阿雷基帕使用法布里-珀罗涉仪(FPI)获得了MTM发生的地面气候学，但由于多云条件，这种气候学不包括南半球的夏季月份(11月至3月初)。目前的项目用来自Jicamara的ISR离子温度数据填补了这一空白，并将气候学扩展到阿雷西博的纬度。FPI提供高度集成的光学信息，因此不提供MTM高度依赖关系的信息。另一方面，雷达确实提供了高度的函数结果。对MTM高度依赖关系的系统研究是该项目的主要目标之一。对这种高度相关性的了解对于任何尝试建模都是至关重要的，例如潮汐模式的高度穿透，因此，作为另一个目标，将进行MTM特性的模型比较。另一个目标是将阿雷西博和Jicamara附近现有的雷达数据与光学(FPI和全天成像仪)和数字探空仪数据进行比较。这项工作提供了对MTM的第一个多诊断研究。将利用埃尔莱昂西托(31.8%S)和米尔斯通山ISR(42.6N)的全天成像仪数据来研究赤道MTM现象的纬度范围。该项目涉及的科学问题是：围绕ISRS提供的时间、高度和纬度信息建立的多诊断方法能否提高我们对MTM的了解？

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?