CEDAR: Modeling Metastable Helium Emissions in the Terrestrial Thermosphere

这项由计算物理公司和西南研究院提出的合作研究将对高层大气1083气辉发射的幅度和空间变化进行模拟研究。该项目将在研究人员之前的探索工作的基础上进行两年的努力。研究人员将在共轭光电子通量的迭代计算中包括光电子通量通过等离子体层时衰减的经验和分析描述。他们还将生成氦分布的综合地图(纬度与当地时间)，以及在各种地球物理条件下产生的1083 nm和388.9 nm的发射强度，这既是为了揭示气辉发射对各种输入的敏感性，也是为了支持分析和解释其他人获得的1083 nm和388.9 nm数据。在第二年，他们将评估用于遥感热层温度和运动的线轮廓特征。氦是高层热层动力学的示踪剂，因此测量的线中心位移可以为高层热层的一般环流模式提供一个独特的检验。然而，由于1083排放峰值高度在400公里以上，观测到的位移将不构成直接的风速测量，而是反映由密度和温度的纬向和经度梯度以及风型决定的横向(弹道)通量的大小。

This collaborative research, proposed by Computational Physics, Inc. and Southwest Research Institute, will carry out modeling studies of the magnitude of and spatial variation in the upper atmosphere's 1083 airglow emission. The project will build upon the investigator's previous exploratory work in a two-year effort. The investigators will include empirical and analytic descriptions of the attenuation of photoelectron fluxes upon passage through the plasmasphere in the iterative calculation for conjugate photoelectron fluxes. They will also generate comprehensive maps (latitude vs. local time) of helium distributions and resulting 1083 nm and 388.9 nm emission intensities under a variety of geophysical conditions, both for revealing the sensitivities of the airglow emissions to various inputs and for supporting the analysis and interpretation of 1083 nm and 388.9 nm data obtained by others. In the second year, they will assess line profile features for remote sensing of thermospheric temperatures and motions. Helium is a tracer of upper thermospheric dynamics, so that measured line center displacements may offer a unique test of general circulation models of the upper thermosphere. However, since the 1083 emission peak altitude is above 400 km, observed displacements will not constitute a direct wind speed measurement, but rather will reflect the magnitude of lateral (ballistic) fluxes governed by latitudinal and longitudinal gradients in density and temperature as well as by wind patterns.