Resolving Long-Standing E-region Data/Model Discrepancies

该奖项解决了一个长期存在的问题，即在高度接近110公里的上层大气层(电离层E区)的电离部分，模拟的等离子体密度与观测到的等离子体密度之间存在系统性差异。据推测，造成这些差异的一个关键原因是与O、O2和N2与太阳光子的电离反应(光致电离)有关的低分辨率模型参数。当前模型所采用的分辨率不足意味着没有适当地考虑到光电离的窄“窗口”。这项工作将增进对E区三个最重要的物种(O、O2和N_2)的这些电离窗口的理解，以及对E区电离速率和密度的影响。描述电离反应的新参数(电离截面)将使用现代量子力学方法对所有三种物种进行计算。这些参数很重要，因为它们决定了发生电离过程的概率。新的横截面将提供给原子和分子物理界。这对天体物理学和行星科学也很重要，它们将改善不同领域之间的协同作用。此外，该项目将通过向学生群体多样化的伙伴机构之一的学生提供研究项目来扩大学生从事研究的机会。该奖项支持的工作将(1)使用用于光电子碰撞电离和光电子碰撞电离的现代量子力学方法计算所有三个主要物种的新截面，(2)进一步开发大气光电离代码和大气紫外线辐射综合代码(AURIC)，以适当地结合改进的电离率、光电子通量和电子密度，(3)通过与低地球轨道卫星测量的E区光电子通量以及由气象、电离层和气候(COSMIC)卫星和阿雷西博非相干散射雷达星座观测系统测量的E区电子密度进行比较，验证新模型的输出。以及(4)向社会提供开发的模型。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award addresses a long-standing problem of systematic discrepancies between modeled and observed plasma densities in the ionized portion of the upper atmospheric layer near 110 km in altitude (ionospheric E region). It is hypothesized that a key reason for these discrepancies is low-resolution model parameters related to ionization reactions of O, O2, and N2 with solar photons (photoionization). Insufficient resolution employed by the current models means that narrow "windows" of photoionization are not being properly accounted for. This work will improve the understanding of these windows of ionization for the three most important species in the E region (O, O2, and N2) and the effects on E-region ionization rates and densities. New parameters describing ionization reactions (ionization cross sections) will be calculated for all three species using modern quantum-mechanical methods. These parameters are important since they determine the probability that an ionization process will occur. The new cross sections will be provided to the atomic and molecular physics community. This will be also important to astrophysics and planetary sciences, which will improve synergies between different fields. In addition, the project will expand student opportunities to engage in research by offering research projects to students at one of the partner institutions with a diverse student population. The work supported by this award will (1) calculate new cross sections for all three major species using modern quantum-mechanical methods for both photo- and photoelectron-impact ionization, (2) develop further the atmospheric photoionization code and the Atmospheric Ultraviolet Radiance Integrated Code (AURIC) to properly incorporate the improved ionization rates, photoelectron fluxes, and electron densities, (3) validate the new model outputs by comparing with E-region photoelectron fluxes measured by the low-Earth-orbit satellites and E-region electron densities measured by the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites and the Arecibo incoherent scatter radar, and (4) provide the developed models to the community.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.