Resolving Long-Standing E-region Data/Model Discrepancies

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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.