Collaborative Research: CEDAR: Measuring Photoelectron Distributions and Fluxes in the Ionosphere

This project will exploit high resolution plasma line observations made by the Arecibo Radar to significantly increase the number of photoelectron observations available to the community. The Earth’s ionosphere is created by the Sun’s radiation, which breaks up particles in the upper atmosphere to create plasma. One product of this ionization process is a high energy electron called a photoelectron. Photoelectrons are constantly created during the day and are important for sustaining and heating the ionosphere. Measurements of photoelectrons are rare and difficult to make. Archived experiments from the Arecibo Observatory are one of few datasets that can be used to create meaningful photoelectron measurements. This work will further our understanding of the interaction between photoelectrons and plasma in the ionosphere. The primary output of this research is altitude resolved measurements of the photoelectron distribution which will be made available to the community. The team is diverse in gender and career stages, including early career researchers. This project will support a graduate student and undergraduate students at an MSI (NJIT). Furthermore, reports and presentations of this research will broaden the community and public’s understanding of Arecibo’s legacy as a unique, world-class instrument. Measurements of photoelectrons in the ionosphere are rare and difficult to make, particularly in situ. This project will significantly increase the number of photoelectron observations available to the community by exploiting high resolution plasma line observations made by the Arecibo radar. The team will use a combination of experiment, kinetic plasma theory, and data science to answer the following questions: 1. Does a given photoelectron distribution provide a unique set of plasma line observations? 2. Do asymmetries in the photoelectron distribution create asymmetries in the upshifted versus downshifted plasma lines? and 3. What is the effect of photoelectrons on the frequency of the plasma line? The work will improve our understanding of the photoionization process, and the pathway photoelectrons take to heat the ionosphere and resolve the anisotropy of the photoelectron distribution and assess the relative importance of local production and vertical transport of high energy electrons. This work will also create a catalogue and archive of past plasma line experiments at Arecibo, making this unique dataset more accessible to the community through the Madrigal database. The Geospace Facilities (GF) Program cofunds this project. 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.