Analysis and Applications of Ionospheric Measurements from the Integrated Miniaturized Electrostatic Analyzer

Abstract

Since the beginning of the space age electrostatic instruments have aided us in understanding the near Earth space environment. Measurements of the ionosphere are valuable in understanding geomagnetic phenomena and can be used to improve space weather forecasting in order to reduce the societal impact of extreme space weather. The Integrated Miniaturized Electrostatic Analyzer (iMESA) was a satellite based parallel plate electrostatic analyzer that characterized the ion density and ion temperature in the vicinity of the spacecraft and quantified the electric potential of the spacecraft with respect to the background plasma. The instrument directly measured the ion current through the sensor head as a result of the motion of the spacecraft through the relatively stationary plasma. The current was amplified, measured, digitized, and stored by the instrument electronics before transmission to the ground. The transmitted data were post processed and analyzed to provide the quantities describing the environment near the spacecraft. The ultimate goal of this research is to demonstrate that the ion density measurements provided by iMESA can improve the accuracy of a space weather model and can, by extension, aid in space weather forecasting. The initial milestones of the project were the development of procedures to calibrate the instrument using simulations and process the raw instrument data. The calibrated and processed data had to be validated against another ionospheric instrument to ensure the quality of the iMESA data products. The International Reference Ionosphere (IRI) was used to convert ionosonde measurements to electron density and temperature at the location of the spacecraft from which a modeled anode current was calculated using the the instrument response function derived from the calibration simulations. The modeled anode current agrees with the current measured by iMESA to within a Pearson's coefficient of 0.848. A direct comparison of the plasma densities and ion temperatures from IRI and iMESA produced a determined Pearson's coefficient r = 0.549. While a direction comparison of measured iMESA ion temperature and modeled ion temperature from IRI produced a Pearson's coefficient of r = 0.061. The validated ion density measurements were assimilated into the Global Positioning System Ionospheric Inversion (GPSII) model ionospheric program and predicted ionograms were generated. The inclusion of iMESA data into the GPSII improved the linearity of the modeled data when compared to ionosonde measurements but failed to improve the skill score of the model for the height and frequency of the F2 peak.