Validation of the Parameterized Real-Time Ionospheric Specification Model (PRISM)Version 1.7B

摘要

The most current version of the Parameterized Real-time Ionospheric SpecificationModel (PRISM), version 1.7b, was validated using Digital Ionospheric Sounding System (DISS) measurements of F2 layer critical frequency (foF2) and F2 peak electron density height (hmF2) as the ground truth. PRISM was executed, first, with no real-time input parameter and, second, with Global Positioning System (GPS) Total Electron Content (TEC) measurements as the sole real-time parameter. Hourly values of hmF2 and foF2 over 123 days in 1994-1996 (solar minimum conditions) and covering three seasons (equinox, summer solstice, and winter solstice) were compared for Wallops Island, Virginia, and Point Arguello, California, which both have a GPS receiver and a nearby DISS station. Values of hmF2 and foF2 from the DISS data, the PRISM output with no real-time input parameters, and the PRISM output with the GPS TEC measurements are compared as a function of season and local time. Results indicate PRISM overestimates foF2 by 20-30% when ingesting GPS TEC. On a subsequent execution of PRISM, the GPS TEC measurements were decreased by four TEC units as an estimation of the topside light ion (He, H) and plasmaspheric electrons which are not considered in the physical models of PRISM. PRISM underestimates foF2 by 30-40% and underestimates hmF2 by as much as 40 km in the post-midnight timeframe when driven by the corrected TEC values.