The dynamic effects of the magnetosphere on electric fields in the low- and mid-latitude ionosphere constitute a crucial area of magnetosphere-ionosphere coupling that has received relatively little attention from researchers. During magnetic storms, electric fields generated in the magnetosphere penetrate promptly to low latitudes. These electric fields then play a major role in storm-associated disruptions of the ionosphere, including large-scale changes in ionospheric structures and equatorial Spread F. An understanding of longitudinal and seasonal effects is central to developing the ability to forecast these conditions, which have major space weather effects. Developed as a magnetospheric model, the Rice Convection Model (RCM) assumes that the magnetic field in the ionosphere is a dipole that is aligned with the rotation axis, so it cannot presently be used to treat longitudinal or seasonal effects. On the other hand, the Prairie View Dynamo Code (PVDC), which is used to model the ionosphere, uses Euler potentials and treats ionospheric currents using the full International Geomagnetic Reference Field (IGRF) magnetic field model. Although the PVDC does not treat the magnetosphere, it is presently capable of treating wind-driven electric fields and currents, including seasonal and longitudinal effects. The central task of this project is to produce a new version of the RCM and a corresponding new version of the PVDC, that are both based on the same Euler-potential formalism. The new version of the RCM will be compatible with the IGRF or other realistic models of the Earth's magnetic field. Use of the same formalism in both codes will facilitate collaboration and data exchange. Once the new RCM is developed and tested, it will be applied to the study of prompt-penetration electric fields in large storms, with particular emphasis on longitudinal and seasonal effects. The new RCM computational machinery will be available for incorporation into the large space weather codes that include coupled full-physics models of the thermosphere, ionosphere, and magnetosphere. The improved PVDC will investigate the longitudinal variation of the quiet-time electric field. Prairie View A&M University is an HBCU with 95% black students enrolment. Carrying out this proposal would strengthen the University's research ability, and encourage more black students, who are underrepresented in the field of space science, to participate in the proposed project.