The project aims to improve space weather prediction capabilities by developing an accurate model of electrojet conductivity under disturbed conditions. During periods of intense geomagnetic activity, large currents along the magnetic field lines can induce the formation of strong electrojets, plasma instabilities, and turbulence. This turbulence gives rise to intense anomalous electron heating and nonlinear transport which significantly affects the E-region conductivity. Existing ionospheric models do not include these effects. This limits their ability to accurately model magnetic storms and substorms essential for space weather predictions. Accordingly, the objective of this project is to develop an ionospheric-conductance module which will predict nonlinear currents and anomalous electron heating during magnetic storms and substorms. This module will consist of a look-up table and/or analytic expressions which will return the E-region conductivity matrix for a range of altitudes, latitudes, driving electric fields, and plasma and neutral atmospheric conditions. The project will undertake three tasks: (1) quantitative modeling of anomalous electron heating and nonlinear currents; (2) creation of a conductivity database which accounts for turbulent effects; and (3) testing the modified conductivities in existing magnetosphere and ionosphere simulation codes and models. Supercomputer simulations of 3D E-region turbulence combined with modern theoretical analyses will be applied to determine the heating and conductivities. The predictions of electron heating will be validated using incoherent scatter radar and rocket data, while the predicted ionospheric fields and currents will be tested against magnetometer and SuperDarn data. In order to make the results useful and available, they will be incorporated into the Lyon-Fedder-Mobary (LFM) magnetosphere simulation code and the magnetosphere-ionosphere-thermosphere model (CMIT), two codes that are widely used by the magnetosphere/ionosphere community. The results of the upgraded LFM and CMIT will be tested against the unmodified codes and observations. Particular science questions to be addressed are: What is the nonlinear response of the high-latitude ionosphere to strong convection electric fields? Why is the observed storm-time cross-polar-cap potential often smaller than that predicted by existing models? Do the turbulence generated changes in conductivities mostly or fully account for the reason that models fail to account for observations?
Magnetic storms and substorms are major manifestations of space weather. They result from a complex interaction of the solar wind with the Earth's magnetosphere, ionosphere, and neutral atmosphere. Magnetic storms have technological impacts: they may cause the malfunction or permanent damage of satellites (including GPS), destroy communication cables, disrupt high-voltage power grids and pipelines, and have deleterious effects on telecommunications, navigation, surveillance and other activities. There is also a potential hazard to astronauts and high-altitude/high-latitude aircraft passengers. Hence timely and accurate predictions of magnetic storms and substorms, along with their major quantitative characteristics, become an important and urgent task. During periods of intense geomagnetic activity, electric fields from the magnetosphere penetrate down to the high-latitude E-region ionosphere where they form strong electrojets, excite plasma instabilities and create turbulence. Electrojet conductivities play an important role in the magnetosphere-ionosphere system. They determine the evolution of field-aligned currents, the polar-cap potential saturation level, and eventually affect the entire structure of the near-Earth plasma. In order to accurately forecast or now-cast space weather during storm and substorm conditions, quantitative modeling of the electrojet response is essential. E-region turbulence gives rise to intense anomalous electron heating and nonlinear transport, both of which affect significantly the E-region conductivity. Current ionospheric models do not include these effects. This limits their ability to accurately model magnetic storms and substorms essential for space weather predictions. The major objective of the reported project is to overcome this deficiency. Intellectual Merit of the Project: The reported project has resulted in significantly improved quantitative understanding of how E-region turbulence and other factors (meteor plasma trails and sporadic-E clouds) affect the ionosphere-magnetosphere coupling through anomalous conductivities. It has been achieved through theoretical analysis combined with supercomputer simulations of E-region turbulence. The major results include the calculation of the explicit correction coefficients for the ionospheric conductivities and of the sources for anomalous ionospheric heating. These theoretical results should be used in global models of magnetosphere-ionosphere-thermosphere coupling. Broader Impacts of the Project: The project results will improve space weather forecasting capabilities for strongly disturbed geophysical conditions. In particular, these models will improve the ability to estimate the surges induced in high-latitude power systems and other high-latitude phenomena. This research project has further developed a massively parallel plasma simulation code with a broad range of applications. It has also supported the education and training of students, as well as international (US-Russia) collaboration.
