Studies of the Low-Latitude Ionosphere and Electrodynamics Using Data from the LISN Distributed Observatory

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This project undertakes investigations of outstanding science questions on the low latitude ionosphere, particularly its electrodynamic phenomena, while providing significant modeling and analysis support for the Low Latitude Ionosphere Sensor Network (LISN). LISN is a distributed ionospheric observatory funded by NSF's Major Research Instrumentation program that monitors conditions over the western half of South America. The research plan consists of a three part effort that will: (1) combine the multi-instrument multi-point observations of LISN with physics-based models of the ionosphere and electrodynamics to produce an optimal representation of the ionosphere, the electrodynamics, and its drivers above the western half of equatorial South America; (2) utilize JRO incoherent scatter radar data in the calibration and verification of the LISN generated specifications and eventually integrate JRO into the LISN system; calibration and verification efforts will also make use of airglow Fabry-Perot interferometers available in the region; (3) use the resulting low-latitude representation to address the following science questions: What is (are) the source(s) that determine the magnitude of the pre-Reversal enhancement of the vertical plasma drift and the shear in the east-west drift in the post-sunset F region? How strong is the longitudinal variation of the (generally) sun-synchronous ionosphere? What controls the longitudinal trends in the electrodynamics/ionosphere? What are the relative roles of the three key post-sunset F region quantities on equatorial spread-F occurrence? These quantities are (a) the post-sunset shear in the zonal plasma drift, (b) the pre-reversal enhancement of the vertical plasma drift, (c) the vertical density gradients below the F-region peak. What are the key states of the ionosphere drivers and what conditions lead to the high variability of the low-latitude F region ionosphere and the occurrence of ESF? If one can identify a key variability then how early can ESF occurrence be forecast if that quantity is measured? There are several broader impacts of the research. These include its contribution to efforts to develop predictive capabilities for the low latitude ionosphere which has important applications for communications and navigation and may aid efforts to mitigate the effects of equatorial spread F and reduce the uncertainties in the global-positioning system. The JRO observations and model results will be incorporated into the LISN database which is used by scientists from 10 different countries. A graduate student at the PI institution will participate in the research.