Spatial structure of summertime ionospheric plasma near magnetic noon

• Main Authors: Sims, R. W., Pryse, S. E., Denig, W. F.
• Other Authors: Institute of Mathematical and Physical Sciences, AFRL Space Vehicles Directorate, Air Force Research Laboratory (AFRL), United States Air Force (USAF)-United States Air Force (USAF)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2005
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Svalbard; EISCAT
• Online Access: https://hal.science/hal-00317479; https://hal.science/hal-00317479/document; https://hal.science/hal-00317479/file/angeo-23-25-2005.pdf

International audience Results are presented from a multi-instrument study of the spatial distribution of the summertime, polar ionospheric electron density under conditions of relatively stable IMF B z <0. The EISCAT Svalbard radar revealed a region of enhanced densities near magnetic noon that, when comparing radar scans from different local times, appeared to be spatially confined in longitude. This was identified as the tongue-of-ionisation (TOI) that comprised photoionisation of sub-auroral origin that is drawn poleward into the polar cap by the anti-sunward flow of the high-latitude convection. The TOI was bounded in longitude by high-latitude troughs; the pre-noon trough on the morning side with a minimum near 78° N and the post-noon trough on the afternoon side with a minimum at 80° N. Complementary measurements by radio tomography, the SuperDARN radars, and a DMSP satellite, together with comparisons with earlier modelling work, provided supporting evidence for the interpretation of the density structuring, and highlighted the role of plasma convection in the formation of summertime plasma distribution. Soft particle precipitation played only a secondary role in the modulation of the large summertime densities entering the polar cap.