Electromagnetic energy deposition rate in the polar upper thermosphere derived from the EISCAT Svalbard radar and CUTLASS Finland radar observations

• Main Authors: Fujiwara, H., Kataoka, R., Suzuki, M., Maeda, S., Nozawa, S., Hosokawa, K., Fukunishi, H., Sato, N., Lester, M.
• Other Authors: Department of Geophysics, Graduate School of Science, RIKEN - Institute of Physical and Chemical Research Japon (RIKEN), Faculty for the Study of Contemporary Society, Solar-Terrestrial Environment Laboratory Nagoya (STEL), Nagoya University, University of Electro-Communications Tokyo (UEC), National Institute of Polar Research Tokyo (NiPR), Department of Physics and Astronomy Leicester, University of Leicester
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; EISCAT; Svalbard
• Online Access: https://hal.science/hal-00318410; https://hal.science/hal-00318410/document; https://hal.science/hal-00318410/file/angeo-25-2393-2007.pdf

International audience From simultaneous observations of the European incoherent scatter Svalbard radar (ESR) and the Cooperative UK Twin Located Auroral Sounding System (CUTLASS) Finland radar on 9 March 1999, we have derived the height distributions of the thermospheric heating rate at the F region height in association with electromagnetic energy inputs into the dayside polar cap/cusp region. The ESR and CUTLASS radar observations provide the ionospheric parameters with fine time-resolutions of a few minutes. Although the geomagnetic activity was rather moderate ( Kp =3 + ~4), the electric field obtained from the ESR data sometimes shows values exceeding 40 mV/m. The estimated passive energy deposition rates are also larger than 150 W/kg in the upper thermosphere over the ESR site during the period of the enhanced electric field. In addition, enhancements of the Pedersen conductivity also contribute to heating the upper thermosphere, while there is only a small contribution for thermospheric heating from the direct particle heating due to soft particle precipitation in the dayside polar cap/cusp region. In the same period, the CUTLASS observations of the ion drift show the signature of poleward moving pulsed ionospheric flows with a recurrence rate of about 10?20 min. The estimated electromagnetic energy deposition rate shows the existence of the strong heat source in the dayside polar cap/cusp region of the upper thermosphere in association with the dayside magnetospheric phenomena of reconnections and flux transfer events.