Semianalytical Estimation of Energy Deposition in the Ionosphere by Monochromatic Alfvén Waves

• Published in: Journal of geophysical research. Space physics 2018-06, Vol.123 (6), p.5210-5222
• Main Authors: Verkhoglyadova, Olga P., Meng, Xing, Mannucci, Anthony J., McGranaghan, Ryan M.
• Format: Article
• Language: English
• Subjects: Alfven waves; Altitude; Altitude effects; Auroral arcs; Computer simulation; Daytime; Dependence; Deposition; E region; Empirical analysis; Empirical models; Energy budget; energy transport; F region; Geomagnetic activity; geomagnetic storm; Geomagnetic storms; Geomagnetism; heating; Ionosphere; Ionospheric dynamics; Ionospheric models; Ionospheric propagation; Joule heating; Latitude; Magnetic fields; Magnetic storms; Magnetohydrodynamics; Ohmic dissipation; Outflow; Storms; Thermosphere; ULF waves; Wave energy; Wave power; Wave propagation
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2017JA025097

For the first time we derive an analytical expression for energy deposition by propagating monochromatic Alfvén waves in the collisional ionosphere‐thermosphere (IT). Based on empirical models of IT parameters, we show an approximately 10% increase in efficiency of energy deposition at high latitudes and about 150 km altitude by Alfvén waves at 5 Hz as compared to static fields of the same magnitude. We analyze the dependence of the wave energy deposition on geomagnetic activity through a Global Ionosphere‐Thermosphere Model (GITM) simulation of IT conditions during the 13–14 October 2016 geomagnetic storm. The peak Alfvén wave contribution occurs in the E layer and lower part of the F layer. Wave‐induced heating is shown to increase in the daytime and postdusk high‐latitude F layer during the storm due to increased wave‐modified conductivity. We estimate that the Alfvén wave contribution to the IT energy budget can reach about 30% of the value of static Joule heating during a strong storm and that the actual percentage increase is dependent on latitude and altitude. This effect carries important implications for ionospheric dynamics, especially for density enhancement in the daytime cusp, heating in the vicinity of auroral arcs and ion outflow. Key Points An analytical expression for energy deposition by propagating Alfvén waves in the collisional ionosphere‐thermosphere is derived The relative efficiency of energy deposition rate of Alfvén wave (up to 5 Hz in frequency) to static field is estimated to be ∼10% at high latitudes and below 250 km altitude We show that Alfvén wave energy deposition can reach about 30% of the value of static Joule heating during a strong storm