Q2DW-Tide and -Ionosphere Interactions as Observed From ICON and Ground-Based Radars

Area of Science:

• Space Physics
• Atmospheric Science
• Aeronomy

Background:

• Quasi-2-day wave (Q2DW) is a significant atmospheric wave phenomenon.
• Nonlinear interactions between atmospheric waves can generate new wave modes.
• Understanding these interactions is crucial for modeling the upper atmosphere and ionosphere.

Purpose of the Study:

• Investigate the propagation of a Q2DW event from 96 to 250 km.
• Analyze nonlinear interactions between Q2DW and migrating tides to form secondary waves (SWs).
• Determine the impact of Q2DW and SWs on topside F-region plasma drifts and ion densities.

Main Methods:

• Analysis of coincident Ionospheric Connections Explorer (ICON) data (neutral winds, plasma drifts, ion densities).
• Utilized wind measurements from four low-latitude specular meteor radars (SMRs).
• Employed longitude-UT fits and fits to space-based zonal wavenumbers to infer Q2DW and SW characteristics, alongside published numerical simulations.

Main Results:

• Identified Q2DW westward-propagating components with zonal wavenumbers s=2 and s=3 (Q2DW+2, Q2DW+3).
• Observed secondary waves (SWs) in ICON measurements, inferred from Q2DW+2 and Q2DW+3 characteristics.
• Quantified total Q2DW ionospheric responses: F-region drifts of ±25 ms⁻¹ (field-aligned) and ±5-7 ms⁻¹ (meridional), and ion density perturbations of ±10%-25%.

Conclusions:

• Secondary waves (SWs) can significantly contribute to Q2DW-driven winds, drifts, and plasma densities.
• Nonlinear interactions play a key role in shaping the dynamics of the upper atmosphere.
• This study highlights the complex interplay between different atmospheric wave phenomena in the ionosphere.