Direct Kelvin‐Helmholtz Instability Detection at the Ionospheric E Region Electron Density

Abstract

New high‐resolution measurements by Sanya incoherent scatter radar (ISR) employing a wide‐bandwidth chirp signal now enable spatiotemporal resolutions of 37.5 m and 50 s. We have applied these new capabilities for observations of Kelvin‐Helmholtz instability (KHI) dynamics in the low‐latitude ionosphere E region. The KHI evolution exhibited ∼±150 m oscillations in altitude, billows “periods” of ∼3–8 min due to horizontal advection, and 1–3 km vertical extents in the sporadic E layers, consistent with the classic understanding of KHI at these altitudes. Our results confirm the quasi‐period character of KHI and first reveal the KHI modulates the plasma layers by horizontal advection in direct observation. They also demonstrate the benefits of improved spatiotemporal resolutions for more general studies of the low‐latitude E region ionosphere.