SAMI3 Simulations of Ionospheric Metallic Layers at Arecibo

Abstract

The Naval Research Laboratory Sami3 is Also a Model of the Ionosphere (SAMI3) ionosphere/plasmasphere code is used to examine the physics of metallic layers at altitudes from 80 to 160 km. Results are presented near the simulated location of the Arecibo observatory (18°N, 66°W). We find that simulations, using winds from the empirical horizontal wind model, produce layers consistent with those observed at Arecibo. Specifically, we find upper semidiurnal and lower diurnal traces similar to those identified in previous observational surveys. While metallic layers are shaped by meridional winds, zonal winds, and electric fields, much of the observed structure is produced if only meridional wind forces are included in the model. Stratification below 110 km, where the ions are very weakly magnetized, is supported mainly by meridional wind shear.

First simulations of day-to-day variability of mid-latitude sporadic E layer structures

“…1a. This numerical result is similar to previous E s layer simulation results (Carter and Forbes 1999;Krall et al 2020;Mathews and Bekeny 1979). In Case A, the fundamental structure of the E s layer is reproduced; the E s layers are created by the semidiurnal tide, descend with its vertical wind shears, and remain around 100 km.…”

“…2c, but the range of altitude is from 85 km to 130 km altitude because the E s layers in Fig. 2c appear below 130 km and the vertical ion velocity above 130 km is mostly controlled by the meridional winds that is same as the previous numerical results (Carter and Forbes 1999;Krall et al 2020). Positive values in Fig.…”

“…This indicates that the strength of the actual downward neutral winds might be stronger than that in the simulations. Previous numerical studies have neglected the influence of vertical neutral winds on E s layers (Carter and Forbes 1999;Krall et al 2020;Mathews and Bekeny 1979), but many E s layers have been observed below 100 km (Ejiri et al 2019a, b;Raizada et al 2011Raizada et al , 2020. Krall et al (2020) have suggested that meridional winds account for the E s layers below 110 km because the SAMI3 simulations in "meridional winds only" case have reproduced observed layers below 110 km and the simulated layers have been associated with wind shears of meridional winds.…”

“…Several simulations have been performed to investigate the tidal effects in E s layers (Carter and Forbes 1999;Krall et al 2020;Mathews and Bekeny 1979). However, the neutral winds used in these simulations did not consider the day-to-day variability of the tides and thus, the E s layers were neither quantitatively nor qualitatively reproduced.…”

Temporal Evolution of Three‐Dimensional Structures of Metal Ion Layer Around Japan Simulated by a Midlatitude Ionospheric Model

“…It is believed that these structures are caused mainly due to additional wind shears produced by the atmospheric gravity waves (e.g., Roddy et al, 2007;Rowe, 1974). Till date, many numerical studies of MILs have been conducted by a variety of global and regional ionospheric models (e.g., Carrasco et al, 2007;Carter & Forbes, 1999;Chu & Yu, 2017;Huba et al, 2019;Krall et al, 2020;Shinagawa et al, 2017). Huba et al (2019) and Krall et al (2020) have performed SAMI3 simulations with Horizontal Wind Model (HWM14) (Drob et al, 2015), and have shown 3-D structures of the MILs for the first time.…”