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    Comparison of MLT momentum fluxes over the Andes at four different latitudinal sectors using multistatic radar configurations
    (John Wiley and Sons Inc, 2022-02-27)
    The middle atmosphere over South America, particularly above the Andes mountain range, is known as one of the most dynamically active regions in the world. Previous studies have investigated wave dynamics at mesosphere and lower thermosphere (MLT) altitudes within this region, but only a handful of them have made use of continuous measurements provided by specular meteor radars (SMRs). Furthermore, it was only until recently that MLT horizontal wind gradients were estimated for the first time using Spread Spectrum Interferometric Multistatic meteor radar Observing Network (SIMONe) Argentina, a multistatic SMR network located in southern Patagonia. By observing larger amounts of meteors from different viewing angles, multistatic SMRs allow, among others, for more reliable momentum flux estimates. In this work, we explore and compare the summer and winter MLT momentum flux dynamics at low and middle latitude sectors over the Andes mountain range. We also investigate the intermittency of the total momentum flux over these sectors. For this purpose, we analyze measurements provided by four multistatic SMR networks: SIMONe Peru (12°S), Chilean observation network de Meteor radars (30°S), SIMONe Argentina (49°S) and multi-frequency Agile radar for investigations of the atmosphere-southern Argentina agile meteor radar (54°S). We find that the momentum flux dynamics can change considerably over distances of only a few hundred km (e.g., southern Argentina). On the other hand, the contributions of large momentum fluxes to the total flux can be similar between regions separated by thousands of km (e.g., between Peru and southern Argentina).
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    Climatology of Mesosphere and Lower Thermosphere Diurnal Tides over Jicamarca (12° S, 77° W): Observations and Simulations
    (Springer Science and Business Media Deutschland GmbH, 2023-12-01)
    This work shows a 3-year climatology of the horizontal components of the solar diurnal tide, obtained from wind measurements made by a multistatic specular meteor radar (SIMONe) located in Jicamarca, Peru (12 ∘ S, 77 ∘ W). Our observations show that the meridional component is more intense than the zonal component, and that it exhibits its maxima shifted with respect to the equinox times (i.e., the largest peak occurs in August–September, and the second one in April–May). The zonal component only shows a clear maximum in August–September. This observational climatology is compared to a climatology obtained with the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X). Average comparisons indicate that the model amplitudes are 50% smaller than the observed ones. The WACCM-X results are also used in combination with observed altitude profiles of the tidal phases to understand the relative contributions of migrating and non-migrating components. Based on this, we infer that the migrating diurnal tide (DW1) dominates in general, but that from June until September (November until July) the DE3 (DW2) may have a significant contribution to the zonal (meridional) component. Finally, applying wavelet analysis to the complex amplitude of the total diurnal tide, modulating periods between 5 and 80 days are observed in the SIMONe measurements and the WACCM-X model. These modulations might be associated to planetary waves and intraseasonal oscillations in the lower tropical atmosphere. Graphical Abstract: [Figure not available: see fulltext.].
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    First Coincident Radar and Optical Observations of a Meteor Radio Afterglow
    (Wiley, 2026-03-01)
    It has been hypothesized that Meteor Radio Afterglows (MRAs) occur due to resonant transition radiation (RTR) where suprathermal electrons emit as they pass through electron density inhomogeneities in a turbulent plasma. Meteor trails are thought to produce suprathermal electrons through anion oxidation, which can be identified through meteor persistent trains. Meteor plasma turbulence can be identified through a non‐specular echo from a meteor radar. We present the first radar observations of a MRA that was also observed to produce a non‐specular echo and a persistent train, which indicate the presence of both plasma turbulence and anion oxidation. The observations were made using the Long Wavelength Array station at Sevilleta (LWA‐SV) and the Spread spectrum Interferometric Multi‐static Meteor radar Observing Network in New Mexico (SIMONe‐NM), the Widefield Persistent Train Camera version 2 (WiPT2) and the Global Meteor Network (GMN). Analysis reveals that while the MRA was spatially coincident a range‐spread, non‐specular echo, the brightest MRA emission came from a portion of the trail 8 km higher than the brightest radar scatter. We find that changes in the mean free path and collision frequency may be responsible for the higher altitude emission despite weaker plasma turbulence there. We also present evidence from the SIMONe‐NM head echo that the MRA and non‐specular echo were coincident with fragmentation of the meteoroid, which may have some role to play in both phenomena.
    Scopus© Citations 1  1