This manuscript presents a novel and interesting hypothesis about the seeding of equatorial spread F irregularities by meteors. Based on radar experiments, the study postulates that the triggering of these irregularities occurs even under very stable ionospheric conditions. The article demonstrates significant work on the relationship between meteors and F region irregularities at equatorial latitudes. The novel mechanism can encourage the ionospheric community to test this hypothesis.

The three-dimensional variational technique (3DVar) is a popular technique used for data assimilation. Background error covariance (BEC) influences the performance of 3DVar technique. In this study, two formulations of BEC, namely the cv5 and cv6 options in the 3DVar assimilation in the Weather Research and Forecasting (WRF) model, are compared. It is found that the formulation of BEC impacts the analysis. Utilising the cv6 option moderately improves the simulation of monsoon depressions.

We studied the characteristics of gravity waves in the lower stratosphere using high-vertical-resolution COSMIC GPS-RO temperature profiles retrieved by the FSI method. We analyzed vertical wavenumber spectrum of the normalized temperature perturbations and calculated the wave potential energy in the wavelength ranges from 0.5 to 3.5 and 0.5 to 1.75 km. We investigated the correlation between the spectral parameters with topography and the background mean zonal winds.

The nearshore wave characteristics are presented during the active sea/land breeze period based on data measured at 5 m and 15 m water depth in the eastern Arabian Sea. Prior to the sea breeze, the wave field is dominated by swell and during the sea breeze, wind-sea dominates with superimposed swell. Reduction in the wave height of wind-sea is around 20 % and that of the swell is around 10 % from 15 m to 5 m water depth.

Convection reversal boundary (CRB) is a special characteristic of plasma flow patterns in the high-latitude ionosphere. It is typically a border line between regions with closed and open Earth’s magnetic field lines. This paper investigates seasonal and solar cycle trends in the CRB location. We use an extensive Super Dual Auroral Radar Network data base for 19 years of operation and apply a non-standard approach of making monthly averaged convection maps.

Many independent observations have shown that long-period electromagnetic waves (with periods of several minutes) are preferably observed inside the auroral oval. Here we examine theoretically the possibility of Alfven wave generation by fluctuating large-scale field-aligned currents which couple outer space and the auroral ionosphere. The elaborated model indeed confirms the feasibility of an additional mechanism of long-period wave excitation which can operate at auroral latitudes.

With observations of the Cluster spacecraft, we report in situ evidence of energetic ions scattered into the loss cone during the inbound pass from the plasma sheet into the plasmasphere. Our results suggest that energetic ions scattering into the loss cone in the central plasma sheet and the outer boundary of the plasmaspheric plume are attributed to the field line curvature scattering mechanism and EMIC wave scattering mechanism, respectively.

The differential code bias (DCB) is one of main errors for high-precision GNSS TEC estimation and positioning applications. In this paper, daily DCBs of the BeiDou System (BDS) are estimated and investigated from multi-GNSS network observations (2013–2014), which are compared with GPS results. The DCB of BDS satellites is a little less stable than GPS results, especially for GEO satellites. Zero-mean condition effects are not the dominant factor for the higher RMS of BDS satellite DCB.

A significant anomaly was observed in the ionogram at Kazan, Russia, following the 2010 M8.8 Chile earthquake, which was caused by vertical ground motions of Rayleigh waves and the resulting acoustic waves propagating upward. The anomaly was characterized by steep satellite traces for which the range increased rapidly with frequency. The inclined ionospheric density perturbation caused oblique returns of sounding radio waves in addition to the nearly vertical returns of the main trace.

Analysis of 10 years (2000–2009) of Carbon Tracker (CT-2010) model CO₂ fluxes gives insights into the regional variation of CO₂ fluxes over the Indian land mass. CO₂ emission hot spots overlap with locations of densely clustered thermal power plants, coal mines, and other industrial and urban centres. CO₂ sink regions coincide with locations of dense forests with less industrial centres. CO₂ fossil fuel emissions show good agreement with two bottom-up inventories REAS v1.11 and EDGAR v4.2.

Periodic waves have been observed over São João do Cariri during almost one solar cycle. Similarities between the characteristics of these events with observations at other places around the world were noted, primarily the spectral parameters. Most observed waves have appeared during magnetically quiet nights, and the occurrence of those waves followed the solar activity. Due to their characteristics, most of them must have had different generation mechanisms from the Perkins instability.

Coronal Mass Ejections (CMEs) are giant clouds of plasma and magnetic field that erupt from the Sun and travel though the solar wind. They can cause interplanetary shocks in the vicinity of Earth. We show in our paper that the region that follows CME-driven shocks, known as sheath region, can obtain a planar configuration of the magnetic field lines (planar magnetic structure, PMS) due to the compression resulting from the shock itself or from the draping of the magnetic field ahead of the CME.

Gravity waves are fundamental to the dynamics of the mesosphere. In some years very strong winds are observed in the first phase of the MSAO. It has been proposed that this is due to filtering of ascending gravity waves. We report the first gravity-wave momentum flux observations from the Ascension Island (8° S, 14° W) meteor radar and show that anomalous fluxes were observed during one such event in 2002. Analysis of the underlying winds suggests the wave-filtering hypothesis is not valid.