Inter-annual variations in wave spectrum are examined at 9m water depth from 2009 to 2012 based on measured data. Variations in the wave spectrum are observed inter-annually from January to February, May and October to November due to the changes in wind sea. Average wave spectrum during the monsoon is single peaked; during non-monsoon period, two peaks are observed. Due to sea breeze an increase in spectral energy of the wind-sea part is observed between 15 and 18 UTC from February to April.

A novel data analysis technique for recovering three-dimensional (3-D) magnetic field structures from in situ measurements by two satellites is applied for the first time to a magnetic flux rope observed by the THEMIS spacecraft near the Earth's subsolar magnetopause. We found that the flux rope resulting from multiple X-line reconnection was significantly 3-D and consisted of the field lines with different topologies, suggesting a complex interaction of the solar wind and the magnetosphere.

A vertical coupling process in the northern high-latitude middle atmosphere has been identified during the equinox transitions, which we call the “hiccup” and which acts like a “mini sudden stratospheric warming (SSW)”. We study the average characteristics of the hiccup based on a composite analysis using a nudged model. A comparison of the average characteristics of hiccups and SSWs shows both similarities and differences between the two vertical coupling processes.

A possible link between solar activity and the atmospheric pressure fields is investigated using NCEP/NCAR data at ground level and at 500hPa, in the Northern Hemisphere for the cold season, with a focus on the North Atlantic centres of action. The Icelandic low seems to be most sensitive to the solar signal by moving towards north and by confining its activity area during months with high solar activity.

By performing 3-D MHD simulations including Alfven eigenmode perturbations most unstable to the ionospheric feedback effects, we examined the auroral vortex street that often appears just before substorm onset. We found that an initially placed arc splits, intensifies, and rapidly deforms into a vortex street. We also found that there is a critical convection electric field. The vortex street is shown to be a consequence of M-I coupling between field-aligned currents and Pedersen/Hall currents.

This paper describes the development of empirical models that are capable of predicting Pc3 pulsation intensity from solar wind parameters (e.g. plasma flow speed, proton density, and interplanetary magnetic field (IMF) orientation). We also calculate the typical timescales at which different solar wind parameters influence the excitation of these waves: solar wind speed influences pulsation intensity at much longer timescales (about 2 days) than IMF orientation (about 1 hour).

This paper presents the long-term observations of lunar tidal signatures in the equatorial electrojet (EEJ) and their relation to stratospheric sudden warming (SSW) events. We propose an approach to estimate the occurrence of SSW events before their direct observations (before 1952) from the magnetic field observations at Huancayo.