Particularly intense substorms (SSS), brilliant auroral displays with strong >106A currents in the ionosphere, are studied. It is believed that these SSS events cause power outages during magnetic storms. It is shown that SSS events can occur during all intensity magnetic storms; thus power problems are not necessarily restricted to the rare most intense storms. We show four SSS events that are triggered by solar wind pressure pulses. If this is typical, ~30-minute warnings could be issued.

We studied the localized plasma density enhancements called blobs, which are often produced in the high-latitude ionosphere by the transportation process of plasma or particle precipitations. This subject is important because such structures affect radio wave propagation and can cause scintillation of GNSS signals in the deformation process. This paper is the first report of direct observations of blob deformation during a substorm.

This study investigates the long-distance propagation (~ 1200–2000km) of gravity waves in the Indian subcontinent using coordinated nightglow measurements at Allahabad and Gadanki (separated by ~ 12º latitude). On few occasions, an identical wave (period in range ~ 2.2–4.5h) was seen at both sites that shared a common source. Waves had large horizontal wavelength (~ 1194–2746km) and phase speed (77–331m/s). The m2 profile analysis suggests the ducted propagation of the common waves.

High-speed streams of particles from the Sun can cause high-energy electrons to be precipitated into the Earth's middle atmosphere at polar latitudes. The paper develops and tests a model for how these particles can change the amount of a trace gas, nitric oxide, which has the potential to destroy stratospheric ozone. Model calculations agree well with observations by the Odin satellite of increased nitric oxide over Antarctica associated with high-speed solar wind streams.

A rare occurrence of stratospheric cirrus at 18.6km persisting for about 5 days is observed over India from 3 to 7 March 2014. Due to potential vorticity intrusion, large-scale updrafts and increase in humidity are observed at 18.6km. Relative humidity with respect to ice is ~ 150%, indicating that the cirrus cloud may be formed though homogeneous nucleation of sulfuric acid. The persistence of the cirrus cloud is due to the cold anomaly associated with the presence of a 4-day wave.