Impact of magnetic clouds on the middle atmosphere and geomagnetic disturbances

Magnetic clouds, characterized by high magnetic field magnitude, low proton temperature and plasma beta, and a smooth rotation in the magnetic field direction, cause strong geomagnetic disturbances. In the present paper we study the impact of magnetic clouds on the middle atmosphere and geomagnetic disturbances. We find that the effects of magnetic clouds depend on both the phase of the quasibiennial oscillations of equatorial stratospheric winds, and on the handedness, or direction of rotation, of the magnetic field in the cloud. Strongest influence on the stratosphere both in the Northern and Southern hemispheres has left-handed magnetic clouds in QBO Easterly phase. Effects of magnetic clouds are seen in the mesopause region as well, and their effects on the neutral winds and geomagnetic disturbances also depend on QBO phase and the handedness of the clouds, being strongest again for left-handed clouds in QBO Easterly phase.