Impact of Sudden Stratospheric Warming of 2009 on the Equatorial and Low‐Latitude Ionosphere of the Indian Longitudes: A Case Study

• Published in: Journal of geophysical research. Space physics 2017-10, Vol.122 (10), p.10,486-10,501
• Main Authors: Yadav, Sneha, Pant, Tarun K., Choudhary, R. K., Vineeth, C., Sunda, Surendra, Kumar, K. K., Shreedevi, P. R., Mukherjee, S.
• Format: Article
• Language: English
• Subjects: Amplification; Diurnal variations; Electrodynamics; Electrojets; Equatorial electrojet; equatorial ionization anomaly; equatorial ionosphere; Ionization; Ionosphere; Latitude; Lunar tides; Magnetic fields; Perturbation; planetary waves; Stratosphere; Stratospheric warming; sudden stratospheric warming; Tides; Total Electron Content
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1002/2017JA024392

Using the equatorial electrojet (EEJ)‐induced surface magnetic field and total electron content (TEC) measurements, we investigated the impact of the sudden stratospheric warming (SSW) of January 2009 on the equatorial electrodynamics and low‐latitude ionosphere over the Indian longitudes. Results indicate that the intensity of EEJ and the TEC over low latitudes (extending up to 30°N) exhibit significant perturbations during and after the SSW peak. One of the interesting features is the deviation of EEJ and TEC from the normal quiet time behavior well before the onset of the SSW. This is found to coincide with the beginning of enhanced planetary wave (PW) activity over high latitudes. The substantial amplification of the semidiurnal perturbation after the SSW peak is seen to be coinciding with the onset of new and full moons. The response of TEC to SSW is found to be latitude dependent as the near‐equatorial (NE) stations show the semidiurnal perturbation only after the SSW peak. Another notable feature is the presence of reduced ionization in the night sector over the NE and low‐latitude regions, appearing as an “ionization hole,” well after the SSW peak. The investigation revealed the existence of a quasi 16 day wave in the TEC over low latitudes similar to the one present in the EEJ strength. These results have been discussed in the light of changes in the dynamical background because of enhanced PW activity during SSW, which creates favorable conditions for the amplification of lunar tides, and their subsequent interaction with the lower thermospheric tidal fields. Key Points The patterns of EEJ‐induced field and TEC were found to be disrupted significantly before, during, and after the peak SSW Substantial influence of lunar tides was observed during the SSW event Anomalous depletion in nighttime TEC was observed over low latitudes after the SSW peak