Ionospheric response to CIR‐induced recurrent geomagnetic activity during the declining phase of solar cycle 23

Abstract

This paper presents an epoch analysis of global ionosphere responses to recurrent geomagnetic activity during 79 corotating interaction region (CIR) events from 2004 to 2009. The data used were GPS total electron content (TEC) data from the Madrigal Database at the Massachusetts Institute of Technology Haystack Observatory and the electron density (Ne) data obtained from CHAllenging Minisatellite Payload (CHAMP) observations. The results show that global ionosphere responses to CIR events have some common features. In high and middle latitudes, the total electron content (TEC) showed a significant positive response (increased electron densities) in the first epoch day. A negative TEC response occurred at high latitudes of the American sector following the positive response. The CHAMP Ne showed a daytime positive response in all latitudes and a nighttime negative response in the subauroral region. These negative TEC and Ne responses were found to be related to thermospheric composition (O/N 2 ) changes during the storms. At all latitudes, the maximum of the TEC positive effect always occurred at 2-6 h after the CIR starting during local daytime and 10-18 h later for the CIR onset during local nighttime. Case studies indicate that the TEC and Ne positive response had a strong dependence on the southward component (Bz) of the interplanetary magnetic field and solar wind speed. This suggests that penetration electric fields that were associated with changes in solar winds might play a significant role in the positive ionospheric response to storms. During the recovery time of the CIR-produced geomagnetic activity, the TEC positive disturbance at low latitudes sometimes could last for 2-4 days, whereas at middle to high latitudes the disturbance lasted only for 1 day in most cases. A comparison of the ionospheric responses between the American, European and Asian sectors shows that the ionosphere response in the North American sector was stronger than that in the other two regions. The response of f o F 2 to the CIR events in middle to high latitudes showed a negative response for 2-3 days after the first epoch day. This is different from the response of TEC, which was mostly positive during the same period of time.

Effects of solar wind high‐speed streams on the high‐latitude ionosphere: Superposed epoch study

“…At midlatitudes where electric fields are small, the change in thermospheric composition is probably the most suitable mechanism to explain the f o F 2 decrease observed by Denton et al [2009]. This is well consistent with the observations, where global decreases in the O/N 2 ratio during magnetic storms were reported [Crowley et al, 2008;Zhang et al, 2014;Chen et al, 2015].…”

The geomagnetic storm time response of GPS total electron content in the North American sector

“…Early studies of storm time TEC response were obtained by measuring the Faraday rotation of transionospheric radio signals reflected from the moon [ Evans , ; Taylor , ] and later broadcast by geostationary and low Earth orbit spacecraft [e.g., Hibberd and Ross , ; Klobuchar et al , ; Mendillo , ; Hearn , ; Lanzerotti et al , ; Balan and Rao , ]. More recent statistical studies have used the differential time and phase delay of Global Positioning System (GPS) signals to measure the storm time TEC response over both regional [ Stankov et al , ; Borries et al , ; Chen et al , ] and global scales [ Zhao et al , ; Liu et al , ; Immel and Mannucci , ]. Most TEC studies have found that positive storm effects tend to occur within the first 24 h after onset while the subsequent negative phase may persist for up to several days [e.g., Mendillo , ].…”

“…Seasonal variations in thermospheric circulation often produce stronger and longer‐lasting positive/negative TEC changes during winter/summer [ Liu et al , ], although some studies have reported the largest negative storm effects during equinox rather than in summer [ Mendillo and Klobuchar , ; Stankov et al , ]. The American longitude sector has been shown to exhibit the largest positive storm response in comparison with other geographic regions [ Zhao et al , ; Chen et al , ] due to the local magnetic dipole tilt and proximity to the South Atlantic Anomaly [ Yizengaw et al , ].…”

The observation and simulation of ionospheric response to CIR/high‐speed streams‐induced geomagnetic activity on 4 April 2005

“…The periodic occurrence of CIRs/HSSs and its effect suggest a possibility for forecasting the ionospheric disturbance during recurrent geomagnetic activities. To fully understand the ionospheric behavior during CIR events, further studies are necessary on the characteristic and commonality of the ionospheric response to CIR/HSS‐induced geomagnetic activity [ Wang et al ., ; Burns et al ., ; Solomon et al ., ; Liu et al ., ; Verkhoglyadova et al ., ; Chen et al ., ]. Burns et al .…”