Counter‐Electrojet Occurrence as Observed From C/NOFS Satellite and Ground‐Based Magnetometer Data Over the African and American Sectors

Abstract

An analysis of the counter‐electrojet occurrence (CEJ) during 2008–2014 is presented for the African and American sectors based on local daytime (0700–1700 LT) observations from the Communications and Navigation Outage Forecasting System (C/NOFS) vertical ion plasma drift (equivalent to vertical E×B at an altitude of about 400 km) and ground‐based magnetometers. Using quiet time (Kp≤ 3) data, differences and/or similarities between the two data sets with reference to local time and seasonal dependence are established. For the first time, it is shown that C/NOFS satellite data are consistent with magnetometer observations in identifying CEJ occurrences during all seasons. However, C/NOFS satellite data show higher CEJ occurrence rate for almost all seasons. With respect to local time, C/NOFS satellite observes more CEJ events than magnetometer observations by average of about 20% and 40% over the American and African sectors, respectively, despite both data sets showing similar trends in CEJ identification. Therefore, when a space weather event occurs, it is important to first establish the original variability nature and/or magnitude of the eastward electric field in equatorial regions before attributing the resulting changes to solar wind‐magnetosphere and ionosphere coupling processes since CEJ events can be present even during quiet conditions.

Solar Flux Effects on the Variations of Equatorial Electrojet (EEJ) and Counter-Electrojet (CEJ) Current across the Different Longitudinal Sectors during Low and High Solar Activity

“…On the Our findings indicate that there is a weak or no significant difference in the relation of MCEJs during the period of low solar activity compared to the period of high solar activity in the Peruvian, Brazilian, and Pacific sectors. For Peruvian sectors, our results are in agreement with the previous analysis by Habarulema et al (2019). It also shows a significant decrease of ACEJ in intensities when compared to EEJ at high solar activities indicating an anti-correlation between ACEJ and F10.7.…”

Imprints of Sunspot Cycles on Normal and Abnormal Geomagnetic Fields: Case Study From Equatorial and Low‐Latitude Sites of India

“…The occasional depressions for few hours below the night time values in daily variation in H component at electrojet region during quiet days are associated by westward currents known as counter electrojet (CEJ) (Gouin & Mayaud, 1967). Over the last several decades, extensive experimental and theoretical research has been carried out by several researchers to understand the morphology of EEJ and CEJ phenomena by using ground magnetometer, radar and space measurements (Alken & Maus, 2007;Archana et al, 2018;Chandra et al, 2000;Chandrasekhar & Thinesh Kumar, 2014;Chandrasekhar et al, 2014aChandrasekhar et al, , 2014bChandrasekhar et al, , 2017Doumouya & Cohen, 2004;Forbes, 1981;Gurubaran, 2002;Habarulema et al, 2019;Jadhav et al, 2002;Langel et al, 1993;Luhr et al, 2003;Onwumechili, 1997;Onwumechilli & Agu, 1980;Raghavarao & Anandarao, 1980;Rastogi et al, 2007;Richmond, 1973aRichmond, , 1973bSomayajulu, 1988;Sridharan et al, 2002Sridharan et al, , 2009Sugiura & Poros, 1969;Vineeth et al, 2007Vineeth et al, , 2012, and references therein).…”