Characteristics of equatorial electrojet revealed by CSES observation

By utilizing the magnetic field measurements from the high precision magnetometer (HPM) onboard the China Seismo-Electromagnetic Satellite (CSES), also called Zhangheng-1, the equatorial electrojet (EEJ) at 14 :00 local time (LT) from August 2018 to December 2019 are investigated in this study. For the selected 4729 electrojet events, the averaged latitudinal profile of current density peaks at the magnetic equator, with a mean peak value of 27 mA. m(-1) This amplitude seems smaller than the previous results derived from the CHAMP and Swarm missions, which should be related to the different solar flux levels for the considered periods and local time. The current is narrow with the half-maximum width of about 4 degrees in latitude. The ratio of the peak current density between the main EEJ and its sideband is about 2. 7. The considered events consist of both eastward and westward EEJ events, with proportions of 83Yi and 17%, respectively. This is slightly different from the earlier results derived from the CHAMP satellite, which is related to the relatively lower occurrence rate of westward EEJ at 14:00 LT. The dependences of the eastward EEJ on longitude, season, and solar activity level are also checked. The averaged EEJ peak current density shows a prominent longitudinal wave number 4 pattern, which should be attributed to the non-migrating tides originated from the lower atmosphere. The EEJ peak current density exhibits a clear dependence on season, showing larger amplitudes in equinox seasons and smaller values for solstice seasons. During the considered period, the EEJ peak current density increases for P-10.7 index ranging from 68 to 77 sfu.