Global, low‐latitude, vertical E × B drift velocities inferred from daytime magnetometer observations

Abstract

1] Navigation and communication, Department of Defense and civilian, customers rely on accurate, lowlatitude specification of ionospheric parameters, globally, that are not currently realistic on a day-to-day basis. This paper describes, demonstrates, and speculates about the data sets that are required inputs to the operational ionospheric models that will correct these deficiencies. In order to investigate quiet time, vertical E Â B drift velocities at two different longitude sectors, magnetometer observations were obtained for the period between January 2001 and December 2004 from the magnetometers at Jicamarca (0.8°N dip latitude) and Piura (6.8°N dip latitude) in Peru and from Davao (1.4°S dip latitude) and Muntinlupa (6.3°N dip latitude) in the Philippine sector. We choose only geomagnetically ''quiet'' days, when the 3-hourly Kp value never exceeds a value of 3 over the entire day, and when the daily Ap value is less than 10. These are ''binned'' into three seasons, December solstice, equinox, and June solstice periods. A neural network trained for the Peruvian sector was applied to each of the days in both the Peruvian and Philippine sectors, providing DH-inferred vertical E Â B drift velocities between 0700 and 1700 local time. For each season, the average E Â B drift velocity curves are compared with the Fejer-Scherliess, climatological E Â B drift velocity curves in both the Peruvian and Philippine sectors. In the Peruvian sector, the comparisons are excellent, and in the Philippine sector they are very good. We demonstrate that realistic magnetometerinferred E Â B drifts can be obtained in the Peruvian sector on a day-to-day basis and speculate that on the basis of the average, quiet day comparisons, realistic E Â B drifts can be obtained on quiet days in the Philippine sector.

The longitudinal variability of equatorial electrojet and vertical drift velocity in the African and American sectors

“…The magnitude and direction of the dayside vertical velocity (E × B drift) can be easily estimated using pairs of ground magnetometers around the dip equator (Anderson et al, 2004(Anderson et al, , 2006Yizengaw et al, 2011Yizengaw et al, , 2012. The equatorial electrojet current (EEJ) produces a strong enhancement in the H component magnetic field measured by magnetometers located within ±3 • of the magnetic equator.…”

Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

“…numerically validated the linear relationship between the F-region vertical plasma drift velocity and the difference in the H -component magnetic perturbations at equatorial and off-equatorial stations for different levels of solar activity. Anderson et al (2006) suggested that the empirical formulae derived from the Peruvian observations can be applied to the magnetic data from the Philippine longitude sector. Similarly, applied the technique to the data from the Indian longitude sector, and Yizengaw et al (2011Yizengaw et al ( , 2012 to the data from the African longitude sector.…”

The equatorial ionospheric response over Tirunelveli to the 15 January 2010 annular solar eclipse: observations

“…Ground-based magnetometer observations of electrojet strength data during daytime have been extensively used to demonstrate the vertical E × B drift velocity in the equatorial F region in the Peruvian, Filipino and Indian longitude sectors under quiet and disturbed condition during 07:00 and 17:00 IST (Anderson et al, 2006, and references therein). Quiet time H -inferred E × B drift velocities are in excellent agreement with the Fejer-Scherliess, quiet time, climatological daytime E × B drift model (Scherliess and Fejer, 1999) in the three longitude sectors.…”