There are actually a lot of things you can do with the EEJ data! You are right that basic characteristics of the EEJ have been extensively studied in the past. But much of its "variability" is still to be explained. As you may know, the EEJ variability exists even during quiet days. This is because variable atmospheric waves from the lower atmosphere drive electric fields and currents in the ionosphere, which affects the EEJ intensity. Recently, researchers (including me) found that the EEJ is significantly disturbed during stratospheric sudden warming (SSW) events. The SSW is a meteorological phenomena where the polar temperature in the stratosphere suddenly increases during the northern winter. Some related readings are:

Fejer, B. G., M. E. Olson, J. L. Chau, C. Stolle, H. Lühr, L. P. Goncharenko, K. Yumoto, and T. Nagatsuma (2010), Lunar-dependent equatorial ionospheric electrodynamic effects during sudden stratospheric warmings, J. Geophys. Res., 115, A00G03, doi:10.1029/2010JA015273.

Yamazaki, Y., A. D. Richmond, and K. Yumoto (2012), Stratospheric warmings and the geomagnetic lunar tide: 1958–2007, J. Geophys. Res., 117, A04301, doi:10.1029/2012JA017514.

The SSW occurs almost only during northern winter months, thus doesn't explain the EEJ variability during the northern summer. It would be interesting to compare the EEJ data with meteorological data (such as NCEP/NCAR reanalysis) for the periods when there is no SSW.

Also, other researchers found that the El Nino-Southern Oscillation has an impact on the low latitude ionosphere, but its effect on the EEJ is not studied yet. For example:

Pedatella, N. M., and J. M. Forbes (2009), Interannual variability in the longitudinal structure of the low-latitude ionosphere due to the El Niño–Southern Oscillation, J. Geophys. Res., 114, A12316, doi:10.1029/2009JA014494.

I hope you got some ideas from my comments.

YY

The work dépends of the location of the stations.

If there is one station at latitude 6-9° of the dip equator, you can compute the electric field., see the work Anderson et al. (2004) and Anderson et al. (2006).

There are a number of things that can be done, but first be aware that data from a great many magnetometer stations are freely available, for example through the Super MAG site: http://supermag.jhuapl.edu/. If you have digital data sampling with accurate timing and good time resolution then you could, for example, examine the properties of ULF waves at low latitudes, especially how they vary with local time. It is well known that these waves are produced by a range of mechanisms in the solar wind or outer magnetosphere but there is not much information on how these waves propagate to very low latitudes.

In particular Pc5 waves are ubiquitous at high latitudes but there is still controversy on whether they result from solar wind pressure variations, or resonances, cavity or waveguide modes in the magnetosphere. Information on their occurrence and properties (e.g. polarization) at low latitudes may help, especially when compared with higher latitude observations.

In addition, Pc3-4 ULF waves propagating through the magnetosphere may couple to field line resonances, but there is a low-latitude limit for this. The question then arises how these waves reach lower latitudes. Observed wave properties at very low latitudes (especially phase and polarization) are modified by the EEJ, but more detailed knowledge is required.

Finally, I suggest you contact E. Yizengaw, who operates a NASA-funded network of very low latitude magnetometers in Africa. See: https://www2.bc.edu/endawoke-kassie/AMBER.html.

You may already know of the forthcoming African Geophysical Society meeting in Nigeria in June: http://afgps.org/conference/

Following are some references that may be helpful.

Villante et al., Pc5 geomagnetic field fluctuations at discrete frequencies at a low latitude station, Annales Geophys., 19, 321-325, 2001.

Marin et al., Global Pc5 pulsations during strong magnetic storms: excitation mechanisms and equatorward expansion, Annales Geophys., 32, 319-331, 2014.

Trivedi et al., Global Pc5 geomagnetic pulsations of March 24, 1991, as observed along the American sector, Geophys. Res. Lett., 24, 13, 1683-1686, 1997.

Feng et al., Pc3-4 geomagnetic pulsations observed at very low latitude conjugate stations, J. Geophys. Res., 100, A10, 19287-19298, 1995.

Best wishes

Fred

To Yosuke Yamazaki: You response is very interesting. i have been working on EEJ over the East African region and i have learnt of very intense EEJ that has nothing to do with convective fields due to storm. You mention of SSW events as a cause of the EEJ variability is something am interested in. So how do you access data on SSW events. could you kindly send me your observation on the same for 2012-11-16

To O.J. Olwendo: Thank you for your message. I will send to you data for the arctic polar temperature at 10 hPa (~32 km height), privately. Those data from NCEP/NCAR reanalysis, and the original data can be downloaded from its website at: http://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.html

There was a strong SSW event in January 2013 as reported by Goncharenko et al. (2013). This is something you may want to check in your data.

Goncharenko, L., J. L. Chau, P. Condor, A. Coster, and L. Benkevitch (2013), Ionospheric effects of sudden stratospheric warming during moderate-to-high solar activity: Case study of January 2013, Geophys. Res. Lett., 40, 4982–4986, doi:10.1002/grl.50980.

16 Nov 2012 is right after a minor storm on 14 Nov. I would suspect 'after-storm effects', first. Such effects are sometimes very strong for some reasons. Good examples can be found in this paper:

Le Huy, M., and C. Amory-Mazaudier (2005), Magnetic signature of the ionospheric disturbance dynamo at equatorial latitudes: “Ddyn”, J. Geophys. Res., 110, A10301, doi:10.1029/2004JA010578.

To Adekoya, I am glad on the interest you have developed in the electrodynamics of the ionosphere. Like Prof Christine pointed out, one of the two magnetometer stations has to be within +-3 deg mag eqtor, and the other within +-(6-9 deg) off mag eqtor. As the challenge of availability of radar (ISR) measurements in Africa subsists, we can make do with EEJ in determining EXB drifts over the stations of interest. Although, PRE may not be too obvious due to its evening occurrences. In addition to the references given by Christine, see other papers by Endawoke (Yizengaw et al., 2011 JASTP; 2012 JGR; 2014 ANGEO). Please, call me in case of further assistance.

I hope you will find these comments useful.

Best of luck!

I understand about EEJ , but how can i take data of EEJ .