Longitudinal Dependence of Equatorial Irregularities and Electrodynamics!

Transcription

1 Longitudinal Dependence of Equatorial Irregularities and Electrodynamics! Endawoke Yizengaw Institute for Scientific Research, Boston College Special Thanks: M. Magoun, M. Moldwin, E. Zesta, F. Anad, A. Mebrahtu, C. M. Biouele, B. Rabiu, Z. Bamba, O. Obrou, and N. K. Tripathi

2 Outline AMBER instrument deployment status! The longitudinal dependence of EEJ/drift, ionospheric density and irregularity structures! Post midnight irregularities and its longitudinal dependences! Does GIC current significant at the geomagnetic equator?

3 Status of AMBER network expansions AMBER (African Meridian B-field Education and Research) Team members: E. Yizengaw (PI, BC), M. Moldwin (Co-I, UM), E. Zesta (NASA), AMBER Team (different part of the world) Detail Information About AMBER can be found here:

4 Instrument & its Setup at the site Sensor GPS Magnetometer BeagleBoard Belkin UPS Sensitivity: 0.01 nt Resolution: 0.5 sec

5 Data returning procedures Tunnel Server SSH, Port Site UDP, Port 9604 GMAG Viewer SSH, Port 100xx GMAG Server SSH, Port 22 Map it to WWW GMAG Server GMAG Viewer UDP, Port 9605 No more political hassle, i.e., no need to request for firewall issue!

6 Our Database You can search by days, by station You can download ASCII data (1 min, 1 sec, and half sec resolution) You can download summary plots for a quick look!

7 How to estimate drift from Mags. measurements? Magnetometer at off the equator BObs = Bmain+BSQ+BFAC+BRC+BMP Magnetometer at the equator BObs = Bmain+BSQ+BFAC+BRC+BEJ+BMP EEJ, which is generated by Hall and Pederson conductivities at the vicinity of geomagnetic equator (±3 ), is proportional to vertical

8 The longitudinal dependence of EEJ/drift, ionospheric density and irregularity structures

9 Longitudinal EEJ Variations 77 W 69 W 56 W 8 E

10 Longitudinal variability of EEJ & drift

11 Longitudinal Density profiles differences Southern peak Africa-Equator Northern peak Southern peak America-Equator Northern peak

12 Southern peak Africa-Equator Northern peak Southern peak America-Equator Northern peak

13 SWARM Triplet Longitudinal variability Observations

14 Does ESF has the same longitudinal dependence? ç

15 Post-midnight bubbles longitudinal variability ç

16 GIC currents at the Equator

17 Recent investigations of GIC currents at the equator The arrival of interplanetary shocks from the Sun drives strong current systems, which then can destroy our power plants. This kind of impacts are obvious and stronger in high latitude regions. Recently, we demonstrated that such impacts are also stronger in the equatorial regions. Carter & Yizengaw, et al, GRL, 2015

18 Media Coverage about the new investigation Odd Space Weather Leads To Electrical 'Bermuda Triangle' Space Weather and Earth: Equator Power-Grid Effects Space Weather Creates Electrical 'Bermuda Triangles' Jet of Electric Current Boosts Space Weather at Equator Boston College Scientists Uncover Equator s Vulnerability To Space Weather How Space Weather Effects Extend To the Equatorial Regions

19 Summary with lots of open questions! The magnitude and direction of the vertical drift (both dayside and evening sector) show significant longitudinal differences, stronger in the American and Asian than African sectors, what cause this longitudinal differences? Both ground- and space-based observations show clear longitudinal and seasonal variability of bubbles/irregularities structures, stronger in the African sector, which is opposite to the vertical drift longitudinal variability trend. If not the drift that cause the longitudinal bubbles distribution difference, then what could it be? Would it be the neutral winds that cause the long lasting bubbles in Africa? If it is the neutral wind, why the orientation and magnitude of the wind in the African sector is unique compared to other longitudes? Does the GIC current be a concern for nations in the vicinity of the geomagnetic equator? AMBER magnetometer network will be instrumental in estimating the GIC at the equator in different longitudes.

20 General Instrumentation in Africa Seven Years ago This Now!

21 Equatorial Electrojet (EEJ) formation 120 km 100 km ºN 3.0ºN The solar-driven neutral wind results Sq current system and then east-west polarization E-field in the E-region. At the magnetic dip equator, the resulting upward E x B drift moves negative charge at the top and a positive at the bottom of the E-region. The resulting E-field prevents electrons to be drifted further upward, instead, they are propelled westward by the eastward E-field. This forms an eastward electric current flow within ±3.0º of the magnetic equator, which is called the Equatorial Electrojet (EEJ)