4 February 2015, Solar-Terrestrial Environment Data Analysis Workshop
UN/Japan Workshop on Space Weather 2015 in FUKUOKA

A report on
the MAGDAS data and EE index
from June 2014 to March 2015

Akiko Fujimoto, Shuji Abe, Teiji Uozumi, Maria Gracita Cardinal, Hiroki
Matsushita, Shun Imajo and Akimasa Yoshikawa
International Center for Space Weather Science and Education, Kyushu University

What is EE-index
 Proposed by ICSWSE [ref. Uozumi et al., 2008]
 Using MAGDAS/CPMN data along the magnetic equator Useful for monitoring temporal or long-term variationsof the EEJ

D = DR + DCF + DS + DP + EEJ/CEJ + …
EWA

EE-index:

EDst(global)

EUEL(local)

EEJ and others
DCF:SSc (Chapman-Ferraro current)

EEJ

DP(Polar Disturbance ): DP2

CEJ

Substorm

DR:Ring current

01

1. Introduction

Stronger EEJ between September and December
during higher activity of Vsw and Dst
2014

EEJ
@BCL

Solar Wind
Velocity(omni)

Dst
Index(omni)

Km/s

Local NoonnTJunJul

Aug

Sep

Oct

NovDecJan

Long term variation EEJ @ BCL (Viet Nam)
Differences between daily peak-EEJ and yearly average peak-EEJ

(A)

Peak
(C)
(B) EEJ / Day

(D)

Avg.
EEJ
Avg. EEJlevel

Enhanced EEJ (A) Jan. – May 15 ,(C) Sep. – Nov. 15

Avg. EEJ
Depressed EEJ(B) My 16 – Aug. , (D) Nov. 16 - Dec .

Long term variation of EEJ at other stations
CDO around the dip equator

BCL both North and South hemisphere The EEJ trend is NOT caused by thegeometrical structure of the earth

TIRAABANC

 What causes the long-term EEJvariations?
 Solar wind structure
Vsw, IMF Bt and Bz, IEFy, F10.7
 Magnetic activity
Kp, Dst, PC index
AAB TIR BCLANCCDOEWAICAICAComparison between EEJ and Solar Wind
EEJ
@BCLVsw

 seem like a most related parameter

Universal TimeEnhanced EEJ
IEFy

Solar windvelocity

Jan. – May 15 402±81 km/s
Sep. – Nov. 15 412±65km/s

IMF BtDepressed EEJ
My 16 – Aug. 356±59 km/s

IMF BzF10.7  slight trend

Comparison with Magnetic Activity Indices
EUEL@BCL

PC index

DstKp

There is no remarkable trend.

The dominant controlling factor in Solar Wind@DAV F10.7 is positively correlatedwith EEJ [Yamazaki et al.,2010JGR] EEJ is enhanced during
eastward IEFy (=SouthwardIMF Bz)

Eastward
IEFy
EEJEarthDependenceof IEFy
During Jan. – May .15 (03 – 05 UT)
(A)

(B)

(C)
In general

EEJ
IEFy [mV/m]

Eastward
IEFy
EEJ

(A)
Depressed EEJ

(B)

(C)

Enhanced EEJ

IEFy[mV/m]Difference between peak-EEJ and averaged peak-EEJ
During the period of the enhanced EEJ,
the interplanetary electric field is negative (=westward IEFy)
Vsw≧400km/s
withEEJ
high-speedsolarwindvelocity.
Difference
from Avg.
EEJ(2014)[nT]
Vsw < 400km/s

DP2 variation on the EEJ
 Average peak EEJ

EEJ @BCL[nT]
Dst Index

 DP2 on the depressed EEJ [Nishida (1968), Kikuchi et al.,(1996)]

Summary The long term variation of EEJ (2014, Jan. – Dec.)-

Both north and south hemisphereDP2 variation also observed in the long-term EEJ

 EEJ dependence on the solar wind velocity (Vsw)-Enhanced EEJ during Vsw ≥ 400 km/s
Depressed EEJ during Vsw < 400 km/s

Enhanced EEJ
Avg. EEJ

Depressed EEJ

Attention!
Realtime EE-index are calculated with non-calibrated data.

Valid only for monitoring purpose

If you need provisional EE-index, which are not final
version but calculated with calibrated data, pleasecontact with PI of MAGDAS/CPMN project.