Characteristics of Storm Time Pulsations at Magnetic Meridional

Plane Connecting Conjugate Stations

Raman Selvamurugan, Ajay Dhar, and Arun Hanchinal

Indian Institute of Geomagnetism, Plot#5, Sec-18, Kalamboli Highway, New Panvel, Navi Mumbai – 410 218, INDIAramselva@iigs.iigm.res.in also at ramanselva_iig@rediffmail.com

Currents above and around the Globe

Magnetic field (IMF) associated with solar wind ( ) - opens the filed lines for the entry of solar wind

Solar wind particles – Influence the Currents – also generates shock waves – that resonate with the earth’s magnetic field

Solar wind pressure = terrestrial pressure of the Magnetic field

Case – IDst = -363 nT

Case – IIDst = -373 nT

Tromso (69 40 N, 18 56 E) Maitri (70 45’ S, 11 42 E)

Caution:

Scales are Different !

Indices

• Interplanetary conditions

Inter planetary Conditions Contd.

Am

plit

ud

e

(nT)

At Maitri ULF pulsations

PC5 pulsations at different latitudes

Locations

Maitri

Pondicherry

Hanley

Continued for Pc6

Continued for longer periods

at different latitudes

During 20th Oct-10th Nov, 2003

At longer periods

Disturbance field amplitude at various time scales

Corresponding to the magnetic storm day

Case – I

Time

Physical conditions at Maitri and other stations

Case II

Q-day Characteristics

The basis for the proposal The phase drift corresponding to sub storm pulsations between

the conjugate pair of stations is found to appear even before a well defined storm occur.

The emphasize remains on the early drift in phase behavior which is found to happen even before the initial phase of the storm.

The phase at these two conjugate stations during the peak of the storm is found to be exactly in out of phase manner.

Subsequently the phase difference gradually decrease between these stations and attains a phase coherence with each other.

The pulsation amplitudes maximizing at 10-30 minutes indicate that the sub storm processes are rather more intense than the storm time field line resonance modes excited by IMF shocks during storm.

Pulsation at different wave disturbance band at different latitude suggests that the field line resonances are more intense at higher latitudes.

Absolute values of earth’s horizontal component seem to relate to the strength of the storm, whereas the phase and amplitude information of a dominant/sensitive time scale disturbances would provide exact time at which the initial, growth and recovery phase of the storm takes place.

What we need to understand!

• How the field line resonances in terms of its amplitude and phase changes as we move from high latitude to low latitude along the same magnetic meridian?

• What are the longitudinal (magnetic!) in equalities in the propagation modes?

• Can we predict the Storm using only the ground based magnetic sensors?

• How Auroral current responds to the storm?

Magnetic field line trace along 150º Meridional plane

Indian Magnetic observatories

Indian Stations along 150 Magnetic Meridians

Existing

Proposed

Moscow

Mys Zhelaniya

Rudolfa

Mumbai

North pole

highest lowest

Jan -10ºC -15º C

Jul 0.0ºc +2.2º C

30 y +13º C -54º C

North pole town

Hobart

Approach to the new location to the

ANTARCTICA STATION highest lowest

Jan 9.2ºC -8.9º C

Jul 1.1ºc -33.2º C

Expedition route to Antarctica

3 axis flux gate sensor, Exciter, LNA, AA-Filter, channeled Analog output from the Sensor

Choosing a flux gate magnetometer

Typical standards that are Required

Bandwidth Dc- 1 Hz

Range ± 70,000 nT

Resolution 0.1 nT

Sensitivity <10.0 pT/Hz

Accuracy 0.1 nT

Long term stability 0.1 nT

power consumption <2.5 W

Op Temp/drift 0.1 nT/C

D/A Converter, Digital Filters

(All the channels)

Data Acquisition standalone hardware/or a PC recording all channels

RS 232/RS485

Data storage

Software/ Hardware Intermediate for monitoring

Interface

Existing Magnetometers and their outputs

• Digital Flux gate H, D, Z or δ X, δ Y, δ Z • DI flux gate D, I• PPM F• Variometers X, Y, Z• Intermagnet (DFM) X, Y, Z, F• dIdD suspended δD, δI, F, or X, Y, Z• Digital magnetometer X,Y,Z• Vector PPM F, H, Z

S No

Type of instrument

Resolution

Range Component measured

Bandwidth Accuracy

Temp Drift/ ºC

Long term drift

Temp range in C/Remarks

1 Intermagnet (standard)

1 nT Base value ±3000 nT

F, δX, δY, δZ, X, Y, Z

DC – 10 Hz 0.1 nT

1 nT

2 DI flux Magnetometer

0.1 nT 0.1 nT- 200,000 nT

D, I DC- 10 Hz 0.1 nT 0.01nT

<0.1 -10 - +50

3 PPM 0.1 nT 70,000 nT F DC-2 MHz 0.1-0.01 nT

0.01 nT

Insensitive to changes in temp

PGR 0.042576 Hz/nT

4 Variometers 0.1 nT 1-60,000 nT X, Y, Z 1 nT

5 Digital Flux gate

0.1 nT Base value ±3000 nT

H, D, Z or δX, δY, δZ,

DC-1 Hz 0.1 nT <0.1 nT

6 dIdD suspended overhauser magnetometer

0.01 nT 20,000-120,000 nT

F, dI, dD or X, Y, Z

DC-5Hz1-5s

0.2 nT 2 nT -40 - +70

7 Digital magnetometer (STL)

0.0002 nT

±80,000 nT – ±100,000 nT

X, Y, Z 0.05 Hz-4 kHz(100µ s-20 s)

<0.1 nT

<0.2 nT

<0.1 nT Temp range?/Mounting?/Sensor alignment

8 Vector PPM 0.1 nT 70,000 nT F, H, Z DC-2 MHz 0.1 – 0.01 nT

Insensitive to changes in temp

Low power acquisition

Wireless acquisition

Budget Requirement

S.No Items I Year (Rs in lakhs)

1. Junior Research Fellow

1.25

2. Cost of running Network of sensors with new installations

15.00

3. Computational equipment

2.25

4. Procurement of magnetometers

45.00

5. Travel 3.00

6. Consumables 0.15

7. Telephone, Fax, Internet charges

0.15

8. Contingencies 1.00

9. Cost of Minor equipment/computer facility upgrading

NA

10. Total 67.80

Thank you