characteristics of storm time pulsations at magnetic meridional plane connecting conjugate stations...
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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
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