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SITI NURBAITI IBRAHIM et al: FIRST GEOMAGNETIC OBSERVATION AT
SABAH, MALAYSIA BY USING …
DOI 10.5013/IJSSST.a.17.41.30 30.1 ISSN: 1473-804x online,
1473-8031 print
First Geomagnetic Observation at Sabah, Malaysia by using MAGDAS
Array
Siti Nurbaiti Ibrahim1*, Mohamad Huzaimy Jusoh 1,2, Ahmad Asari
Sulaiman1,2, Siti Noor Aisyah Ahmad1, Mohd Zul Hilmey Makmud3, Baba
Musta3, Mardina Abdullah4,5, Mhd Fairos Asillam6 , Nyanasegari
Bhoo
Pathy6, Mohd Helmy Hashim6, Yoshikawa Akimasa7
1 Faculty of Electrical Engineering, Universiti Teknologi MARA
Malaysia, Selangor, Malaysia. 2 Applied Electromagnetic Research
Group, Advance Computing and Communication Communities of Research,
Universiti Teknologi MARA Malaysia, Selangor, Malaysia.
3 Faculty of Science and Natural Resource, Universiti Malaysia
Sabah, Sabah, Malaysia. 4 Department of Electrical, Electronics and
Systems Engineering, Universiti Kebangsaan Malaysia, Selangor,
Malaysia
5 Space Science Center, Selangor, Malaysia. 6 National Space of
Agency of Malaysia (ANGKASA), Malaysia Space Center, Selangor,
Malaysia.
7 International Center for Space Weather Science and Education
(ICSWSE), Kyushu University, Fukuoka, Japan. 7 MAGDAS /CPMN
Group
* Corresponding author: [email protected],
[email protected].
Abstract — MAGDAS (Magnetic Data Acquisition System) is a
magnetometer initiated by Kyushu University used to study space
weather. The latest of real-time Magnetic Data Acquisition System
of Circum-pan Pacific Magnetometer Network was successfully
installed at University Malaysia Sabah (UMS) Sabah, Malaysia by
International Center for Space Weather Science and Education,
ICSWSE, Kyushu University, Japan. This is the second magnetometer
under MAGDAS after Langkawi station (LKW) (geographic latitude and
longitude: 6.30º, 99.78º and geomagnetic latitude and longitude:
-2.32º, 171.29º). This paper reports on first analysis of
geomagnetic observation of MAGDAS at Sabah station. The geomagnetic
components: H, D, Z and total F obtained from MAGDAS’s magnetometer
are presented. The diurnal variation of geomagnetic elements during
initial measurement at Sabah indicates a good variation pattern.
The validation of amplitude variation with the nearest station also
significantly relative. Keywords - component; MAGDAS/CPMN;
geomagnetic magnetometer; ICSWE.
I. INTRODUCTION International Center for Space Weather Science
and
Education, ICSWSE (the new name for Space Environment Research
Center, SERC), Kyushu University, Japan has introduced a real-time
Magnetic Data Acquisition System of Circum-pan Pacific Magnetometer
Network, i.e. MAGDAS/CPMN for space weather study and application,
which was deployed for the International Heliophysical Year (IHY;
2007-2009) [1][2][3]. By using this system, the scientific purpose
that can be conducted are; real-time
monitor and modeling of (1) global 3-dimensional current system,
(2) plasma mass density, and (3) penetrating process of polar
electric fields into the equatorial ionosphere, in order to
understand the Sun-Earth coupling system and the electromagnetic
and plasma environment changes [4].To date, MAGDAS/CPMN have three
(3) unique chains of magnetic observatories; the most magnetometers
were densely installed at 210º magnetic meridian, on African
longitude-sector and the other one is on the sector along the
magnetic equator as shown in Figure 1. Currently, 73 stations are
actively operating.
Figure 1: MAGDAS/CPMN (MAGnetic Data Acquisition System/
Circum-pan Pacific Magnetometer Network) system.
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A. Installation of MAGDAS in Malaysia. On year 2007, The
International Heliophysical Year
(IHY) was declared by the United Nations Office for Outer Space
Affairs (UNOOSA). The IHY is an international program that is used
to study the physical interaction process of Sun and heliosphere
system. For that purpose, the SERC was collaborated with Institute
of Space Science (ANGKASA) and Universiti Kebangsaan Malaysia (UKM)
to install MAGDAS’s magnetometer in Malaysia. On 4th September
2006, the first magnetometer was installed in Malaysia which is
located at the Langkawi National Observatory (LNO), Langkawi. The
geographic and geomagnetic coordinates of Langkawi station are
(6.30º, 99.78º) and (-2.32º, 171.29º) respectively. The LNO station
was selected to locate a MAGDAS instrument due to their location
that nearest to the magnetic equatorial and low disturbance from
any human activity. Next installation of second MAGDAS’s
magnetometer in Malaysia is situated at Universiti Malaysia Sabah
(UMS), Sabah. This station was selected to install a MAGDAS-9
magnetometer due to a few requirements as follows: (1) to fill in
observation gap between Davao (DAV) station in Philippines and
Manado (MND) station in Indonesia for precise geomagnetic
measurement of 210º magnetic Meridian, (2) it is located in
equatorial regions and near to geomagnetic equator as shown in
Figure 2. Table 1 shows the geographic and geomagnetic coordinates
for both stations.
Figure 2: Location of both stations (LKW and SBH) near to
geomagnetic
equator.
TABLE I. THE COORDINATES LOCATION OF LANGKAWI AND SABAH
STATIONS.
Station Abbreviation
Geographic coordinate
Geomagnetic coordinate
Latitude (º)
Longitude (º)
Latitude (º)
Longitude (º)
Langkawi LKW 6.30 99.78 -2.32 171.29
Sabah SBH 6.02 116.07 -2.07 187.35
II. EARTH‘S MAGNETIC FIELD
A. Earth’s magnetic field components The Earth’s magnetic-field
components can represent in
three-dimensional vector as shown in Figure 3. The vectors can
be describe in two means: 1) X, Y and Z (XYZ-components) 2) H, D
and Z (HDZ-components). The X, Y and Z components can be defined as
the geographic direction of Northward, Eastward and Vertical (into
the Earth). For H, D and Z components, it can be represent as (H)
is a horizontal field component, (D) is declination or an angle
between geographic northward to horizontal component and (Z) is a
vertical downward component. Data provided in MAGDAS are typically
in HDZ elements. The total magnetic field intensity is (F) while
(I) is the inclination which is the angle between the horizontal
plane (H) to the total field, (F) [5].
Figure 3: Magnetic-field components in three-dimensional
vector.
The values of geomagnetic elements can be obtained in
simple geometry as follows: )cos(DHX (1)
)sin(DHY (2)
The declination angle D in unit of degrees (º) can be changes
into a unit of nanoTesla (nT) by formula obtained from:
)tan()( DHnTD (3) The total field strength, F is given by:
22222 ZHZYXF (4) The unit of magnetic field intensity is
expressed in
nanotesla (nT). The inclination or dip angle, I can be obtained
by:
)tan(IHZ
(5)
LANGKAWI STATION
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B. Earth’s Magnetic Model To validate the observation of
geomagnetic components,
the results were compared with the World Magnetic Model (WMM) as
a reference which are a standard model of Earth’s core and crustal
magnetic field [6]. This mathematical model is created by the U.S.
National Oceanographic and Atmospheric Administration’s National
Geophysical Data Center (NOAA/NGDC) and the British Geological
Survey (BGS). It is extensively used for navigation and heading
system. The WMM manifests a prediction of magnetic declination in
all over the globe. Furthermore, this model provides geometry
between altitudes of 1 kilometer below the surface to 850
kilometers above the surface of the Earth. In this paper, the
WMM2010 is used to compare with the results of measurements due to
the observation in the years 2013 and 2014. This model is valid for
5 years from 1st January 2010 to 31st December 2014. The maps of H,
D, Z, F and I components are illustrated in the Mercator projection
(see Appendix).
III. OBSERVATION SETUP
A. Overview of MAGDAS-9 System MAGDAS-9 (MAG-9) unit (Figure 4)
consists of 3-
component ring-core fluxgate type magnetic sensor (magnetometer)
with 7 meter cable, pre-amplifier (preamp), GPS (Global Positioning
System) antenna with cable, data logger for data control and 70
meter cable. The parts of magnetic field, slope, and temperatures
are water- and drip- proof for outdoor use. Data logger acts as a
main unit to control the power supply to the unit and communication
process. Magnetic field digital data (H + δH, D + δD, Z +δZ) are
obtained with the sampling rate of 10 Hz, and then 1 second and 1
minute averaged data are recorded and transferred from the oversea
stations to the ICSWSE, Japan in real-time. The ambient magnetic
field, expressed by H (Geomagnetic Northward), D (Geomagnetic
Eastward) and Z (Vertical Downward) components, are digitized by
using the field-canceling coils for the dynamic range of ± 70,000
nT/32 bits. The magnetic variations (δH, δD, δZ) data are further
digitized by the A/D at preamp by 24 bits and 10 Hz resolution and
sampling frequency respectively. The long-term inclinations (I) of
the sensor axes are measured by built in digital tilt meter with
0.1 arc-sec resolution at calibrated accuracy ± 0.25 degree (± 900
sec. degree).
The temperature (T) are also measured at both sensor and preamp
with resolution 0.01°C. The system synchronizes the time of
acquisition of the A/D conversion and the GPS clock transmitted a
pulse of 1 PPS from the GPS module. These data are logging in the
Compact Flash Memory Card of 2 GB [7].
Figure 4: The components of MAGDAS-9 magnetometer system
[7].
B. Installation of MAGDAS-9 at Sabah’s station On 17 March until
21 March 2013, an installation of
latest of MAGDAS’s magnetometer (MAGDAS-9) has been done at
Universiti Malaysia Sabah (UMS), Sabah, Malaysia. Before install
the magnetometer, the placement of instrumentation are important in
order to avoid a noise. The criteria of placement including (1) a
distance from the sea is more than 1000 meters for ideal distance
to minimize noise and avoid the island effect[8], and (2) distance
from building and road is more than 100 meters to minimize the
noise from human activities (man-made and equipment)[9]. For this
installation in Sabah, the sensor hut is located far from the
building which is around 270 meters from the nearest building, 600
meters from the sea and 350 meters from the main road. The location
of MAGDAS-9 at Sabah is presented in Figure 5.
Figure 5: Location of MAGDAS’s magnetometer installed at
Sabah.
Basically, the arrangements of MAGDAS’s
magnetometer are presented in Figure 6. Starting from sensor,
pre-amplifier, data logger and end with database that store the
recorded data. These instruments are placed inside the hut and
small building for protection from bad weather and security
purpose.
Figure 6: Arrangements setup of Magdas’s magnetometer
SensorData
Logger Pre-
Amplifier Database
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The architecture design of MAGDAS-9 at Sabah station
is illustrated in Figure 7. The small building is where the data
logger and GPS are placed and it is connected to Hut 1 or where the
pre-amplifier are setup. The sensor hut is where
the magnetometer had installed. The ideal distance between the
small building and pre-amplifier is 50 meters to 60 meters. Then,
the pre-amplifier is connected to the sensor hut (Hut 2) with the
distance about 5 meters.
Figure 7: Architecture diagram of MAGDAS setup at Sabah.
IV. RESULTS
A. First observation at Sabah’s station In this paper, the
preliminary result of geomagnetic
components; H, D, Z and total F obtained from the first MAGDAS
measurements at Sabah station are reported. Figure 7 shows
geomagnetic observation obtains using MAGDAS-9’s magnetometer from
21 March 2013 until 26 March 2013.
Based on Figure 8, the variation of H, D, Z and total F for a
few days after the installation shows a similar pattern and
consistent for each component. The values of geomagnetic components
varied as follows: a) H-component: from 4.04x104 nT until 4.065
x104 nT, b) D component: from -40 nT until 20 nT, c) Z component:
from -1900 nT until 1800 nT, and total F component: from 4.045x104
nT until 4.07 x104 nT. Based on WMM2010 model, these values of H,
D, Z components are indicate approximately similar to the model
(see Appendix). In this model, Malaysia is situated in ranges of
between ±40000nT for H and F elements. The obtained values of
geomagnetic elements of H and F are also almost identical. These
results can relate to the main field of inclination (I) of WMM2010
(see Figure 15 in Appendix) and the formula of inclination, I by
[10]:
FHI cos (6)
where the degree value of inclination is approaching zero for
this Sabah area. Thus, the results of cos I could be attributed to
the identical value of H and F components.
Figure 8: Geomagnetic data obtain from the MAGDAS-9’s
magnetometer
from 21 March 2013 until 26 March 2013; a) Horizontal (H)
component, b) Declination (D) component, c) Vertical downward (Z)
component and d)
Total field (F) component.
a)
b)
c)
d)
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Next is the diurnal variation from this magnetic
observation after the installation was investigated as shown in
Figure 9. These results are obtained from preliminary observation
on 22 March 2013.
From Figure 9, the diurnal variation of geomagnetic
components H, D, Z, and F are identified in 24 hours of local
time (LT). The amplitude of each geomagnetic element indicates
increments during daytime from 0800LT until 1400LT. The peak time
hour indicates the highest amplitude of geomagnetic components
recorded during that hour which is usually during a noontime.
For H component, the highest peak value is 4.058x104
nT during noontime (1100LT to 1200LT).The amplitude of
declination (D) component during peak hour (1200LT) is approaching
to 0 nT. The highest amplitude for the Z component is -1830nT at
1400LT peak hour. As for F element, the amplitude and peak hour is
almost identical with H element. During night-time, the variation
of geomagnetic components is maintained from 1900LT to 0630LT. The
difference amplitude variations between daytime and nighttime for H
and F components is similar which is about 130nT.
B. Geomagnetic variations at Sabah and Langkawi stations The
variation of geomagnetic elements from Sabah
station are compared with the established nearest station to
check their amplitude variations where the values are apparently
almost similar. Figure 10 are presented the results of comparison
variation between Sabah station and Langkawi station of each
components H, D, Z and F. These results are obtained on March 2014
during quietest day to avoid magnetic event on these variation. The
observations was applied on 15 March 2014 until 18 March 2014. The
blue line indicates a variation of Sabah station while red line
indicates a variation from Langkawi station. From this figure, the
values of amplitude H is different but almost proximate between
Sabah and Langkawi station. The value of H components from Langkawi
station were identified higher compared with Sabah station. The
range value of H components for Sabah is 4.04x104 nT until 4.07
x104 nT while for Langkawi station is 4.14x104 nT until 4.17 x104
nT.
As shown in Figure 10, the values of D component and Z component
from Sabah station is higher compared with Langkawi station.
Comparatively, the D component of Sabah is in positive value
(average 360nT) while for Langkawi is negative values (average
-270nT). The different sign is due to the direction of measurement
where the positive values obtained at Sabah is considered measured
from east of true North while the negative values obtained at
Langkawi is measured from West. For the value of Z component
obtained in Sabah is range from -1700 nT until -1750 nT compared to
Langkawi the range values is -2350nT until -2400nT.
Based on Figure 10(f), the amplitude values of F obtained from
Langkawi is higher than the amplitude values obtained from Sabah.
However, these values from both stations are not quite different
due to the degrees of stations located. Referring to Figure 14 (see
Appendix), the main field intensity of the Mercator projection
shows that the intensity at Langkawi station is about 40000nT as
compared to Sabah station intensity that approaching to 45000nT.
These results also show the amplitude values of F
Figure 9: Diurnal variation of geomagnetic components on 22
March 2013; a) Horizontal (H) component, b) Declination (D)
component, c) Vertical
downward (Z) component and d) Total field (F) component
a)
b)
c)
d)
Peak Time
Peak Time
Nighttime
Nighttime
Daytime
Daytime
Peak Time
Nighttime Daytime
Peak Time
Nighttime
Daytime
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component are almost identical with their H component for both
stations.
Figure 10: The variation of geomagnetic components of Sabah and
Langkawi stations respectively; a) Horizontal (H) component, b)
Declination (D)
component, c) Vertical downward (Z) component and d) Total field
(F) component.
V. DISCUSSION The first observation of variation of geomagnetic
data
obtained at Sabah station shows a good representation of
geomagnetic elements. The diurnal pattern also significantly
increased during daytime and maintained during night-time. These
observations seem consistent with previous studies of [11] and
[12]. These results could be attributed by ionospheric dynamo[13].
The diurnal variation of H component is corresponds with the
flowing of ionospheric current in the E-layer of ionosphere. The
electron density of E-region increased on dayside when exposed to
the solar radiation, hence the magnetic variation is increased.
During night-time, since no solar radiation, the ionospheric
electric current is not flowing and cause low electron density in
the ionosphere layer. Therefore, the night amplitudes also shows
same variation pattern.
VI. CONCLUSION A real-time MAGDAS-9 magnetometer was
successfully
installed at Sabah on March 2013. The observation of geomagnetic
components of Sabah station was conducted. The results of data plot
obtained at Sabah station has shown a reliable pattern of
geomagnetic elements. The amplitude variations for each components
also proximate with near station and a standard model. Hence, the
data observed from Sabah station are acceptable to be analysed.
Furthermore, this observation can show characteristics of
geomagnetic variation in equatorial region and geomagnetic
equator.
ACKNOWLEDGMENT The authors would like to thank International
Center for
Space Weather Science and Education (ICSWSE) for providing
MAGDAS’s instrumentation and assists the installation. The authors
also want to acknowledge the National Space Agency of Malaysia
(ANGKASA-MOSTI) and Universiti Malaysia Sabah (UMS) for the
contribute assisting during installation and provide the location
for the installation of MAGDAS magnetometer. This study was
supported by the Ministry of Higher Education (MOHE) Malaysia and
Universiti Teknologi MARA, Malaysia under grants FRGS (600-RMI/FRGS
5/3) (140/2014)) and RAGS (600-359 RMI/RAGS 5/3) (155/2014)).
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[5] W. H. Campbell, Introduction to Geomagnetic Fields.
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and Information Activities of Icswse , Kyushu,” Data Sci. J., vol.
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March, pp. 92–96, 2013. [8] W.D.Parkinson, “The Geomagnetic
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Geomagnetism: Solid Earth and Upper Atmosphere
Perspectives. Springer Netherlands, 2012.
[11] R. G. Rastogi, “Quiet day variation of geomagnetic H-field
at low latitudes,” J.Geomag. Geoelectr., vol. 28, pp. 461–479,
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[12] E. López, G. Maeda, K. Vicente, K. Yumoto, N. Vasquez, H.
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APPENDIX
The Mercator projection of World Magnetic Model 2010 (WMM2010)
of H, D, Z, F and I are presented in the Figures 11, 12, 13, 14 and
15 respectively. The Mercator projection of the map is range
between 70ºS and 70ºN of geomagnetic latitude and longitude.
Figure 11: The Mercator projection of main field horizontal
intensity (H) with red line contour interval is 1000 nT. Malaysia
is located in range 40000 nT above of horizontal element
intensity.[6]
Figure 12: The Mercator projection of main field declination (D)
with contour interval is 2º. The colors contours represents as red
positive (east); blue
negative (west) and green (agonic) zero line. Malaysia lies near
to green zero line (0º) [6].
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Figure 13: The Mercator projection of main field down component
(Z) with contour interval is 1000nT. The colours contours are
represent red positive
(down); blue negative (up); and green zero line. Malaysia is
lies on -15000 nT to 20000 nT.[6].
Figure 14: The Mercator projection is main field total intensity
(F) with contour interval is 1000 nT. Malaysia is situated in
ranges between ±40000 nT [6].
Figure 15: The Mercator projection of main field inclination (I)
with contour interval 2º. The color contour represents as red
positive (down); blue negative
(up) and green is zero line. Malaysia is near to 0º [6]