first geomagnetic observation at sabah, malaysia by ...universiti malaysia sabah (ums), sabah. this...

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.



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



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



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)



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



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)).

REFERENCES [1] K. Yumoto and C. Group, “A Review of MAGDAS / CPMN Project

During IHY,” Niger. J. Sp. Res., vol. 8, no. March 30, pp. 349–390, 2010.

[2] K. Yumoto and The 210oMM magnetic observation group, “The STEP 210° Magnetic Meridian Network Project,” J. Geomag. Geoelectr., vol. 48, pp. 1297–1309, 1997.

[3] G. Maeda and K. Yumoto, “Progress Report on the Deployment of MAGDAS,” Earth. Moon. Planets, vol. 104, no. 1–4, pp. 271–276, 2009.

[4] K. Yumoto and S. Sub-committee, “International Heliophysical Year Activities in Japan,” Data Sci. J., vol. 8, no. March, pp. 14–23, 2009.

[5] W. H. Campbell, Introduction to Geomagnetic Fields. Cambridge University Press, 2003.

[6] S. Maus, . Macmillan, S., S. McLean, B. Hamilton, A. Thomson, M. Nair, and C. Rollins, “The US / UK World Magnetic Model for 2010-2015,” 2010.

[7] S. Abe, K. Yumoto, A. Ikeda, T. Uozumi, and G. Maeda, “Data and Information Activities of Icswse , Kyushu,” Data Sci. J., vol. 12, no.



March, pp. 92–96, 2013. [8] W.D.Parkinson, “The Geomagnetic Coast Effect,” Rev. Geophys. Sp.

Phys., vol. 17, no. 8, 1999. [9] J. Jankowski and C. Sucksdorff, “Guide For Magnetic Measurements

and Observatory Practice,” 1996. [10] N. Basavaiah, 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, 1976.

[12] E. López, G. Maeda, K. Vicente, K. Yumoto, N. Vasquez, H. Matsushita, A. Shishime, and C. Vásconez, “First Magdas Equipment in Ecuador,” Sun Geosph., vol. 9, no. 1–2, pp. 31–34, 2014.

[13] S. Chapman and J. Bartels, Geomagnetism, Volume 1. Oxford University Press, 1940.

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].



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]

first geomagnetic observation at sabah, malaysia by ...universiti malaysia sabah (ums), sabah. this...

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