Report of the Installation of the Ultra Low Frequency (ULF) Wave by armedman1


									Report of the Installation of the Ultra Low Frequency (ULF) Wave
        Magnetometer System at Sondrestrom, Greenland

                              Hyomin Kim
                          Space Science Center
                       University of New Hampshire

                                 July 2007

                    University of New Hampshire
                             Space Science Center
             Institute for the Study of Earth, Oceans, and Space
                         Morse Hall, 39 College Road
                           Durham, NH. 03824 USA

Principle Investigator:
Mark Engebretson, Augsburg College
Marc Lessard, University of New Hampshire

2-axis search coil magnetometer with GPS time stamping

Date of Installation:
July 9-13 2007

Sondrestrom Incoherent Scatter Radar Facility, Kangerlussuaq, Greenland (67 oN, 309 oE)

Participant for Installation:
Hyomin Kim, Graduate Student, University of New Hampshire
Matthew Argall, Graduate Student, University of New Hampshire

Contact information:
Dr. Mark Engebretson, Co-PI
Department of Physics Augsburg College, 2211 Riverside Avenue, Minneapolis, MN
55454-1338, USA.
+1-612-330-1067 (office) / +1-612-330-1649 (fax)

Dr. Marc R. Lessard, Co-PI
Space Science Center and Department of Physics, University of New Hampshire, 39 Col-
lege Road, Durham, NH. 03824, USA.
+1-603-862-2590 (office) /+1-603-862-0311 (fax)
Paul W. Riley, Research Engineer
Space Science Center, University of New Hampshire, 39 College Road, Durham, NH.
03824, USA.
+1-603-862-2653 (office) / +1-603-862-0311 (fax)

Hyomin Kim, Graduate Student
Space Science Center and Systems Design Engineering, University of New Hampshire,
39 College Road, Durham, NH. 03824, USA.
+1-603-862-1391 (office) / +1-603-862-0311 (fax)

Related links:

1. Overview
Geomagnetic micropulsations are short period (usually of the order of seconds or mi-
nutes) fluctuations of the Earth's magnetic field. They are transitory variations of small
ampltiude (usually less than one part in ten thousand of the Earth's magnetic field) and
leave no permanent effects on the field. Like longer period disturbances, such as magnet-
ic storms, the energy that drives them is of solar origin, in contrast to the Earth's main
field and secular variations which are of internal origin.
         Although the solar induced wave energy in the Earth's enviornment (magnetos-
phere) is a small fraction of the enegry present in the form of plasma and energetic par-
ticles (trapped radiation), waves are most important in the electrodynamics of substorms.
They play a role in: transporting magnetospheric energy to the ionosphere; determing the
life time of trapped radiation; acceleratiing particles either stochastically or in resonance;
and, perhaps, even in coupling the solar wind energy itself to the magnetosphere. The mi-
cropulsation experiment is therefore an important measurement to be made at stations
like Siple, South Pole, McMurdo and Sondre Stromfjord which are the attempting to di-
agnose the magentosphere from the ground.
         The micropulsation detector consists of three (sometimes only two) orthogonal
permeable core search coils and associated analog electronics. The search coils and
preamplifiers are mounted in the ice (or ground) with the Z sensor (up) along the geo-
magnetic field line, the Y sensor (east-west) horizontal and perpendicular to the Z sensor,
and the X sensor (north-south) along the geomagnetic meridian, perpenicular to the Y and
Z sensors.
         The search coils that are used for this project have 160,000 turn coils of number
36 copper wire mounted on 0.8 m long by 2.5 cm diameter annealed mu-metal cores. The
coil gain is 150 uV/(nT*Hz). Preamplifiers (gain = 121) at the coils provide mV signal
levels for transmission to the data acquisition system (bufferboard of the data system gain,
244). Therefore, the system provides the gain of 4.43 V/(nT*Hz). The frequency response
is DC – 2.5 Hz (-3 dB corner frequency). The resolution is approximately 10 pT at a spe-
cified frequency.
         This document is to provide a basic information of the instrument and to describes
the replacement of an old ULF magnetometer system deployed at the Sondrestrom Radar
Facility in Kangerlussuaq, Greenland with a new ULF magnetometer system that has
been recently developed by the University of New Hampshire. A manual for operators is
also described in the last section.

2. Scientific Objectives
The overall objective of the search coil magnetometer efforts at high latitudes has been to
study the coupling of solar wind energy to the magnetosphere and its deposition into the
atmosphere, both on the day side, near the polar cusp/cleft regions, and on the night side,
in the form of aurorae as a result of the substorm process.
        As in our previous work, this project focuses on the three categories of waves in
the middle and upper ULF frequency band:
1) Pc 1-2 (electromagnetic ion cyclotron) wave generation and propagation, both on
closed field lines and in the cusp/LLBL/mantle regions;

2) Pc 3-4 pulsation propagation from its upstream source into and through the dayside
magnetosphere and polar cap and;
3) Irregular wave activity in the upper ULF frequency range (Pi 1), which may arise from
several sources, as a diagnostic of solar wind – magnetosphere coupling and internal
magnetospheric instabilities such as substorms.

3. Instrument Specifications (See Figure 3.1 and 3.2)
- Type of instrument: 2-axis search coil magnetometer
- Magnetic sensor orientation: 2 axes (magnetic N-S and E-W)
- Frequency response: DC-5Hz (-3dB)
- Magnetic sensor sensitivity: 150 microV/(nT*Hz)
- System sensitivity: 4.43 V/(nT*Hz)
- Dynamic range: +/-2.26 nT
- ADC bit resolution: 1 pT*Hz
- System resolution: 10 pT/Hz^-2
- ADC Sampling rate: 10 samples/sec
- GPS timing accuracy: 30 msec
- Date of installation: Sep. 16. 2006

Figure 3.1 ULF search coil magnetometer system assembly. The magnetic sensors are
installed ~400 meters away from station.

Figure 3.2 The search coils have 160,000 turn coils of number 36 copper wire mounted
on 80 cm long by 2.5 cm diameter annealed mu-metal cores.

4. Installation
Researchers from the University of New Hampshire visited the Sondrestrom Incoherent
Scatter Radar Facility in Kangerlussuaq, Greenland from 9th to 13th of July 2007 to re-
place an old ULF magnetometer system with a newly designed one.
        The ULF magnetometer system consists of a two-axis search coil sensor, a data
acquisition electronics with a GPS antenna, and a cable that connects the sensor with the
electronics. A new location for the search coil sensor has been chosen, which is approx-
imately 10 m away from the old ones. The new place is slightly slant compared to the old
one and will therefore provide better water drainage during the season of ground thaw.
Figure 4.1 shows the locations for the old and new sensors. The search coils are buried
approximately 30 cm deep under the ground to keep them from being tampered by any
possible surrounding effect. The old search coils that used to be buried under the ground
and now that have been removed are shown in Figure 4.2. The new search coils have
been deployed in a same way the old ones were placed as shown in Figure 4.3. The cable
is laid out from the sensor location to the station where the electronics is placed. The
length of the cable is approximately 400 m as shown in Figure 4.4. The data acquisition
system is comprised of an electronics enclosure (rack mounted) and a GPS antenna. The
enclosure is mounted on a rack located inside the station building (Figure 4.5) and the
GPS antenna is attached to the overhang of the building roof (Figure 4.6).

Figure 4.1 The locations where (a) the old ULF search coils were placed (now they have
been removed; (b) the new ULF search coils are placed.

Figure 4.2 The old ULF search coils that are now removed.

Figure 4.3 The new ULF search coils that are installed in a new location nearby the old
site. The coils are completely buried after being leveled and oriented.

Figure 4.4 The 400 m long cable that connects between the search coil sensor and the
data acquisition system installed in the station building.

Figure 4.5 Rack-mounted data acquisition system (the black enclosure under the key-

Figure 4.6 GPS antenna attached to the overhang of the building roof.

5. Data archive/Maintenance (See the operator’s manual for more de-
The ULF magnetometer system is free of onsite maintenance under normal conditions. It
is highly recommended, however, that operator check if the magnetic field signals dis-
played on the panel meters of the data acquisition electronics are within the tolerance
range specified in the system manual and the compact flash card placed inside the elec-
tronics is not full (if the card is full, an LED on the panel will turn on). The data acquired
by the system are transferred by UNH’s database system automatically on a regular basis
via FTP.


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