Measurement of Short Period Magnetic Pulsations at Barrow:

A Key Location in the STEP Polar Network

KANJI HAYASHI

The main objective of the Solar Terrestrial Energy Program (STEP) polar network is to realize a high time-resolution global scale network to trap disturbances induced by the solar-terrestrial links that occur somehow like earthquakes. Solar cycle effects found in occurrences of a type of short period magnetic pulsations termed as Pc1, is an unsolved and interesting target for long-term observation.

Magnetic field measurements are obtained at BRW with a highly sensitive (~ 3 pT @ 1Hz) induction magnetometer in operation almost continuously for more than 1 year when a new digital data logger was installed. The installation and the initial settings were carefully managed by the station operators.

Data status: A significant amount of DC offset and its drift in the Y component were observed in warm seasons. It was a known problem of the instrument and was reported that it settled down in the cold season. We guess that connection points along the signal cable going to the Y sensor were probably wet. Electromotive force from the sensor is very low (less than 1 Mv) and is easily overcome by battery effects at wet contacts. It will be fixed in 1996 by checking the cable.

Data release: Acquired data are primarily processed for our research but are provided for any other researchers on request and compressed data is in free access on the Internet via anonymous ftp at "hpgrl.grl.s.u-tokyo.ac.jp." The volume of high resolution data such as acquired at BRW is as much as 130 MB each month on a cassette tape. Whole-month data from about 20 sites (potentially 30 if all work well) is too much to place on the disk for free access, but will be placed on image files that contain frequency versus time display.

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