Unmanned Observation in Autarctica (I) : Development of an Unmanned Observatory and Preliminary Result of Geomagnetic Variatios Recorded at the Observatory

Abstract

It was planned to set up several unmanned upper atmosphere observatories in the area around Mizuho Station (70°42' S, 44°20' E) in Antarctica during the period of 1976-1978 for the IMS (International Magnetospheric Study). The first unmanned observatory, situated between Mizuho and Syowa Stations in Antarctica, was set up on May 30, 1977 by the wintering party of the 18th Japanese Antarctic Research Expedition. Observation of geomasnetic variations at this observatory was carried out from May 30 to August 23, 1977. The unmanned observatory consists of the following parts. 1. Wind-driven generator Two wind-driven generators (DYNA Technology Co., model 1222H) are used for keeping batteries and instruments warm. Each generator can supply electric power of～200 W on an average when the wind blows continuously at a speed of～10 m/s. 2. Heat insulation boxes Batteries and instruments are put in two heat insulation boxes. The boxes protect the batteries and instruments from low temperature and heavy snow in Antarctica. The wall of these boxes is made of veneer, aluminium plate and styrofoam plate with a thickness of～10 cm. Using thermostats and heaters (200 W for the battery box and 100 W for the instrument box), the temperature inside the boxes can be kept from 0℃ to 10℃ near Mizuho Station throughout the year. 3. Instrumentation Fluxgate type magnetometer Component : H, D, Z components Sensitivity : 10 nT/mm on the chart record Range : ±1250 nT Power consumotion : +18 V/100 mA, -18 V/60 mA Timing : Chronometer (stability 10^8) 4. Recorder The heat pen recorder is used. The data observed at the unmanned observatory are recorded on a chart which is replaced every three and half months. A specification of the recorder is as follows. Available chart width : 250 mm (±1250 nT) Recording speed : 30 mm/h Power consumotion : +18 V/670 mA, -18 V/100 mA 5. Battery Layer-built air cells are used for power supply to the instruments. In this report, results of the environmental test of these facilities in a lowtemperature room are given in detail. Furthermore, magnetic variation data obtained from the unmanned observatory are presented