Instruments

• Introduction
• Riometers
• Magnetometers
• Searchcoil Magnetometer
• Fluxgate Magnetometer
• Optical Instruments

Introduction

The projects that operate from instrumentation at South Pole Station, and at the Arrival Heights Laboratory at McMurdo Station, examine natural phenomena occuring in the earth's atmosphere and magnetosphere. The broad focus of these science programs is toward improved understanding of the mechanisms that couple solar processes into the terrestrial environment; these include investigations of phenomena associated with short-term environmental effects (auroras, induced electrical currents, radiowave communications interference), as well as those associated with longer-term effects (changes in the ozone layer, atmospheric composition studies, stratospheric winds, weather, and even climate). Instruments for these tasks include optical and radio devices for remote sensing, as well as sensors that monitor changes in the electric and magnetic fields at the station; the instruments that measure local fields (including VLF receivers) are sensitive to perturbations that propagate from remote generation regions.

For many investigations, South Pole represents a unique site for studying environmental phenomena. In the case of atmospheric studies this must be obvious, because of the location remote from contaminating sources; in addition to monitoring current atmospheric parameters, ice-coring experiments provide information about past atmospheres. However, the station is also uniquely situated for investigations associated with magnetospheric phenomena. An important region of the earth's magnetosphere separates processes associated with polar cap environments, from those normally related with auroral activity. Polar cap effects are associated with magnetic field lines that connect almost directly with the solar magnetic field on the dayside (cusp/cleft), and with the deep tail of the magnetosphere on the nightside. The boundary between the polar cap and those regions of the magnetosphere associated with closed magnetic field lines is coincident with the auroral oval, so-named because of the frequent occurrence of auroral arcs inside a narrow band around the magnetic pole. The 'polar cap' designation is normally applied to phenomena that occur poleward of the oval, so that the dayside cusp/cleft is regarded as a separate region with properties distinct from either the polar cap or auroral/sub-auroral regions.

McMurdo Station, at invariant magnetic latitude of about 80 degrees, lies inside the polar cap at all local times. Since the magnetic pole is displaced from the geographic pole, South Pole Station is located at an invariant latitude (74.25 degrees) that places the station equatorward of the nominal undisturbed auroral oval on the dayside, and poleward of the oval (in the polar cap) on the nightside; consequently at dawn and dusk the station passes underneath the oval. Under disturbed magnetic conditions the characteristics of the oval, and indeed the entire magnetosphere, experience dramatic changes, so that this simplistic picture does not hold during the most interesting times for scientific investigation.

The variety of observational details during disturbed magnetospheric conditions ranges across not only different instrument regimes, but also encompasses time scales ranging from seconds to hours, and spatial scales from meters to nearly global. Consequently the investigation of the environment during disturbed times involves coordinated observations using instruments at widely spaced fixed observatories on the earth, as well as satellite instruments in the solar wind and inside the magnetosphere. At the Antarctic observatories, the signals from many of the instruments are recorded together on a common data logger, and the data are shared among the Principal Investigators (PI's) providing the data, as well as with colleagues operating elsewhere. Since the beginning of the IGY (International Geophysical Year - 1957-1958), the collaboration in Antarctic research has been on an international scale.

The brief discussions presented below are intended to describe the basic objectives of the science experiments involved in studies of solar/magnetospheric/ionospheric coupling processes. More detailed discussions should be sought from the PI's responsible for the science programs.