Home -> Ground Based Reseach -> Southern Research Sites -> P2, Antarctica

P2, Antarctica

Latitude/Longitude:
(85.67º S, 313.62º E)

Mag Coordinates:
(-69.93º, Midnight MLT = 3:29 UT)

Instruments    Photos
Publications    AGO Field Manual (PDF)

Main Science

The network of automatic geophysical observatories presents several advantages for observing auroral radio emissions. First, using a network of stations allows the occurrence rate to be measured as a function of latitude and longitude. Second, these remote stations exhibit low background noise levels at HF due to absence of human activities.

Example science results from Antarctic AGO stations:

The absence of man-made interference at the Antarctic AGOs is most noticeable at LF frequencies of 100-500 kHz which are completely obscured by interference at northern latitudes. LF auroral hiss is a broadband radio emission occuring at the onset of auroral substorms. Observations at Antarctic AGOs reveal spectral features of LF auroral hiss never previously documented due to interference. While the peak amplitude of auroral hiss usually occurs at VLF, with the amplitude monotonically decreasing with amplitude at LF, a certain fraction of events peak in the LF band and exhibit a lower frequency cutoff at tens or hundreds of kHz. These are called "LF-cutoff" events. At Antarctic station P1 during 1994-1995, 64 percent of auroral hiss events are the normal type (with maximum amplitude at VLF), 14 percent are ofthe "LF-cutoff" type, and 22 percent are a mixture of both types. Possibly, the "LF-cutoff" feature results from propagation effects. For more details, see LaBelle et al., 1998.

Instrument | Top

LF/MF/HF Receiver

This receiving system consists of a loop antenna of approximately 10 square meters. The antenna response is a dipole, with the null in the horizontal plane oriented such as to null out the largest source of local interference. A low-noise preamplifier at the antenna has frequency response 100 kHz to above 16 MHz, and transmits these signals through a 50-ohm coaxial cable tothe observatory as little as a few hundred feet or as much as a mile away, depending on the station.

The receivers at A-80, A-81, and A-84 measure 150-point spectra over five 3-MHz bands: 1--4 MHz, 4--7 MHz, 7--10 MHz, 10--13 MHz, and 13--16 MHz. The frequency resolution is 20 kHz and the time resolution is approximately 8 s per 150-point spectrum. However, the 3-MHz bands are not measured simultaneously. Rather, the instrument is devoted to each band for five minutes and sequentially samples all the bands, thus requiring 25 minutes to cover all frequencies. Events lasting less than 25 minutes may be captured only over a subset of the total 1-16 MHz frequency range, and very short duration events are observed only if they produce signals in the 3-MHz band being sampled at the time of the event. Within each 3-MHz frequency ranges, these receivers sweep in frequency, sampling lower frequencies first then higher frequencies, and this mode of operation must be considered when interpreting the data, especially when inferring start or end times of impulsive events.

The data are also compressed using a delta-compression algorithm to make optimal use of limited archival space and must be uncompressed in the post-analysis.  In addition to performing this complicated spectral analysis, the receivers at A-80, A-81, and A-84 sample five low- and medium-frequencies (200, 400, 600, 800, and 1000 kHz) once per 8 seconds.

For more information, see the AGO Field Manual (PDF).

Other instruments used at this site include: All Sky Camera, ELF Receiver, Flux-gate Magnetometer, ULF Search-coil Magnetometer, Imaging Riometer, and LF Receiver.

Photos | Top

Photos courtesy of A.T. Weatherwax and Institute for Physical Science and Technology- University of Maryland.

Publications | Top

66. LaBelle, J., Review of recent ground-level observations of terrestrial auroral radio emissions, Planet. Radio Emissions IV, ed. by H.O. Rucker, et al., Austrian Acad. Sci. Press, p. 283, 1997.

69. Hughes, J., and J. LaBelle, The latitude dependence of auroral roar emissions, J. Geophys. Res., 103, 14910, 1998.

70. LaBelle, J., A.T. Weatherwax, M.L. Trimpi, J. Perring, and U.S. Inan, HF auroral hiss observations at high geomagnetic latitudes, J. Geophys. Res., 103, 20459, 1998.

90. LaBelle, J., and R.A. Treumann, Auroral Radio Emissions, 1. Hisses, Roars, and Bursts, to appear in Space Sci. Rev., 2002.

Note: Numbers refer to Full Publication List

Also Note: Most abstracts are freely available through NASA's Astrophysics Data System Bibliographic Services (ADS). Some are available locally.  Full texts are only available to users within institutions that subscribe to the corresponding web-based journal.