Lightning atmospherics count rates observed at Halley, Antarctica

Abstract Lightning is considered to be a sensitive indicator of global change in the troposphere. In this paper we report the first results from the lightning atmospherics (sferics) counter deployed as part of the VELOX II experiment at Halley Station, Antarctica (76°S,27°W). We present examples of high-resolution and survey data for the instrument from its deployment in April 1997 up to March 1998. We show that 10 ms time resolution causes saturation effects in the data when the activity level is high. However, we show how a simple simulation algorithm is used both to calibrate the system and to model the observed response to a high level of accuracy. We show evidence of a departure of the distribution of VLF noise amplitudes in the high-resolution time series produced for the model from the lognormal form assumed by many authors and in the design of the present instrument. Comparison is also made with a Rayleigh distribution. We compare the corrected flash rate with lightning power measurements, indicating that previous estimates of long-term changes in sferic power made from Halley are consistent with less than 5% change in flash rate in 25 years.

[1]  Kenneth L. Cummins,et al.  A Combined TOA/MDF Technology Upgrade of the U.S. National Lightning Detection Network , 1998 .

[2]  E. Williams.  The Schumann Resonance: A Global Tropical Thermometer , 1992, Science.

[3]  E. Ney,et al.  Lightning Observations by Satellite , 1971, Nature.

[4]  N. Watkins,et al.  Diurnal and annual variations in 10‐kHz radio noise , 1999 .

[5]  A. Tatnall,et al.  E.l.f./v.l.f. emissions observed on Ariel 4 , 1975, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[6]  D. Turcotte,et al.  Self-Affine Time Series: I. Generation and Analyses , 1999 .

[7]  Keith H. Yearby,et al.  A 25‐year record of 10 kHz sferics noise in Antarctica: Implications for tropical lightning levels , 1998 .

[8]  C. R. Warber,et al.  A long wave transverse electric‐transverse magnetic noise prediction model , 1995 .

[9]  O. Pinto,et al.  Cloud‐to‐ground lightning flash characteristics in southeastern Brazil for the 1992–1993 summer season , 1996 .

[10]  D. Rind,et al.  Possible implications of global climate change on global lightning distributions and frequencies , 1994 .

[11]  Eric W. Weisstein,et al.  The CRC concise encyclopedia of mathematics , 1999 .

[12]  P. J. Jenkins,et al.  A SURVEY OF NATURAL ELECTROMAGNETIC NOISE IN THE FREQUENCY RANGE F= 1-10 KHZ AT HALLEY STATION, ANTARCTICA : 1. RADIO ATMOSPHERICS FROM LIGHTNING , 1998 .

[13]  Andy J. Smith,et al.  VELOX: a new VLF/ELF receiver in Antarctica for the Global Geospace Science mission , 1995 .

[14]  G. Sátori,et al.  El Niňo related meridional oscillation of global lightning activity , 1999 .

[15]  R. Markson.  Tropical convection, ionospheric potentials and global circuit variation , 1986, Nature.

[16]  N. Watkins,et al.  Comparison of VLF sferics intensities at Halley, Antarctica, with tropical lightning and temperature , 2001 .

[17]  H. Volland,et al.  Handbook of atmospheric electrodynamics , 1995 .