2002-2003 Science Planning Summary

Aeronomy & Astrophysics

Dr. Vladimir Papitashvili
Program Manager

AO-306-P

NSF/OPP 99-10565
Station: Palmer Station
Research Site(s): Palmer Station

Global thunderstorm activity and its effects on the radiation belts and the lower ionosphere
Dr. Umran S. Inan
Stanford University
Department of Electrical Engineering
inan@nova.stanford.edu
http://www-star.stanford.edu/~vlf/palmer/palmer.htm

Deploying Team Members: Umran S Inan
Research Objectives: Tracking dynamic storms is a challenge, but lightning associated with thunderstorms can provide scientists an indirect way of monitoring global weather. This project employs very-low-frequency (VLF) radio receivers at Palmer Station, operated in collaboration with the British and Brazilian Antarctic Programs, both of which operate similar receivers. All are contributors to the Global Change Initiative.

The VLF receivers measure changes in the amplitude and phase of signals received from several distant VLF transmitters. These changes follow lightning strokes because radio (whistler) waves from the lightning can cause very energetic electrons from the Van Allen radiation belts to precipitate into the upper atmosphere. This particle precipitation then increases ionization in the ionosphere, through which the propagating VLF radio waves must travel. Because the orientations to the VLF transmitters are known, it is possible to triangulate the lightning sources that caused the changes. Once the direction of the lightning source is known, it can be subjected to waveform analysis and used to remotely track the path of thunderstorms.

The data will be correlated with data from the antarctic Automatic Geophysical Observatory network and will be used by scientists studying the magnetosphere and the ionosphere.


Field Season Overview:
The VLF radiometer will continue to operate year-round in the Clean Air/VLF Hut at Palmer Station. One team member will travel to and from Palmer Station on the R/V Laurence M. Gould (cruise LMG 03-04) to upgrade the project's recording equipment. During the rest of the year, the station science technician will maintain and calibrate the equipment, archive the data and send it to the principal investigator.