Antarctic Atmospheric Electricity and
Ionospheric Convection
Proposal Summary
- Support:
- Not Under Consideration at Present
- Source:
- None. If you are a program director and wish to have it submitted, call (713) 743-3543
or e-mail <eabering@uh.edu>.
- Period:
- 3 years
Abstract
This proposal requests support for the construction and deployment in Antarctica of instruments
that measure the vertical electric field and conduction current in the atmosphere. The questions
that will be studied pertain to global climatic change, atmospheric science and ionospheric
dynamics. The global electric circuit has two principal generators: the electrical activity of the
troposphere and the dynamo interaction of the solar wind with the magnetosphere. In the
troposphere, current is driven from the tops of convective electrified clouds into the Earth's
ionosphere. This current flows from the ionosphere to the Earth's surface through the partially
conducting atmosphere in the non-stormy areas of the Earth. Current in the surface returns to the
active areas where cloud-to-ground lightning, and other currents complete the circuit. By
monitoring the vertical current density at a fair-weather site, the current flowing in the global
electric circuit may be determined. Note that this current is a globally-significant parameter,
because it is directly related to global convective activity and therefore to global warming. The
Antarctic Plateau is the best location on the Earth to measure the atmospheric electric current
density, because it is the highest, driest, flattest area on Earth, the meteorology suppresses
convection, and there are no diurnal influences on local conditions. The global electric circuit
remains ill-measured experimentally. The theory for its behavior is well established; however, the
supporting observations are sparse, largely uncalibrated, and unconvincing without the theoretical
underpinning; most data sets have a 1-hour time resolution. Most low-latitude surface
observations are dominated by local meteorological influences. The proposed research will
directly address these shortcomings by monitoring the global electric circuit at South Pole Station
with high time resolution (1 s), high-quality, digitized measurements made for a long period of
time (decades) to enable us to understand the behavior of the global electric circuit on all
intermediate time scales.The other major objective of this research is to infer the magnetospheric contribution to variations
of the air-earth current as a function of time and position. Model studies have shown that
ionospheric potential variations with scale sizes on the order of 500 km map down to the Earth's
surface. Thus, variations in the air-earth current at the surface are produced by electric fields of
magnetospheric origin. Model calculations, multi-point balloon observations and South Pole data
have indicated that magnetospheric sources can change the air-earth current by > 20% during
periods of geomagnetic quiet and by greater amounts during magnetic storms. Variations of more
than 50 V/m in surface field have been observed during magnetospheric substorms. Deployment
of a network of atmospheric electric detectors will be begun in order to obtain ``snapshots" of the
geomagnetic polar cap potential. The specific objectives of this proposal are:
- Analyze the data that have been acquired at South Pole Station during the period January 1991
to October 1993.
- Evaluate the possible influences of boundary layer dynamics on the atmospheric electrical
measurements.
- Deploy two redesigned atmospheric electric stations at either South Pole or Vostok Stations
adding passive radioactive probes to measure the electric field profile (surface to 3 m).
- In year 2, install detectors at Vostok, South Pole or McMurdo and at one AGO. In year 3, add
instruments at two more AGO's.
- Correlate atmospheric electric perturbations with perturbations in the geomagnetic field owing
to ionospheric currents.