Analysis of Global Atmospheric Responses to Externally and Internally Driven Global Circuit Variability

University Of Texas At Dallas, Richardson TX

Investigators

Abstract

Previous funded research has shown that the strength of winter cyclones in the Northern Hemisphere varies with changes in the current flow (Jz) in the global atmospheric electric circuit, driven by several independent external generators due to the solar wind. The external drivers are changes in cosmic ray flux, reductions in precipitating relativistic electron flux at solar wind magnetic sector boundary crossings, (now called heliospheric current sheet, or HCS crossings, that are associated with periods of several days of low solar wind speed); and solar proton events. The research also showed that surface pressure in both the Antarctic and Arctic responds to the solar wind electric field that penetrates into the polar caps. The pressure responses are opposite in the two polar caps, following the opposite Jz responses to the solar wind electric field in each polar cap. Another result was that the surface pressures in 7 Arctic stations and 11 Antarctic stations show responses at the level of a few hPa to the day-to-day changes in the internal generators of the global circuit (low latitude, highly electrified convective cloud). The observational results are consistent with a conceptual model in which Jz deposits positive charge in the conductivity gradients associated with droplet concentration gradients at the tops of layer clouds, and deposits negative charge similarly at the bases of such clouds, in accordance with Gauss's Law. This charge attaches to droplets and aerosol particles, including cloud condensation nuclei (CCN) and ice forming nuclei (IFN) and affects the rate at which these and other aerosol particles are scavenged by cloud droplets, and can lead to changes in cloud cover, precipitation, and the atmospheric radiation balance. This project will extend the research to the southern hemisphere by examining meteorological data for the southern hemisphere to test for cyclone variability related to Jz changes. Observations of the solar wind speeds will be examined for decreases in the speed which will indicate changes induced by relativistic electron precipitation, as suggested by the conceptual model, rather than heliospheric current sheet crossings, to improve the understanding of these links. Another component is to re-examine the meteorological responses to Forbush decreases of the galactic cosmic ray flux, using 20 years of more recent data. The conceptual model will be used to predict the vorticity of winter storms due to internally generated changes in Jz, as well as the responses of cloud cover and precipitation changes. None of these changes in atmospheric dynamics induced by electric charge in layer clouds are currently included in global forecast or climate models. As a result of this project, day-to-day forecasts of winter storm strength may be improved, based on forecasts of thunderstorm activity in the main generating regions, and forecasts of space weather, that affect Jz.