Premium
Twentieth century secular decrease in the atmospheric potential gradient
Author(s) -
Harrison Giles
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2002gl014878
Subject(s) - atmospheric sciences , lightning (connector) , environmental science , thunderstorm , ionosphere , atmospheric electricity , climatology , potential gradient , meteorology , physics , geology , electric field , geophysics , power (physics) , quantum mechanics
Current flowing in the global atmospheric electrical circuit (AEC) substantially decreased during the twentieth century. Fair‐weather potential gradient (PG) observations in Scotland and Shetland show a previously unreported annual decline from 1920 to 1980, when the measurements ceased. A 25% reduction in PG occurred in Scotland 1920–50, with the maximum decline during the winter months. This is quantitatively explained by a decrease in cosmic rays (CR) increasing the thunderstorm‐electrosphere coupling resistance, reducing the ionospheric potential V I . Independent measurements of V I also suggest a reduction of 27% from 1920–50. The secular decrease will influence fair weather atmospheric electrical parameters, including ion concentrations and aerosol electrification. Between 1920–50, the PG showed a negative correlation with global temperature, despite the positive correlation found recently between surface temperature and V I . The 1980s stabilisation in V I may arise from compensation of the continuing CR‐induced decline by increases in global temperature and convective electrification.