TY - JOUR
T1 - New model simulations of the global atmospheric electric circuit driven by thunderstorms and electrified shower clouds
T2 - The roles of lightning and sprites
AU - Rycroft, Michael J.
AU - Odzimek, Anna
AU - Arnold, Neil F.
AU - Füllekrug, Martin
AU - Kułak, Andrzej
AU - Neubert, Torsten
N1 - Funding Information:
A part of this research ( Sections 1–4 ) was sponsored by the European Commission under contract CAL HPRN-CT-2002-00216. The authors are also most grateful to the two referees for their helpful and insightful comments, which led to the studies described in Sections 5–7 .
PY - 2007/12
Y1 - 2007/12
N2 - Several processes acting below, in and above thunderstorms and in electrified shower clouds drive upward currents which close through the global atmospheric electric circuit. These are all simulated in a novel way using the software package PSpice. A moderate negative cloud-to-ground lightning discharge from the base of a thunderstorm increases the ionospheric potential above the thundercloud by 0.0013%. Assuming the ionosphere to be an equipotential surface, this discharge increases the current flowing in the global circuit and the fair-weather electric field also by 0.0013%. A moderate positive cloud-to-ground lightning discharge from the bottom of a thunderstorm decreases the ionospheric potential by 0.014%. Such a discharge may trigger a sprite, causing the ionospheric potential to decrease by ∼ 1 V. The time scales for the recovery of the ionospheric potential are shown to be ∼ 250 s, which is of the same order as the CR time constant for the global circuit. Knowing the global average rate of lightning discharges, it is found that negative cloud-to-ground discharges increase the ionospheric potential by only ∼ 4 %, and that positive cloud-to-ground discharges reduce it by ∼ 3 %. Thus, overall, lightning contributes only ∼ 1 %-an almost insignificant proportion-to maintaining the high potential of the ionosphere. It is concluded that the net upward current to the ionosphere due to lightning is only ∼ 20 A. Further, it is concluded that conduction and convection currents associated with "batteries" within thunderclouds and electrified shower clouds contribute essentially equally (∼ 500 A each) to maintaining the ionospheric potential.
AB - Several processes acting below, in and above thunderstorms and in electrified shower clouds drive upward currents which close through the global atmospheric electric circuit. These are all simulated in a novel way using the software package PSpice. A moderate negative cloud-to-ground lightning discharge from the base of a thunderstorm increases the ionospheric potential above the thundercloud by 0.0013%. Assuming the ionosphere to be an equipotential surface, this discharge increases the current flowing in the global circuit and the fair-weather electric field also by 0.0013%. A moderate positive cloud-to-ground lightning discharge from the bottom of a thunderstorm decreases the ionospheric potential by 0.014%. Such a discharge may trigger a sprite, causing the ionospheric potential to decrease by ∼ 1 V. The time scales for the recovery of the ionospheric potential are shown to be ∼ 250 s, which is of the same order as the CR time constant for the global circuit. Knowing the global average rate of lightning discharges, it is found that negative cloud-to-ground discharges increase the ionospheric potential by only ∼ 4 %, and that positive cloud-to-ground discharges reduce it by ∼ 3 %. Thus, overall, lightning contributes only ∼ 1 %-an almost insignificant proportion-to maintaining the high potential of the ionosphere. It is concluded that the net upward current to the ionosphere due to lightning is only ∼ 20 A. Further, it is concluded that conduction and convection currents associated with "batteries" within thunderclouds and electrified shower clouds contribute essentially equally (∼ 500 A each) to maintaining the ionospheric potential.
KW - Global atmospheric electric circuit
KW - Lightning
KW - Simulation
KW - Sprites
UR - http://www.scopus.com/inward/record.url?scp=36148973203&partnerID=8YFLogxK
U2 - 10.1016/j.jastp.2007.09.004
DO - 10.1016/j.jastp.2007.09.004
M3 - Article
AN - SCOPUS:36148973203
SN - 1364-6826
VL - 69
SP - 2485
EP - 2509
JO - Journal of Atmospheric and Solar-Terrestrial Physics
JF - Journal of Atmospheric and Solar-Terrestrial Physics
IS - 17-18
ER -