The global atmospheric electric circuit– an overview

Michael J. Rycroft1 and Anna Odzimek2

1CAESAR Consultancy, 35 Millington Road, Cambridge CB3 9HW, andCentre for Space, Atmospheric and Oceanic Science,

University of Bath, Bath BA2 7AY, U.K.

2Department of Physics and Astronomy, University of Leicester,University Road, Leicester LE1 7RH, U.K.

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“What the imagination seizes as beauty must be truth”John Keats, poet (1795-1821)

 “Imagination is the highest kite one can fly”

Lauren Bacall, actress (1924-present)

ATMOSPHERIC STUDIES FROM THE INTERNATIONAL SPACE STATION

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SCHEMATIC DIAGRAM OF THE GLOBAL ATMOSPHERIC ELECTRIC CIRCUIT

Ionosphere

Atmosphere

Earth’s land/Ocean surface

Rycroft and Fullekrug, JASTP, 2004, Fig. 1

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Kasemir, 1965

EARLIER ELECTRIC REPRESENTATIONS OF THE GLOBAL ATMOSPHERIC ELECTRIC CIRCUIT

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Markson, 1978

Makino and Ogawa, 1984Nisbet, 1983

Rycroft et al., JASTP, 2000, Fig. 5

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Tinsley and Zhou, JGR, 2006, Fig. 2

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Rycroft, In Fullekrug et al. book, 2006, Fig. 2

DISTRIBUTION OF POTENTIAL AROUND THUNDERCLOUD

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Rycroft et al., JASTP, 2007, Fig. 2

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Rycroft et al., JASTP, 2007, Fig. 12; EGU 2008 poster, Fig. 1

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Rycroft et al., JASTP, 2007, Fig. 15

FAIR WEATHER REGION

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CARNEGIE CURVE AND THUNDERSTORMS

Williams, Global electrical circuit, Encyclopedia of Atm. Sciences, 2002, Fig. 3

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CARNEGIE CURVE AND NUMBER OF LIGHTNING FLASHES (OTD DETECTOR)

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Nickolaenko et al., GRL, 2006, Fig. 4

Williams et al., JGR, 2006, Fig. 2

DIAGRAMMATIC LIGHTNING DISCHARGES (IN RED)

Altitude [ km ]

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Rycroft et al., JASTP, 2007, Fig. 13

-CG PRODUCING STORM

+CG PRODUCING STORM

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Odzimek and Rycroft, EGU 2008 poster, Fig. 2

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IONOSPHERIC POTENTIAL AFTER LIGHTNING DISCHARGES

SPACE-TIME REGIONS AFTER CG DISCHARGE WHERE BREAKDOWN FIELDS EXCEEDED

Odzimek and Rycroft, EGU 2008 poster, Fig. 3

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Odzimek and Rycroft, EGU 2008 poster, Fig. 4

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Odzimek and Rycroft, EGU 2008 poster, Fig. 5

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CONCLUSIONS

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We must strive to understand better all aspects of the Earth’s atmosphere, and how it responds to both external and internal influences (feedbacks).

An electrical engineering - software - model of the DC global atmospheric electric circuit, with 1 km vertical resolution, has been constructed; it uses a realistic model of the height profile of atmospheric electrical conductivity.

The currents generated by thunderstorms and electrified shower clouds contribute about equally (~ 500 A each) to maintaining the positive potential (~ 250 kV) of the ionosphere with respect to Earth (both good conductors).

Lightning does not contribute very significantly (i.e. only ~1%) to maintaining the high potential of the ionosphere, because the effects of + and – cloud-to-ground (CG) discharges essentially cancel each other out.

+CGs with significant continuing currents can lead to “carrot” sprites, whereas +CGs with only a return stroke can lead to “column “ sprites.

The increased conductivity of the mesosphere (10-7 S/m) associated with a sprite decreases the ionospheric potential by only ~1 V more than for a +CG which is not followed by a sprite.

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THANK YOU – ANY QUESTIONS?

E-mail: michaelrycroft@btinternet.comao64@ion.le.ac.uk

News on 7 May 2008:

Hot night in Chile: dust and ash from the eruption of the Chaitén volcano explodes into the night sky as an electric storm passes overhead(News, page 27)

Photo from http://www.timesonline.co.uk