Comparing effects of various types of Comparing effects of various types of geomagnetic disturbances on the winter lower geomagnetic disturbances on the winter lower

atmosphere in the Northern Hemisphereatmosphere in the Northern HemisphereJosef Bochníček and Pavel Hejda

Geophysical Institute of the Academy of Sciences,141 31 Prague, Czech Republic

e-mail: jboch@ig.cas.czESWW-II, 14 – 18 November 2005, ESA-ESTEC

15-Feb 19-Feb 23-Feb 27-Feb 3-Mar

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Deviations of Geopotential Height17 Feb 1999 - 18 Feb 1999

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Deviations of Geopotential Height24 Feb 1999 - 27 Feb 1999

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ConclusionsProlonged geomagnetic activity as well as isolated strong geomagnetic storms (Ap ≥ 60, Dst < -100 nT) used to be associated with tropospheric pressure and temperature field changes.

6 – 9 days after the onset of the strong geomagnetic storm or the beginning of prolonged geomagnetic activity a decrease of atmospheric pressure in the sector 10° - 40° W and the strengthening of zonal flow over Atlantic and western Europe are observed. Such changes result in advection of relatively warm and moist air.

If the geomagnetic storm or prolonged geomagnetic activity is accompanied by a strong increase of energetic proton flux (Ep > 60MeV), enhanced cyclonic activity in the sector 10° - 40° W, in agreement with Veretenenko & Thejll (JASTP 66/2004, 393-405), follows one day after this increase.

Strong increase of energetic proton flux (Ep > 60 MeV) prolongs duration of tropospheric response on geomagnetic storm about several days.

The effects of isolated geomagnetic storms and prolonged high geomagnetic activity on winter lower atmosphere in the Northern Hemisphere are compared. For this purpose geomagnetic storms with parameters Ap ≥ 60, Dst ≤ -100 nT occurring in the winter periods (January-March) 1994-2002, and geomagnetic activity course in winter period (January-March) 1982 were selected. Pressure, temperature and wind fields between geopotential heights of 1000 mb and 100 mb were investigated. Special attention was paid to analysis of maps of cross-sections along the profile Atlantic-polar region-eastern Asia.

Deviations of Geopotential Height at 500 mb Deviations of Geopotential Height at 500 mb Temperature Deviations at 500 mb Temperature Deviations at 500 mb

Temperature Deviations1 Dec 1981 - 20 Jan 1982

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Temperature Deviations6 Feb 1982 - 8 Mar 1982

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Deviations of Geopotential Height1 Dec 1981 - 20 Jan 1982

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Deviations of Geopotential Height6 Feb 1982 - 8 Mar 1982

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Prolonged high geomagnetic activity – Winter 1981/1982low to medium level of geomagnetic activity in December and January was succeeded by a very high level of

geomagnetic activity in February and the beginning of March

deepening of the Icelandic low warming up in western Europe

Strong isolated stormsFebruary – March 1994

short change of atmospheric circulation after geomag. storm from 6-7 February and prolonged change after

geomag. storm and enhanced Proton Flux from 20-21 Feb.

17-Mar 21-Mar 25-Mar 29-Mar 2-Apr

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Deviations of Geopotential Height28 Mar 2001 - 30 Mar 2001

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Deviations of Geopotential Height1 Apr 2001 - 8 Apr 2001

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Deviations of Geopotential Height10 Apr 2001 - 11 Apr 2001

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March – April 2001low pressure in the sector 10° - 40° W from 28 March to 8 April caused by two consecutive geomagnetic storms and quick return to the initial state after 10 April.

February 2000

February – March 1999deepening of the Icelandic low

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Deviations of Geopotential Height13 Feb 2000 - 13 Feb 2000

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Deviations of Geopotential Height5 Feb 1994 - 6 Feb 1994

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Deviations of Geopotential Height10 Feb 1994 - 12 Feb 1994

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Deviations of Geopotential Height20 Feb 1994 - 21 Feb 1994

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Deviations of Geopotential Height1 Mar 1994 - 15 Mar 1994

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20 Feb 1994 - 21 Feb 1994 1 Mar 1994 - 15 Mar 1994

Deviations of GeopotentialHeights at 500 mb

Wind field at 500 mb

strengthening of zonal flow over Atlantic and western Europe

sectors of the vertical profile

Related papers:

Bochníček, J. and Hejda, P., 2002. Association between extraterrestrial phenomena and weather changes in the Northern Hemisphere in winter. Surveys in Geophys. 23, 303 – 333.

Bochníček, J. and Hejda, P., 2005. The winter NAO pattern changes in association with solar and geomagnetic activity. J. Atmosphere. Solar-Terr. Phys. 67, 17-32.