engleski

THE POSSIBLE IMPACT OF COSMIC RAYS ON EXTRATROPICAL CYCLONE FREQUENCY AND STRENGTH OVER NORTH ATLANTIC

The mechanism based on the global electric circuit (GEC) flowing vertically from the iono- sphere to the Earth’s surface could potentially provide the link between the solar modulated energetic particles and Earth’s weather and climate. Cosmic ray (CR) induced atmospheric ionization modulates the vertical current density (Jz) and introduces the changes in GEC that could alter the microphysical properties of the clouds. Due to the complexity and scale of the GEC and its feedbacks, possible implications and importance of this mechanism are still mostly unknown. One of the possible feedbacks to GEC alteration could be the pro- cess of storm invigoration and occurrence of extratropical cyclones. Using 6-hourly sea level pressure (SLP) fields from the ERA-Interim data, extratropical cyclones are identified by tracking their low-pressure centers. Daily timescale super-positional epoch (composite) anal- ysis is performed to analyze the frequency and strength of cyclones during the short- term reductions in CR flux or so-called Forbush decrease events in the last three solar cycles (1979 - 2015). In order to test the significance of the results the robust Monte Carlo significance testing were employed to avoid the possible false positives that may be obtained with stan- dard statistical tests (e.g. t-test). We don’t find a significant response in the frequency or strength of extratropical cyclones to changes in CR flux during the whole analysis period.

global electric circuit, cosmic rays

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