The Mansurov Effect: A new perspective on the correlation between By and polar pressure

Abstract

<p>The Mansurov effect is related to the interplanetary magnetic field (IMF) and its ability to modulate the global electric circuit, which is further hypothesized to impact the polar troposphere through cloud generation processes. We investigate the connection between IMF By-component and polar surface pressure by using daily ERA5 reanalysis for geopotential height since 1966. Previous studies produce a 27-day cyclic response during solar cycle 23 which appears to be significant according to conventional statistical tests. However, we show here that when statistical tests appropriate for strongly autocorrelated variables are applied, there is a fairly high probability of obtaining the cyclic response and associated correlation merely by chance. Our results also show that data from three other solar cycles, produce similar cyclic responses as during solar cycle 23, but with seemingly random offset in respect to timing of the signal. By generating random normally distributed noise with different levels of temporal autocorrelation, and using the real IMF By-time series as forcing, we show that the methods applied to support the Mansurov hypothesis up to now, are highly susceptible to random chance, as cyclic patterns always arise as artefacts of the methods. Further analyses of the time period 1966-2018 in both polar hemispheres reveals highly significant correlations over large time scales between the 27-day smoothed gradient of the By, Bx and Bz-index, and the geopotential height at 700 hPa. The smoothed gradient can be understood as the movement of the sector structures of the Heliospheric Current Sheet (HCS). As the new results suggest another driver that is only partially related to By, this can explain why the correlations for the raw By is found to be insignificant. The full mechanism of the newly discovered driver is still unknown and under development. <br><br><br><br><br></p>