Forbush decreases – clouds relation in the neutron monitor era

Abstract

The proposed influence of cosmic rays on cloud formation is tested for the effect of sudden intensity changes of CR (Forbush decreases) on cloudiness. An attempt is made to widen the investigated period covered by satellite observation of cloudiness. As an indicator of cloud cover, the diurnal temperature range (DTR - a quantity anticorrelated with cloudiness) is used. The superposed epoch analysis on a set of isolated Forbush decreases is conducted and the results for a region of Europe are presented. The effect of Forbush decrease on DTR is statistically significant only if the analysis is restricted to high amplitude FDs (above the threshold value of 7% with the respect to undisturbed CR intensity). The magnitude of the effect on DTR is estimated to be (0.38 ± 0.06) °C

The response of clouds and aerosols to cosmic ray decreases

“…Kristjánsson et al [] and Todd and Kniveton [] found some response in cloud satellite data, while Pudovkin and Veretenenko [], Harrison and Stephenson [], and Harrison and Ambaum [] found a response based on surface observations. A signal in middle‐ and high‐level clouds has been reported by Rohs et al [], and Dragić et al [] found a signal by using the diurnal temperature range as a cloud proxy, which allowed them to extend the data range farther back than the onset of satellite measurements.…”

Cosmic rays muon flux measurements at Belgrade shallow underground laboratory

“…Onehour time series of the cosmic ray muon intensity at the ground level are checked for correlation with European neutron monitors ( NM ), with emphasis on occasional extreme solar events, e.g. Forbush decreases (FD ) in order to investigate claims of influence of cosmic-rays on cloud formation and climate [8,9] In some specific time periods, like during the FD in March 2012, we showed that our muon measurement system has sensitivity comparable to European neutron monitors in this period, but still not as efficient as NM with better geographical position (at high altitude), e.g. Jungfraujoch in the Swiss Alps.These results are presented at Fig.…”

Does the diurnal temperature range respond to changes in the cosmic ray flux?

“…For consistency, we have used the same 189 European region meteorological stations as listed in the on-line supplementary material of Dragić et al (2011). An example of the daily values of DTR from Dnipropetrovśk station (Ukraine), is shown in figure 1(a).…”

“…It has been proposed by Dragić et al (2011Dragić et al ( , 2013) that a long-debated link between solar activity and terrestrial cloud properties may be reliably detected by applying composite analysis techniques to observations of the diurnal temperature range (DTR-a quantity defined as the difference between observed daily minimum and maximum surface air temperatures). Dai et al (1999) have shown that the DTR can be used as a proxy for cloud cover, and so detections of significant DTR changes corresponding to solar variability (e.g.…”

“…The composite methods and Monte Carlo (MC) analysis approaches employed throughout this work are described in detail in Laken andČalogović (2013). Dragić et al (2011) reported that significant reductions in the DTR have been observed over Europe following the most intense Forbush decrease (Fd) events, these are sudden daily timescale reductions in the background CR flux (Forbush 1937, Cane 2000. Furthermore, recent work by Dragić et al (2013) suggest that the inverse conditions, ground level enhancement (GLE) events (a high-magnitude increase in the CR flux (Meyer et al 1956)), produce increases in the DTR.…”