The Diurnal Temperature Range for Europe: A Search for Cosmic Ray Forbush Decrease Manifestations and the DTR Periodicities

Following on previous work by others, which gave evidence for few days’ changes in the European Diurnal Temperature Range (DTR) apparently correlated with Cosmic Ray Forbush Decreases, we have made an independent study. We find no positive evidence. An analysis has also been made of the Fourier components of the time series of the DTR value (taken as deviations from a ±10 day running mean). Evidence for a number of interesting periods is found, including one at about 27 days, albeit with a variability with time. The same period of solar irradiance (particularly in the UV) is favoured as the explanation. 1. Introduction Uncertainty relating to the relevance of Cosmic Rays (CR) to climate change continues. Although some work (our own included—e.g., Erlykin et al. [1–3]) has cast doubts on the claims of Svensmark and Friis-Christensen [4] and others that there is a causal correlation of Low Cloud Cover (LCC, altitude <3.2？km, i.e., the “boundary layer”) with CR intensity, doubts remain. The supporters draw attention to the results from the CLOUD project [5] which give evidence for an effect of accelerator particles on nucleation rates. The supporters also draw attention to the Diurnal Temperature Range (DTR) data from European stations where there is an apparent correlation with Forbush Decreases (FD) according to Dragic et al. [6]. The work just referred to is in the spirit of studies by Lu and Sanche [7], and others, which claimed evidence for CR having an effect on Atmospheric Chlorofluorcarbon Dissociation and Ozone depletion in the Polar atmosphere. It is with the DTR work that we are concerned here. Although the DTR, which is the day-night temperature difference, is affected by a number of atmospheric parameters (cloud cover, precipitation, changes in agriculture, water vapour feedback, etc.) it is an important quantity to study for two reasons. (i)It can be measured in a straightforward way. (ii)It decreased on a global scale from the 1950s onwards, at the time when the mean Global temperature started to increase markedly (Global Warming). DTR has in it therefore a number of (often dependent) climate parameters and these could be, in principle, CR dependent (see [8] for details of DTR for Europe for the range 1950–2005). FD analyses are useful in that for the short time spans involved (days) phenomena other than CR might be expected to change only slowly so that CR effects dominate. 2. Previous FD Studies Searches for the correlation of FD with other atmospheric parameters have already been made. Specifically, Svensmark et al. [9] searched for, and