Svensmark et al. (2009) have recently claimed that strong galactic cosmic ray (GCR) decreases during ‘Forbush Decrease (FD) events’ are followed by decreases in both the global liquid water cloud ...fraction (LCF) and other closely correlated atmospheric parameters. To test the validity of these findings we have concentrated on just one property, the MODIS LCF and examined two aspects: 1) The statistical chance that the decrease observed in the LCF is abnormal. 2) The likelihood of the observed delay (∼5 to 9 days) being physically connected to the FD events. On both counts we conclude that LCF variations are unrelated to FD events: Both the pattern and timing of observed LCF changes are irreconcilable with current theoretical pathways. Additionally, a zonal analysis of LCF variations also offers no support to the claimed relationship, as the observed anomaly is not found to vary latitudinally in conjunction with cosmic ray intensity.
Changes in the galactic cosmic ray (GCR) flux due to variations in solar activity may provide an indirect connection between the Sun's and the Earth's climates. Epoch superpositional (composite) ...analyses of high‐magnitude GCR fluctuations, known as Forbush decrease (FD) events, have been widely used to test this hypothesis, with varied results. This work provides new information regarding the interpretation of this approach, suggesting that FD events do not isolate the impacts of GCR variations from those of solar irradiance changes. On average, irradiance changes of ∼0.4 W m−2 outside the atmosphere occur around 2 days in advance of FD‐associated GCR decreases. Using this 2 day gap to separate the effects of irradiance variations from GCR variations on cloud cover, we demonstrate small, but statistically significant, anomalous cloud changes occurring only over areas of the Antarctic plateau in association with the irradiance changes, which previous workers had attributed to GCR variations. Further analysis of the sample shows that these cloud anomalies occurred primarily during polar darkness, precluding the possibility of a causal link to a direct total solar irradiance effect. This work suggests that previous FD‐based studies may have ineffectively isolated the impacts of GCR variations on the Earth's atmosphere.
Key Points
Composites of Forbush decrease events do not isolate from the effects of TSI
TSI changes correlate to a cloud signal over Antarctica but are not causal
Previous workers incorrectly attributed these anomalies to the effects of GCR
DO WE SEE THE ‘IRON PEAK’? Erlykin, Anatoly D.; Wolfendale, Arnold W.
Acta polytechnica (Prague, Czech Republic : 1992),
12/2013, Letnik:
53, Številka:
A
Journal Article
Cosmic Rays and Cosmology Wibig, Tadeus; Wolfendale, Arnold
Exotic Nuclei and Nuclear/Particle Astrophysics (II) (AIP Conference Proceedings Volume 972),
01/2008, Letnik:
972
Journal Article
Recenzirano
There are two major aspects of the relationship of Cosmic Rays to Cosmology. The first is the problem of the foreground to the cosmic microwave background (CMB), caused by cosmic ray (CR) effects in ...the Galaxy, the CMB being `seen' against this foreground. The second is the relationship of CR to various phenomena in the Cosmos as a whole, specifically, the question of magnetic fields in the Universe and the likely nature of the sources of CR of the highest energy. Both aspects will be considered here.
Evidence for a local 'Single Source' of cosmic rays is amassing by way of the recent precise measurements of various cosmic ray energy spectra from the AMS-02 instrument. To observations of ...individual cosmic ray nuclei, electrons, positrons and antiprotons must now be added the determination of the boron-to-carbon ratio and the energy spectrum of lithium to 2000 GV with high precision. Our analysis leads us to claim that, with certain assumptions about propagation in the Galaxy, the results confirm our arguments regarding the presence of a local single source, perhaps, a supernova remnant (SNR). An attempt is made to determine some of the properties of this SNR and its progenitor star.
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