A critical look at long‐term Sun‐weather relationships

Abstract

Many and varied claims have been made over many years for a relationship between weather or climate and solar variations, notably sunspot cycles. Those relating primarily to the single and double sunspot cycles (of about 11‐ and 22‐year quasi‐periodicities) are critically reviewed in the light of what is known about solar variations, the observed variability of weather and climate, and possible physical connections between the two. Various pitfalls in the application or lack of application of statistics to the problem are discussed and illustrated from the literature. Following a survey of the literature it is concluded that despite the great number of recent papers on the subject, little convincing evidence has yet been produced for real correlations between sunspot cycles and the weather/climate on the 11‐ and 22‐year time scales, although evidence for correlations with solar events on time scales of days appears to exist. The state of the literature in this particularly controversial area must raise doubts as to the prevailing standards of objectivity and critical analysis in other areas of science as well. Clearly, in the case of sun‐weather relationships, further research requires much higher standards of objectivity, with the rigorous and critical application of statistics, and step by step investigation of hypothetical mechanisms. This criticism is not addressed to the recent studies of apparently significant correlations between certain meteorological indices and the passage of interplanetary magnetic sector boundaries; however, the relevance of such correlations to time scales of climatic interest has yet to be demonstrated.

Solar correlates of Southern Hemisphere mid‐latitude climate variability

“…There are perhaps three reasons why Kidson (1925) and Vines (1980) drew conclusions very different from those of the later studies by Nicholls (1981) and Pittock (1978Pittock ( , 1980Pittock ( , 1983, and why, contrary to the latter, the current study found evidence of a sunspot effect on a range of Southern Hemisphere climate parameters.…”

“…However, Nicholls (1981) subsequently tested for a correlation between the sunspot cycle and annual rainfall at 18 stations across Australia, and found few significant correlations (most notably two east-coast tropical sites -Brisbane and Blackall -and Hobart); he concluded these were most likely due to chance alone. Pittock (1978Pittock ( , 1983 examined in considerable detail the hypotheses underpinning a sunspot effect on climate parameters, and revisited many of the data sets purporting to demonstrate a correlation between sunspots and a terrestrial parameter. He concluded, overall, that there was no consistent evidence for any such effect in Australia (and little evidence for such an association anywhere in the world).…”

“…The heavy solid line marks the sunspot cycle. Harris et al (1988) identified days of 'strong' ZWW on the basis of a marked N-S pressure gradient over southeast Australia, with isobars aligned mainly E-W, the presence of one or more cold fronts embedded in the westerly stream, and total duration of the weather system of more than 1 day irradiance associated with the sunspot cycle with terrestrial climate (Pittock, 1978). With regard to the former, the quasi-decadal variability in the southeast Australian ZWW has been persistent; 15 years of data subsequent to the original report confirm that the time series has progressed through another cycle ( Figure 1).…”

Sun–Earth relation: Historical development and present status – A brief review

“…The study of the effects of solar radiation on terrestrial climate has been very copious and has a long history (Pittock, 1978). However, the conclusions have been mostly uncertain and sometimes confusing.…”

Separation of Solar Effects on Ozone from Anthropogenically Produced Trends

“…Rather controversial statistical results (see PITTOCK, 1978) have not yet been explained on a solid physical base. This is even true for the most recent findings on a joint solar cycle-QBO influence on weather patterns (LABITZKE and VAN LOON, 1988).…”