The Double (Hale) Sunspot Cycle and Floods and Droughts in India

Abstract

H E quest for the possible relationships between sunspots and weatherlclimate T began even before Schwabe, a German astronomer, discovered the sunspot cycle in 1843. In spite of the controversy surrounding the claimed effects of sunspot cycles on weather and climate, consideration is being given to the possible implication for climatological forecasts. In recent years there has been a major revival of interest on the problems of the sun-weathedclimate relationships. New statistical methods and modem computers are being used to tackle hitherto unmanageable calculations in order to test the reality of the effects and put this in proper perspective.It has been argued that there is little or no reliable evidence for significant correlations of either the 11-or 22-year sunspot cycles with variations of weather or climate (Gerety et al. 1977;Pittock 1978). However, among the long-term solar effects, evidence for an approximately 22-year cycle, twice the period of the sunspot cycle, has been found in several climatological variables (Mitchell et al. 1979;Dicke 1979;Hancock and Yarger 1979;Bhalme and Mooley 1980;Weinbeck and Yarger 1981;Williams 1981). The 22-year cycle is supposed to arise as a result of the alternate changes in the polarity of the leading sunspots in a given solar hemisphere in successive 11-year cycles. Thus the true sunspot cycle is 22 years rather than 11 years when the altematioil of sign of spot magnetic fields is considered. The 22-year quasi-cycle of sunspot activity is often termed the double sunspot cycle or Hale sunspot cycle. A recent work by Bhalme and Mooley (1981) provides evidence of an approximately 22-year cycle in the fluctuations of flood area indices over India for the 89-year period 1891-1979, showing strong coherence with the double (Hale) sunspot cycle. Furthermore, they were able to demonstrate the consistent occurrence of large-scale flood events in the major sunspot cycle by harmonic dial analysis. This finding receives support from the study of Ananthakrishnan and Parthasarathy (1983) who found statistically significant excess rainfall years around the peak phase of alternate sunspot cycles.The present note illustrates the association found between the occurrences of large-scale flood events in India and the double (Hale) sunspot cycle by separating drought and Aood years in a single diagram of the sunspot curve and by statistical analysis of the data. METHOD FOR IDENTIFICATION OF DROUGHTS AND FLOODSBhalme and Mooley (1980) developed an objective numerical drought index, based on the monthly monsoon (June-September) rainfall over an area and a duration for assessment of drought intensity. The basic assumption in the development of the index is that plant life and established human activities are geared to the long-term mean monthly rainfall of the area of the specific period and that the deviation from the mean monthly rainfall determines the drought characteristics. The drought index equation is I k = 0.5 Ik-1 + Mk/48.55(1)where Ik, Ik-1 are the drought intensities of the kt...

Rainfall patterns in India

“…However, in the absence of an agreed mechanism to explain fluctuations in the weather in terms of variations in solar activity, the topic fell into disrepute; only in recent times has debate resumed and interest in possible sudweather relationships been renewed. Bhalme and Mooley (1981) and Bhalme and Jadhav (1984a) have found evidence for a c. 22 year cycle of floods and droughts in India, which they associate with the double (Hale) sunspot cycle. Similar findings were reported by Ananthakrishnan and Parthasarathy (1984).…”

“…AND PARTHASARATHY Ananthakrishnan and Parthasarathy (1984) have examined the annual rainfall figures (1871 to 1978) from 306 stations throughout India. As mentioned in the Introduction, these authors report a weak association between Indian rainfalls and the 22 year solar cycle-in good agreement with the earlier findings of Bhalme and Mooley (1981) and Bhalme and Jadhav (1984a). This association was more evident, however, in the initial 54 year period from 1871 to 1924 than in the subsequent period from 1925 to 1978.…”

Climatic impact of El Niño/La Niña on the Indian monsoon: A new perspective

“…For the same reason, India experienced a severe drought during 1899 but Indonesia did not. Bhalme and Jadhav (1984), while examining the association between large-scale flood occurrences over India and the double (Hale) sunspot cycle, have shown that large-scale floods have a tendency to cluster consistently in the positive (major) sunspot cycle. Variation in the annual mean sunspot number suggests that around 1996 it will enter a positive cycle.…”

Time–frequency characterization of sub-divisional scale seasonal rainfall in India using the Hilbert–Huang transform

“…Walker (1933) was perhaps the first to study teleconnections between Indian monsoon rainfall and meteorological parameters at other parts of the earth. Later, several other studies investigated the links of Indian monsoon rainfall with different global climatic oscillations such as QuasiBiennial Oscillation (QBO) (Rao and Lakhole 1978;Vijayakumar and Kulkarni 1995;Claud and Pascal 2007), tidal forcing (Campbell et al 1983), El Nino Southern Oscillation (ENSO) (Shukla and Paolino 1983;Mooley and Parthasarathy 1983;Krishnakumar et al 1999;Gadgil et al 2004), Atlantic Multidecadal Oscillation (AMO) (Goswami et al 2006;Lu et al 2006;Zhang and Delworth 2006;Feng and Hu 2008); Equatorial Indian Ocean Oscillation (EQUINOO) (Gadgil et al 2004;Maity and Nagesh Kumar 2006a;Nagesh Kumar et al 2007), solar indices of sunspot cycle (SN), solar irradiance and sunspot area (Bhalme and Jadhav 1984;Krishnakumar et al 1999;Bhattcharya and Narasimha 2007;Azad 2011) etc. Such investigations helped in finding the potential inputs for rainfall forecasting models and many studies noted that the rainfall time series posses non-linear and non-stationary characteristics Raghukanth 2005, 2006;Maity and Nagesh Kumar 2006b; Nagesh Kumar et al 2007).…”