Could this be why climate models do rainfall with all the competence of tea-leaf-reading? Tiwari et al report that as much as 47% of the recharge rates of ground water in China are controlled by the sun. Apparently climate models miss the minor factor of the major cycles.
Try this radical idea on: imagine a world where climate models worked. Not only could the BoM warn people that there would be a drought coming, they could name the region, and the years.
Tiwari et al:
Here for the purpose of comparison of long term ground water recharge rates with long term solar activity, we used the 10-year average sunspot time series, for the period 1300 to 1905 AD, published by Solanki et al., . Also the additional average annual sunspot number time series (1700 to 2000 AD) is used from data source Solar Influences Data Analysis Centre. In addition to decadal data annual sunspot number data from 1700 to 2000 AD downloaded from Solar Influences Data Analysis Centre is used in the present study. The cross-correlation coefficient (+0.63) between the groundwater recharge rate time series and decadal sunspot number [Solanki et al., 2004] shows that there is statistically significant solar forcing on ground water recharge. Fig.3 shows the comparison of long-term averaged ground water recharge rates data with long term sunspot cycles.
Multiple spectral and statistical analyses of a 700-year long temporal record of groundwater recharge from the dry lands, Badain Jaran Desert (Inner Mongolia) of North West China reveal a stationary harmonic cycle at ~200± 20 year. Interestingly, the underlying periodicity in groundwater recharge fluctuations is similar to those of solar induced climate cycle “Suess wiggles” and appears to be coherent with phases of the climate fluctuations and solar cycles. Matching periodicity of groundwater recharge rates and solar and climate cycles renders a strong impression that solar induced climate signals may act as a critical amplifier for driving the underlying hydrographic cycle through the common coupling of long-term Sun-climate groundwater linkages.
Tawari et al use 10 year smoothed TSI and talk about long term peaks (the ones that occur every couple of hundred years). Obviously the mechanism is unclear and open to speculation:
One can apparently see, however, that the wet seasons are well correlated with the high sunspot number periods, which establish reduced total solar irradiance from the Sun. It indicates that the ground water recharge rates are some way or other linked to the long term solar activity. The decrease in the solar illumination by means of sunspot reduces the Total Solar Irradiance (TSI), where as the reversal phase of sunspot increases the TSI through Facular excess emission [Frohlich, 2000]. Increase in the temperature cause changes in timing and intensity of precipitation, which might affect the ground water recharge rates. It may be suggested that probable mechanism through which the Sunspot number may affect the ground water recharge perhaps could be via increase in the temperature at times of solar minimum, which would in turn enhance the evaporation of the water from the surface resources leading to reducing infiltration and thereby would significantly trim-down/modify the long term ground water recharge. Our analysis demonstrates a ~200 ± 20 year stationary and statistically significant periodicity in which dry period phases appears to synchronize with the solar minima’s. The study also indicates that the 47.5% of the groundwater recharge possibly modified by the solar-climate induced activities. The coupling process of groundwater variability with solar activity and climate on long time scales may be useful for constraining the model and criteria for future prediction and monitoring ground water recharge fluctuations with underlying time constant.
h/t to the HockeySchtick
R.K. Tiwari1,* and Rekapalli Rajesh2 (2014) Imprint of long-term solar signal in groundwater recharge fluctuation rates from North West China. Geophysical Research Letters, DOI: 10.1002/2014GL060204