The Current Solar Minimum and Its Consequences for Climate

Transcription

1 Chapter 11 The Current Solar and Its Consequences for Climate David Archibald Summa Development Limited Chapter Outline 1. Introduction The Current Summary INTRODUCTION A number of cycles in solar activity have been recognized, including the Schwabe (11 years), Hale (22 years), Gleissberg (88 years), de Vries (21 years), and Bond (1,47 years) cycles. There is nothing to suggest that cyclic behavior in solar activity has ceased for any reason. Therefore, predicting when the next minimum should occur should be as simple as counting forward from the last one. The last major minimum, the Dalton from 1798 to 1822, was two solar cycles long e Solar Cycles 5 and 6. Recent Gleissberg minima appear to be the decade 169e17, Solar Cycle 13 from 1889 to 191, and Solar Cycle 2 from 1964 to A de Vries cycle event, herein termed the Eddy, has started exactly 21 years after the start of the Dalton. Friis-Christensen and Lassen theory, using methodology pioneered by Butler and Johhnson at Armagh, can be used to predict the temperature response to the Eddy for individual climate stations with a high degree of confidence. The latitude of the US-Canadian border is expected to lose a month from its growing season with the potential for un-seasonal frosts to further reduce agricultural productivity. Evidence-Based Climate Science. DOI: 1.116/B Copyright Ó 211 Elsevier Inc. All rights reserved. 277

2 278 PART j IV Solar Activity 2. THE CURRENT MINIMUM As recently as 28, there was a wide range in estimated amplitudes for Solar Cycle 24, from Dikpati at 19 and Hathaway at 17 respectively to Clilverd (25) at 42 and Badalyan et al. (21) at 5. This enormous divergence in projections of solar activity generated very little interest from the climate science community, despite the large impact it would have on climate (Archibald, 26, 27). The basis of Clilverd s prediction was a model for sunspot number using low-frequency solar oscillations, with periods of 22, 53, 88, 16, 213, and 42 years modulating the 11-year Schwabe cycle. The model predicts a period of quiet solar activity lasting until approximately 23 followed by a recovery during the middle of the century to more typical solar activity cycles with peak sunspot numbers around 12. The graphs in Figs. 1e15 show data related to solar activity. Additional data may be found in Archibald (21). The Eddy (Fig. 1) has started 21 years after the start of the Dalton, consistent with it being a de Vries Cycle event. The graph in Fig. 2 shows that Solar Cycles 3 and 4, leading up to the Dalton, are very similar in amplitude and morphology to Solar Cycles 22 and 23, leading up to the current minimum. The two data sets are aligned on the month of transition between Solar Cycles 4 and 5 and between Solar Cycles 23 and 24. In the absence of a significant change in Total Solar Irradiance over the solar cycle, modulation of the Earth s climate by the changing flux in galactic cosmic Dalton Projected Eddy FIGURE 1 Solar cycle amplitude 171e245.

3 Chapter j 11 The Current Solar Solar Cycle 3 Solar Cycle 22 Solar Cycle 4 Solar Cycle 23 compared to Solar Cycle 4 Aligned on month of minimum Solar Cycle Amplitude Solar Cycle 23 May 21 Dalton Solar Cycle 5 Solar Cycle FIGURE 2 Similarity between precursor cycles Sporer Maunder Dalton Decreasing Galactic Cosmic Rays Little Ice Age Modern Warm Period FIGURE 3 Be 1 from the Dye 3 ice core, Greenland Plateau. rays was proposed by Svensmark and Friis-Christensen (1997). The Dye 3 Be 1 record (Fig.3) shows a correlation between spikes in Be 1 and cold periods for the last 6 years. It also shows a steep decline in Be 1 in the Modern Warm Period, suggesting a solar origin for this warming. Usokin et al. (25) found

4 28 PART j IV Solar Activity s cooling period Interplanetary Magnetic Field smoothed 27 day average 8 nanoteslas Solar Cycle 2 Solar Cycle 21 Solar Cycle 22 Solar Cycle FIGURE 4 Interplanetary Magnetic Field 1966e Solar Cycle 23 Solar Flux Units s Cooling Period Projection 5 F1.7 Flux FIGURE 5 F1.7 flux 1948e22. that the level of solar activity during the past 7 years is exceptional, and the previous period of equally high activity occurred more than 8, years ago. The strength of the Interplanetary Magnetic Field (Fig. 4) has fallen to levels below that of previous solar cycle transitions. What is also interesting in

5 Chapter j 11 The Current Solar aa Index s Cooling Period Increasing Solar Activity 5 Little Ice Age Modern Warm Period FIGURE 6 The aa Index 1868e21. Monthly Average Counts per Minute Oulu Neutron Count s Cooling Period 21/22 Solar 22/23 Solar 23/24 Solar Data: Sodankyla Geophysical Observatory FIGURE 7 Oulu, Finland neutron monitor count 196e21. this data is the flatness of this solar magnetic indicator during the 197s cooling period. The F1.7 index (Fig. 5) is a measure of the solar radio flux near the peak of the observed solar radio emission. Emission from the Sun at radio wavelengths

6 282 PART j IV Solar Activity FIGURE 8 The correlation between solar cycle length and mean annual temperature at Armagh, Northern Ireland. 1.6 Degrees Celsius Archangel, Russia rsq =.38 Correlation =.6 degrees/annum FIGURE 9 Solar Cycle Length Years Archangel, Russia e solar cycle length relative to average annual temperature.

7 Chapter j 11 The Current Solar Providence, Rhode Island rsq =.38 Degrees Celsius Correlation =.62 degrees/annum Solar Cycle Length Years FIGURE 1 Providence, Rhode Island e solar cycle length relative to average annual temperature Hanover, New Hampshire rsq =.53 Degrees Celsius Correlation =.73 degrees/annum Solar Cycle Length Years FIGURE 11 Hanover, New Hampshire e solar cycle length relative to average annual temperature.

8 284 PART j IV Solar Activity West Chester, Pennsylvania rsq =.29 Degree Celsius Correlation =.5 degrees/annum Solar Cycle Length Years FIGURE 12 West Chester, Pennsylvania e solar cycle length relative to average annual temperature Portland, Maine rsq = Degree Celsius Correlation =.7 degrees/annum Solar Cycle Length Years FIGURE 13 Portland, Maine e solar cycle length relative to average annual temperature. is due primarily to diffuse, non-radiative heating of coronal plasma trapped in the magnetic fields overlying active regions. It is the best indicator of overall solar activity levels and is not subject to observer bias in the way that the counting of sunspots is. The graph above shows the F1.7 flux from 1948 with

9 Chapter j 11 The Current Solar Solar Cycle Amplitude S.C. 24 S.C. 25 Eddy FIGURE 14 The ability to look forward using a model of solar activity. 4 3 Parana River Streamflow 2 1 Sunspot Number FIGURE 15 The correlation between the de-trended time series for the Parana River stream flow and sunspot number. a projection to 22. Note the lower activity of the 197s cooling period. Activity over the next 1 years is projected to be much lower again. The aa Index (Fig. 6) is a geomagnetic activity index which is driven by the solar coronal magnetic field strength. The strength of the solar coronal magnetic field doubled over the 2 th century. At the same time, the Earth came

10 286 PART j IV Solar Activity out of the Little Ice Age. There was a dip in the aa Index associated with the 197s cooling period. The aa Index has now fallen back to levels last seen in the Little Ice Age in the late 19 th century. A weaker Interplanetary Magnetic Field results in more galactic cosmic rays reaching the inner planets of the solar system, seen in Fig. 7 of the neutron count of the Oulu station in Finland. The peak neutron count can be more than a year later than the month of solar minimum. This is due to the time the solar wind takes to reach the heliopause, which is the boundary of the solar atmosphere with interstellar space. Note the much higher average neutron count during the 197s cooling period associated with Solar Cycle 2. The increased galactic cosmic ray flux expected over Solar Cycle 24 will cause increased cloudiness, which will in turn increase the Earth s albedo, and the world will then cool in search of a new equilibrium temperature. Friis-Christensen and Lassen (1991) demonstrated that global temperature over a solar cycle is better correlated with the length of the previous solar cycle than with solar cycle amplitude. In 1996, Butler and Johnson at the Armagh Observatory applied that theory to the temperature record of the observatory and produced the graph shown in Fig. 8. This graph can be considered as the Rosetta Stone of solareclimate studies; in that it has significant predictive power. Simply, Solar Cycle 22 was 9.6 years long, equating to a temperature of about 9.6 C at Armagh. Solar Cycle 23 was 12.5 years long, equating to a temperature of 8.2 C at Armagh. The difference is 1.4 C which is the temperature fall, on average, predicted over Solar Cycle 24. There is not much scatter on this graph and therefore this result is almost certain. A number of European temperature records show a correlation between solar cycle length and temperature, including the Central England Temperature record and de Bilt in the Netherlands. Generally, the more northerly the location, the better the correlation. The graph in Fig. 9 shows the correlation for Archangel in Russia. Providence, Rhode Island will be 1.8 C colder over Solar Cycle 24 relative to its average temperature over Solar Cycle 23 (Fig. 1). Hanover, New Hampshire will be 2.2 C colder over Solar Cycle 24 relative to its average temperature over Solar Cycle 23 (Fig. 11). West Chester, Pennsylvania will be 1.5 C colder over Solar Cycle 24 relative to its average temperature over Solar Cycle 23 (Fig. 12). Portland, Maine will be 2.1 C colder over Solar Cycle 24 relative to its average temperature over Solar Cycle 23 (Fig. 13). The graph in Fig. 14 is from a model provided by Ed Fix (this volume). The notion that the orbits of the planets, particularly Jupiter, are responsible for generating the sunspot cycle has been with us since the discovery of the sunspot cycle by Samuel Schwabe in The model is based on changes in the Sun s orbit about the barycenter of the solar system as the driver of the sunspot cycle. It is a simple oscillatory model driven by the acceleration of the radial component of the barycenter s position relative to the Sun. The model has

11 Chapter j 11 The Current Solar 287 a very good hindcast match. At face value, it is predicting two very short and weak cycles. What is more likely is that there will be phase destruction over Solar Cycle 24, including the possibility that the solar magnetic poles will not reverse at solar maximum, predicted by other methods to be in 215. The Parana River, in central South America, runs through Brazil, Paraguay, and Argentina for nearly 4, km and is the second largest river in South America after the Amazon. Its outlet is the River Plata a few kilometers north of Buenos Aires. In 21, three Argentinean researchers, Pablo Mauas, Andrea Buccino, and Eduardo Flamenco, published a paper showing the very strong correlation between sunspot activity and stream flow of the Parana River (Fig. 15). The relationship demonstrated has predictive power, and points to future drought conditions in the Amazon region as a consequence of the weak activity of Solar Cycle SUMMARY The world has entered a de Vries cycle event in solar activity which will produce a decline in temperature in the range of 1.2e2.2 C in the mid-latitude regions, with a consequent impact on agricultural productivity. REFERENCES Archibald, D., 26. Solar cycles 24 and 25 and predicted climate response: Energy and Environment 17, 29e38. Archibald, D., 27. Climate outlook to 23: Energy and Environment 18, 615e619. Archibald, D., 21. The Past and Future of Climate. Rhaetian Management Pty Ltd, p Badalyan, O.G., Obridko, V.N., Sykora, J., 21. Brightness of the coronal green line and prediction for activity cycles 23 and 24: Solar Physics 199, 421e435. Butler, C.J., Johnston, D.J., A provisional long mean air temperature series for Armagh Observatory. Journal of Atmospheric and Terrestrial Physics 58, 1657e1672. Clilverd, M., 25. Prediction of solar activity the next 1 years. Solar Activity: Exploration, Understanding and Prediction, Workshop in Lund, Sweden. Friis-Christensen, E., Lassen, K., Length of the solar cycle: an indicator of solar activity closely associated with climate: Science 254, 698e7. Solheim, E., 21. Solen varsler et kaldere tiar: Astronomi 4/1, 4e6. Svensmark, H., Friis-Christensen, E., Variation in cosmic ray flux and global cloud coverageda missing link in solar-climate relationships: Journal of Atmospheric and Solar Terrestrial Physics 59, Usokin, I.G., Schuessler, M., Solanki, S.K., Mursula, K., 25. Solar activity, cosmic rays, and the Earth s temperature: a millennium-scale comparison. Journal of Geophysical Research 11, A112.