Solar Activity and Earth's Climate

Transcription

1 Rasmus E. Benestad Solar Activity and Earth's Climate Second Edition Published in association with Springer Praxis ids Publishing Publisl PRAXI Chichester, UK

2 Contents Preface to the second edition Preface to the first edition Acknowledgements to the second edition Acknowledgements to the first edition xi xiii xv xvii List of figures xix List of tables xxv 1 Introduction The philosophy of this book The layout 5 2 Solar observations Synopsis Instruments for observing the Sun Measuring the total solar irradiance There is more than total irradiance Spectrography and polarisation The history of solar observations The importance of good observations Criteria for good observations Palaeo records of solar activity Isotopic records Geomagnetic field measurements Space-borne solar observations 25

3 vi Contents 3 The physical properties of the Sun Synopsis The Sun as a star Solar size and mass The solar rotation The solar material The Sun's core The photosphere The chromosphere The corona The solar wind The general solar magnetic field The decay of magnetic fields The geomagnetic-based solar model 41 4 Solar activity Synopsis The umbra The penumbra Sunspot groups Sunspot brightness and temperature Sunspot models Dynamo action and magnetism Convective and hydrodynamical sunspot models Magnetic cooling models Solar activity and preferred timescales Solar activity and the sunspot cycle Spectral analysis Wavelet analysis Comparison between preferred timescales Sunspot groups and their magnetic field Alternative measures of solar activity Observed east-west asymmetry in sunspot statistics The sunspot cycle and total radiance Sunspots and the solar irradiation Sunspot-irradiance models Prediction of sunspots :" Flares, prominences, faculae, and corpuscular clouds Flares Prominences Faculae Corpuscular clouds Solar brightening, sunspots and faculae 87 5 Earth's climate Synopsis 89

4 Contents vii 5.2 The observation of Earth's climate Instrumental data Upper air data Earth-observing satellites and space-borne UV measurements Observation of planetary atmospheres Palaeo data - "proxy data" Climate observations Basic climate physics Mass conservation Energy conservation Ill Momentum conservation Effects of Earth's rotation Charge conservation Earth's energy budget Variations in solar output and terrestrial temperature Variation in insolation The natural greenhouse effect The basic components of Earth's climate The atmosphere The oceans The cryosphere The biosphere Feedback mechanisms Stefan-Boltzmann feedback Water vapour feedback Ice- and snow-albedo feedback Cloud feedback Biochemical feedback The other planets in our solar system The signature of solar variability from other planets Solar activity and the stratosphere Synopsis Solar activity and UV emission The role of stratospheric ozone Chemical reactions The "ozone hole" The theory of a link between solar activity and stratospheric ozone The theory of a link between the QBO and solar activity Introduction Sunspots and the QBO The theory of a link between the AO and solar activity Introduction 159

5 viii Contents A connection between solar activity and the AO Criticism of solar-stratosphere hypotheses Volcanoes Solar magnetism and Earth's climate Synopsis Northern lights and the solar cycle Introduction Earth's magnetic and electric fields Geomagnetic storms The geomagnetic field and solar wind The magnetic field of other planets The Van Allen belts Charging mechanisms Lightning The atmospheric electric field Cosmic rays Interaction between cosmic rays and the air Airglow, sprites and elves A historical note on the aurora: theory and observations Early scientific documentation The aurora and geomagnetic disturbances The discovery of day-side and night-side auroras Charged particles and the aurora The northern lights and the weather The interplanetary magnetic field and the solar cycle The aurora and solar activity The theory of day-side auroras The theory of night-side auroras The aurora and the geomagnetic field Aurora activity Historical climate information from aurora observations Aurora and the Maunder minimum The "Little Ice Age" and aurora activity The magnitude and extent of the "Little Ice Age" The Maunder minimum and the quiet-sun theory, Magnetic fields, cosmic rays and cloud cover The cosmic ray and sulphate hypothesis The electro-freezing hypothesis The galactic cosmic rays and the climate Low and high clouds The hypothesis on cosmic rays and cloud droplet formation Criticism of Svensmark's hypothesis The Maunder minimum 191

6 Contents ix The weakness of comparisons with "Sun-like" stars The influence of corpuscular clouds Solar activity and lightning The geomagnetic field and oceanic currents The geomagnetic field and sea level pressure 196 A review of solar-terrestrial studies Synopsis A brief historical note on solar-terrestrial links Historical account of sunspots and hypothesised links with Earth's climate Recent statistics on solar-terrestrial links A renaissance for solar-terrestrial links Recent work and hypotheses Basic statistical concepts Linear trends Correlation Correlation and de-trending the data Correlation and filtering the data Autocorrelation and lag-correlation Monte Carlo simulations The solar cycle length and terrestrial temperature Considerations on solar cycle lengths Correlation studies and pitfalls Validation of predictions Total solar irradiance studies The "Little Ice Age" and TSI Comparisons with stellar studies The life cycle of a star Inferring the solar evolution from stellar studies The "snowball Earth" effect Is there a relation between sunspots and rainfall? Requirements of solar-terrestrial hypotheses 248 Solar activity and regional climate variations Synopsis El Nino Southern Oscillation and solar activity How solar activity may physically affect ENSO The role of solar activity in the south Asian monsoon system The monsoon Relation to sunspots The North Atlantic Oscillation and sunspots How may the NAO be affected by solar activity? The Gulf Stream and sunspots Pacific Decadal Oscillation and solar activity Land-sea contrasts 273

7 x Contents 9.8 Other external climate forcings The anthropogenic perturbation to the natural balance Orbital parameters The Moon Meteorite impacts Synthesis Appendix 281 Bibliography 285 Exercises 299 Index 309