Milan Bursa Karel Pec Gravity Field and Dynamics of the Earth With 89 Figures Springer-Verlag Berlin Heidelberg New York London Paris Tokyo HongKong Barcelona Budapest
Preface v Introduction 1 1 Fundamentals of Determining the Parameters Defining the Earth's Gravitational Field by Satellite Methods 6 1.1 Introduction 6 1.2 Satellite Equations of Motion 6 1.3 Perturbing Function and Perturbing Potential... 23 1.3.1 General Definitions 23 1.3.2 Perturbing Gravitational Potential of the Earth in Outer Space 24 1.3.3 Perturbations due to the Moon and the Sun 27 1.4 Solution of the Perturbed Motion 28 1.5 Transformation of the Perturbing Gravitational Potential into the Function of the Satellite's Orbital Elements 32 1.5.1 Transformation of Potential R s@ 32 1.5.2 Transformation of Potentials AV S p AV SO 34 1.6 Fundamentals of the Theory of Determining the Parameters of the Earth's Gravitational Potential by Satellite Methods 35 1.6.1 Motion of the Nodal Line due to the Earth's Polar and Equatorial Flattening 35 1.6.2 Geopotential Coefficients Determined from the Variation in Satellite Orbital Elements - An Outline. Numerical Results 38 1.7 The Geocentric Gravitational Constant 42 1.8 Resonance Phenomena 45 1.9 Geostationary Satellites 47 2 The Earth's Gravity Field and Its Sources 51 2.1 Introduction 51 2.2 Gravitational and Gravity Potentials 52
2.3 Transformation of the Gravitational Potential and Potential of Centrifugal Forces Under Rotation of the Coordinate System. Transformation of Geopotential Coefficients 55 2.4 Gravity in Outer Space 57 2.5 Listing's Geoid 62 2.5.1 Monge's Figure of the Geoid 62 2.5.2 Geometrical Properties of the Geoid 63 2.5.3 The Earth's Triaxial Ellipsoid 77 2.5.4 Determination of the Coefficients in the Harmonie Development of the Geoid's Radius-Vector and of the Geopotential Scale Factor R Q 89 2.5.5 Power Series of the Geoid's Radius-Vector 94 2.6 True Gravity Anomalies 97 2.7 Structure of the Gravitational Field over the Northern and Southern Hemispheres 101 2.8 Theory of the Order of Flattening 106 2.8.1 Clairaut's Theory of the External Field 109 2.8.2 Internal Gravitational Field of the Hydrostatic Earth. Clairaut's Differential Equation 112 2.9 Internal Sources of the Gravitational field 117 2.9.1 Physical Interpretation of the Geopotential Coefficients. Tensor of Inertia 118 2.9.2 Transformation of the Coordinate System into the Principal Axes of the Earth's Inertia Tensor 121 2.10 Density Models of the Earth 124 2.10.1 Mean Spherically Symmetrical Models of the Earth 125 2.11 Lateral Density Variations 130 2.11.1 Integral Density Equations 131 2.11.2 Analytical Density Model for a Spherically Asymmetrical Earth 131 2.11.3 Powers x" Developed into a Series of Shifted Legendre Polynomials 132 2.11.4 System of Algebraic Equations for the Density Model Coefficients. Compatibility Conditions for the Mean Spherical Model 133 2.11.4.1 Algebraic Equations for Coefficients FfJ, of the Density Variations Model 133 2.11.4.2 Total Mass of the Earth 135 2.11.5 Moments of Inertia 136 3 Fundamentals of the Earth's Rotation Dynamics... 141 3.1 Introduction 141 3.2 Fundamental Relations of the Earth's Rotation Dynamics, Euler's Dynamic and Kinematic Equations 141
IX 3.3 The Earth's Rotation Dynamics in the Absence of External Moments; Euler's Free Nutation 148 3.4 Liouville's Equations 156 3.5 Polar Motion; Variations in the Angular Velocity of the Earth's Rotation. Numerical Results 162 3.6 Dynamics of the Earth's Rotation and the Problem of Defining Time 178 3.7 Effect of the Deceleration of the Earth's Rotation on the Observed Ephemerides of Orbiting Bodies... 184 3.8 Problem of Realization of the Reference Coordinate System in the Earth's Rotation Dynamics 186 3.9 Fundamentals of the Dynamics of the Earth's Precession and Nutation 189 3.9.1 Force Function of the Earth-Moon-Sun System.. 189 3.9.2 Right-Hand Sides of Euler's Dynamic Equations as Functions of the Gravitational Perturbations due to the Moon and the Sun 198 3.10 Approximate Solution for the Precession-Nutation Motion Under Equal Equatorial Moments of Inertia 202 3.11 Numerical Results 204 4 The Earth's Tides. Tidal Deformation of the Earth's Crust 207 4.1 Introduction 207 4.2 Tide-Generating Potential of a Perfectly Rigid Earth 209 4.3 Tide-Generating Potential of a Perfectly Elastic Earth 220 4.4 Additional Potential in Outer Space due to the Earth's Tidal Deformation 223 4.5 Effect of the Moon's Motion on the Tide-Generating Potential 227 4.6 Components of Tidal Forces 229 4.7 Love Numbers and Methods of Determining Them 237 4.8 The Precession-Nutation Torque of Tidal Forces.. 239 4.9 The Secular Love Number 240 5 The Earth's Deformations and Variations in the Earth's Rotation 245 5.1 Introduction 245 5.2 Dynamics of the Tidal Deceleration of the Earth's Rotation 245 5.3 Deformations of the Earth due to the Variations in tbe Earth's Rotation 259
X Contents 5.3.1 Variations in the Potential of Centrifugal Forces; Perturbing Forces 259 5.3.2 Deformations of Equipotential Surfaces due to Polar Motion for a Perfectly Rigid Earth 267 5.3.3 Deformations of Equipotential Surfaces due to Polar Motion for a Perfectly Elastic Earth 270 5.3.4 Deformations due to Variations in the Earth's Angular Velocity 271 5.3.5 Comparison with Tidal Deformations 273 5.4 Dynamics of the Earth's Ellipsoid of Inertia 274 5.5 On the Hypothesis of an Expanding Earth 277 5.6 Decrease in the Maximum Principal Moment of the Earth's Inertia and Its Effect on Polar Motion... 279 5.7 Secular Decrease in the Earth's Angular Momentum and Kinetic Energy 284 5.8 Long-Term Variations in the Earth's Gravity Field due to Variations in the Earth's Rotation Vector and in the Second Zonal Geopotential Coefficient. 286 6 The Earth in the Solar System 288 6.1 Introduction 288 6.2 Structure of the Solar System 288 6.3 Orbital Elements of the Planets 290 6.4 Laplace's Invariable Plane of the Solar System... 296 6.5 Gravitational Forces Acting on the Earth 302 6.6 Orbital Elements of the Earth and Their Variations in Time 305 Appendix A: Current Representative Values of the Parameters of Common Relevance to Astronomy, Geodesy and Geodynamics 309 References 315 List of the Most Important Symbols 323 Subject Index 329