Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #1 1-Nov-15 Swarm End-To-End Mission Performance Study Final Presentation The Swarm E2E Consortium DSRI: Eigil Friis Christensen Flemming Hansen Alexei Kuvshinov Nils Olsen Per Lundahl Thomsen Susanne Vennerstrøm IPGP: Gauthier Hulot Mioara Mandea BGS: Vincent Lesur Susan Macmillan Alan Thomson GFZ: Monika Korte Hermann Lühr Stefan Maus Christoph Reigber Patricia Ritter Martin Rother GSFC: Michael Purucker Terence Sabaka IUEM: Pascal Tarits

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #2 1-Nov-15 Outline of Presentations Overview, Achieved Milestones (NIO) Results: Comprehensive Inversion (TJS) Results: Lithospheric Field Recovery Using Gradient Method (HL) Results: Mapping of 3D Mantle Inhomogeneities (NIO) Assessment (NIO) General discussion

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #3 1-Nov-15 Study Logic Task 1: Industrial Module –to be used by industry for their system simulation –Output: software (Matlab) + documentation Task 2+3: Swarm mission simulation –Determination and evaluation of scientific benefit of different mission scenarios –Task 3: including s/c and payload errors (from models provided by industry)

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #4 1-Nov-15 The Magnetic Field Contributions Described by the three Modules large scale

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #5 1-Nov-15 Contents of Industrial Package

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #6 1-Nov-15 Outline of Task 2+3 Mission Performance Simulator

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #7 1-Nov-15 Forward Scheme: Production of Synthetic Data Design of constellations Orbit Calculation –full mission: 4 years –mission start on January 1, 1997 (one solar cycle before anticipated launch) Calculation of synthetic magnetic and electric field data –magnetic field generator –electric field generator –auxiliary data

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #8 1-Nov-15 Orbit Design Constellation #1 Two pairs of satellites 450 and 550 km initial altitude 86.0° and 85.4° inclination lower satellites are close together separation a few hundred km upper satellites are at antipodal position 180° separation Different inclinations yields different drift rates 0.44 min/day differential drift rate corresponding to 90° separation after 27 months

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #9 1-Nov-15 Orbit Design Constellation #2 Pool of 6 (7) satellites Analysis of data from different combinations of up to 4 satellites Final name convention Swarm A (= 4) Swarm B (= 5) Swarm C (= 1) Swarm D (= 2)

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #10 1-Nov-15 Advantage of two satellites flying side-by-side Strong attenuation of large-scale magnetospheric terms Amplification of m»0 terms

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #11 1-Nov-15 Magnetic Field Gradient at 400 km altitude B r B  B  Magnetic field East-West Gradient of Magnetic field

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #12 1-Nov-15 Magnetic Field Generation

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #13 1-Nov-15 Improved Forward Scheme for Constellation #2 improved parameterization of magnetospheric sources: n=3, m=1 based on hour-by-hour analysis of world-wide distributed observatory data after removal of CM4 induced contributions are considered using a 3D conductivity model (oceans, sediments + deep-located mantle inhomogeneities) ”boosted” secular variation Noise added (based on CHAMP experience and Swarm specifications)

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #14 1-Nov-15 Power Spectral Density of Simulated Noise In January 2004 (production of data of constellation #2), the Phase A System Simulator models produces time series of magnetic field that are off by several nT. Therefore use of simple noise model, based on scaled CHAMP data  = (0.1, 0.07, 0.07) nT in agreement with Swarm performance requirements simple noise model Phase A noise model

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #15 1-Nov-15 Data Products For each constellation: 190 million satellite positions 10,950 data files 26.5 GB of data Production of synthetic data for one constellation takes a couple of weeks

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #16 1-Nov-15 In-flight Calibration and Alignment of the Vector Fluxgate Magnetometer (VFM) Calibration: Determination of the instrument response (including time and temperature drifts) by comparison with the readings of the Absolute Scalar Magnetometer (ASM) –methods developed for present single satellite missions Ørsted and CHAMP –Successful application to simulated Swarm data –exact timing of the instruments is essential (  t < 5 sec, cf. SRD) before in-flight calibration (using pre-flight values) after in-flight calibration

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #17 1-Nov-15 In-flight Calibration and Alignment of the Vector Fluxgate Magnetometer (VFM) Alignment: Determination of the rotation between the VFM and the star imager (ASC) –Single satellite methods work well provided that »the ”true” magnetic field is sufficiently well known »the difference  B has some special properties (distribution of  B in VFM frame) –Probably significantly relaxed conditions if constellation aspect (multi-satellite method) is considered –The mechanical stability of the VFM/ASC assembly (optical bench) is very essential! –Development of multi-satellite methods for in-flight alignment is needed

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #18 1-Nov-15 Various Approaches for Field Recovery Comprehensive Inversion (cf. presentation by T. J. Sabaka) Core Field and Secular Variation - Method 1 Core Field and Secular Variation - Method 2 Lithospheric Field Recovery - Method 1 (cf. presentation by H. Lühr) Lithospheric Field Recovery - Method 2 3-D Mantle conductivity - Method 1 (cf. presentation by N. Olsen) 3-D Mantle conductivity - Method 2

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #19 1-Nov-15 Test Plan Closed-loop-simulation: Test of the forward and inversion approaches using noise-free data –using data that only contain source fields for which we invert for Focus on field contributions that are main Swarm objectives –Core field and secular variation –Lithospheric field Test quantities: Difference between recovered and original model –Power spectrum of the model SH coefficients –Degree correlation  n of coefficients –Sensitivity matrix –Global Maps (e.g., of B r ) of the model difference Results: –successful recovery of the original model using clean, noise-free and noisy data Definition: noisy datadata containing S/C and payload noise noise-free datadata without S/C and payload noise clean datadata that only contain source contribution that is inverted for

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #20 1-Nov-15 Example of Closed-Loop Analysis Recovery of lithospheric field and of high-degree secular variation using data from 4 Swarm satellites and 88 observatories degree correlation  n > 0.9 Achieved by Comprehensive Inversion; details will be given by T.J. Sabaka original model recovered model difference

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #21 1-Nov-15 Results: Mission Performance Recovery of all relevant source contributions by Comprehensive Inversion (T. J. Sabaka) Recovery of the lithospheric field (H. Lühr) 3-D Conductivity of the Mantle (N. Olsen)

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #22 1-Nov-15 Comparison of Filter Method and CI CI superior at n<70, especially for terms m close to 0 Filter method is superior for n > 70

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #23 1-Nov-15 Mapping of 3D Mantle Conductivity Forward conductivity model contains near-surface conductors (oceans, sediments) local (small-scale) inhomogeneities (plumes, subduction zones) regional inhomogeneities (e.g., covering one plate) Attempt to map 3D mantle conductivity structure

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #24 1-Nov-15 Transfer Function: C-response C from local B z and B H, derived using a SHA Frequency dependence of C(  ) (or of other transfer functions) provides information on conductivity-depth structure  ( z ) Electromagnetic Induction: Attenuation of B with depth z:

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #25 1-Nov-15 Mapping of 3D Mantle Structure Real and imaginary part of the local C-response for a period of 7 days, reconstructed from time-series of spherical harmonic coefficients up to degree N. N = 5N = 9N = 45 (all terms)

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #26 1-Nov-15 Assessment: Core Field and Secular Variation Without Swarm: only ground station data With Swarm: local time coverage and improved quality Degree n Wavelength [km] Degree relative error % Degree correlation Total relative error %4

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #27 1-Nov-15 Assessment: Lithospheric Field A: 4-5 times more accurate than CHAMP Lower pair A+B (gradient) for detail Higher C separates external sources Combination A+B+C: optimal recovery up to n=130

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #28 1-Nov-15 Assessment: Lithospheric Field (cont.) B r at ground Degree n Wavelength [km] Degree relative error % Degree correlation Total relative error %7.9 degree n up to 60degree n up to 130 nT

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #29 1-Nov-15 True Model Swarm A+B+CSwarm A km Mission Performance: 3-D Mantle Conductivity Period 7 days Detection of inhomogenities of mantle conductivity is possible with Swarm constellation #2 Data from one satellite is sufficient to resolve inhomogeneities

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #30 1-Nov-15 Conclusions and Recommendations Full mission simulation performed for two constellations –Production of synthetic data of all relevant contributions to Earth’ smagnetic field –Recovery of the various field contributions using different approach Comprehensive Inversion was chosen as the primary approach Evaluation of Swarm constellations... and of the methods for field analysis Modified 3-satellite constellation (one pair of lower satellites, one higher satellite) fulfills the primary Swarm science objectives

Final Presentation, Swarm E2E study, June 18, 2004, ESTEC, nio #31 1-Nov-15 Recommendations for Future Studies Develop methods for pre-flight determination and test of VFM / ASC rotation Develop multi-satellite tools for in-flight alignment More sophisticated methods for utilizing the magnetic field gradient in geomagnetic field modelling Develop methods for imaging (mapping) of 3-D mantle inhomogeneities