COSMO-LC Data Analysis and Interpretation Magnetometry PRODUCTS and TOOLS

Transcription

1 COSMO-LC Data Analysis and Interpretation Magnetometry PRODUCTS and TOOLS Sarah Gibson Enrico Landi, Steven Tomczyk, Joan Burkepile, Roberto Casini Brandon Larson, Scott Sewell, Alfred de Wijn National Center for Atmospheric Research COSMO-PDR November 17, 2015

2 Why do we need COSMO? To observe the magneto thermal environment of the solar corona: the source of space weather If we ever want to predict Bz at the Earth, we need to be able to quantify the global coronal magnetic field Courtesy Merkin, Lyon, Wiltberger 2

3 COSMO-LC: Magnetically-sensitive measurements Coronal forbidden lines emission arises from both collisional excitation (~N 2 ) and resonance scattering from anisotropic radiation (~N) 2145_HMI_THERMO_MED_H2.dat White light PB pb Fe XIII 193 A Fe XIII A (Z_pos Rsun) (Y_pos Rsun) UNITS: 10^-8 Bsun LOG -2.4 Sensitive to Zeeman and saturated Hanle effects 3

4 COSMO-LC Level 1: Stokes I, Q, U, V ΘB = magnetic inclination along line of sight ΦB = magnetic azimuth in plane of sky ϑb = angle between B and solar local vertical Casini & Judge, 1999 σ (alignment) goes through zero and changes sign at van Vleck angle 54.74: o 1-3cos 2 (ϑb)=0 4

5 COSMO-LC Level 2 products: B LOS Quantitative measure of magnetic field strength Weighted integral along LOS (similar to pb) Lin et al., 2004 BLOS maps: plane of sky, Carrington, solar cycle MLSO white light (pb) 1.8 Solar Radii, Jan 1980 to Jan 2009 Courtesy Joan Burkepile 5

6 COSMO-LC Level 2 products: Azimuth Measures POS magnetic direction (with 90 degree flip when crosses V. Vleck angle) Quantifies expansion of flux tubes (significant to solar wind acceleration) CoMP I with polarization vectors CoMP Azimuth - black=radial; blue=clockwise tilt; red=counterclock tilt 6

7 COSMO-LC Level 2 products: Degree of polarization Example: coronal cavities, can be stable for multiple days, but ultimately CME precursors 7

8 COSMO-LC Level 2 products: Degree of polarization SXR Sigmoid NLFFF extrapolation with flux insertion Coronal cavities well-modeled by magnetic flux ropes Line-of-sight alignment minimizes projection issues Savcheva et al., 2012 Degree of polarization (+ azimuth) good diagnostic of magnetic topology Linear polarization lagomorph in coronal cavity Flux rope model forward-integrated for linear polarization cavity center Bak-Steslicka et al., 2013 CoMP P Bak-Steslicka et al., 2013 Model P 8

9 COSMO-LC Level 2 products: Degree of polarization AIA 193 CoMP degree of polarization (greyscale) and polarization vectors/ Pseudostreamers: characteristic signature in linear polarization Rachmeler et al.,

10 COSMO-LC Level 2 products: Doppler velocity CMEs and CME precursors Magnetic flux surfaces Tian et al., 2013 Bak-Steslicka et al.,

11 COSMO-LC Level 2 products: Waves Ubiquitous waves in Doppler velocity Products: phase speed, direction of propagation, damping Constrains BPOS and POS direction; heating/wind models Morton et al Tomczyk et al

12 COSMO-LC Tools: FORWARD SolarSoft IDL package Given plasma/magnetic fields synthesizes multi-λ observables Works with any analytic or numerical model Applies CLE code of Judge & Casini for visible/ir polarimetry Can generate synthetic COSMO Level-2 data PSI MAS White light pb 12

13 COSMO-LC Tools: FORWARD SolarSoft IDL package Given plasma/magnetic fields synthesizes multi-λ observables Works with any analytic or numerical model Applies CLE code of Judge & Casini for visible/ir polarimetry Can generate synthetic COSMO Level-2 data PSI MAS Fe XIII Intensity 13

14 COSMO-LC Tools: FORWARD SolarSoft IDL package Given plasma/magnetic fields synthesizes multi-λ observables Works with any analytic or numerical model Applies CLE code of Judge & Casini for visible/ir polarimetry Can generate synthetic COSMO Level-2 data PSI MAS Degree of polarization Fe XIII 14

15 COSMO-LC Tools: FORWARD SolarSoft IDL package Given plasma/magnetic fields synthesizes multi-λ observables Works with any analytic or numerical model Applies CLE code of Judge & Casini for visible/ir polarimetry Can generate synthetic COSMO Level-2 data PSI MAS Azimuth Fe XIII 15

16 COSMO-LC Tools: FORWARD SolarSoft IDL package Given plasma/magnetic fields synthesizes multi-λ observables Works with any analytic or numerical model Applies CLE code of Judge & Casini for visible/ir polarimetry Can generate synthetic COSMO Level-2 data PSI MAS B LOS Fe XIII 16

17 COSMO-LC Tools: FORWARD SolarSoft IDL package Given plasma/magnetic fields synthesizes multi-λ observables Works with any analytic or numerical model Applies CLE code of Judge & Casini for visible/ir polarimetry Can generate synthetic COSMO Level-2 data PSI MAS B LOS Fe XIV 17

18 COSMO-LC Tools: FORWARD SolarSoft IDL package Can add photon noise to telescope specifications CoMP COSMO 5 minute integration of circular polarization for Fe XIII 18

19 COSMO-LC Tools: FORWARD SolarSoft IDL package Can help validate/choose between models CoMP MAS PFSS 19

20 COSMO-LC Tools: FORWARD SolarSoft IDL package Dis$nguishing)between)models) Can help validate/choose between models L/I) V/I) Flux)rope) L/I) V/I) Sheared)arcade) L/I) V/I) Spheromak) Rachmeler)et)al.,)2013) 20

21 COSMO-LC Tools: From FORWARD to inverse Local source (e.g. loop) Using Fe XIII and nm data, analytic solution for vector B (Plowman 2014) Requires strong field/optimal orientation for full vector field recovery Non-local methods: tomography Methods for vector B inversion developed using circular and linear polarization measurements and solar rotation (Kramar et al., 2006; 2013) Assumes minimal evolution on solar time scales; apply solenoidal condition as regularization term; line-of-sight photospheric magnetic field required as boundary condition (initial condition, e.g. potential) 21

22 COSMO-LC Tools: From FORWARD to inverse Forward fitting Can vary model parameters and examine e.g. how currents affect linear polarization signal: forward fitting Line%of%sight,field, Linear,polariza4on,

23 COSMO-LC Tools: COSMO data incorporation methods MHD-model based approach to forward-fitting the global field (NCAR- CfA collaboration DOC-FM) Interpolated χ 2 surface Real χ 2 surface Initial guess global magnetic field Solve for best fit parameters (location, orientation, strength, height of ropes). Generate synthetic observables Add currents (flux- rope insertion) where don t match Model Data 23

24 COSMO-LC Tools: Community test-beds 3D representations of plasma and magnetic field (ground truth) Forward-modeled multi-wavelength synthetic observables For developing/testing inversion/data-incorporation techniques in advance of COSMO pb Stokes V (100MHz) EUV (211) Stokes V (10747 A) Quiescent filament flux rope with thermodynamics - Fan 24

25 COSMO-LC Tools: Community test-beds 3D representations of plasma and magnetic field (ground truth) Forward-modeled multi-wavelength synthetic observables For developing/testing inversion/data-incorporation techniques in advance of COSMO pb Global model with quiescent filaments (Mackay/Yeates/ Dalmasse) 25

26 COSMO-LC Tools: Community test-beds 3D representations of plasma and magnetic field (ground truth) Forward-modeled multi-wavelength synthetic observables For developing/testing inversion/data-incorporation techniques in advance of COSMO pb Active region simulation (Rempel) 26

27 Conclusions COSMO-LC will be an unprecedented resource for reconstructing the global coronal magnetic field BLOS maps (quantify coronal magnetic field strength) Azimuth and degree of polarization (POS direction/flux-tube expansion; magnetic topological diagnostic) Doppler velocity (magnetic flux surfaces; waves - phase speed, direction of propagation, damping) We are developing tools to maximize effectiveness of COSMO data FORWARD package: validate/choose between models Community test-beds: develop/test inversion/data-incorporation techniques pb 27