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SUMMARY:Quantifying Systematic Biases in the Measurements of the Open Magn
 etic Flux
DTSTART;VALUE=DATE-TIME:20230509T124000Z
DTEND;VALUE=DATE-TIME:20230509T125500Z
DTSTAMP;VALUE=DATE-TIME:20240704T115653Z
UID:indico-contribution-307@meetings.aip.de
DESCRIPTION:Speakers: Ivan Milic (Leibniz Institute for Solar Physics (KIS
 ))\nOpen magnetic flux in the photosphere\, especially at the poles\, pres
 ents an important boundary condition for modeling the heliospheric field. 
 The field extrapolated from polar observations is roughly 50% lower than t
 he in-situ measurements (“open flux problem”). Here we present our eff
 orts to characterize biases in the open flux inference and that way explai
 n the discrepancy above. We use a state-of-the-art plage-like MURaM MHD si
 mulation of the solar photosphere to model polarized spectra of magnetical
 ly sensitive Fe I 630 nm doublet lines\, observed by the Hinode SOT/SP ins
 trument. We mimic the realistic observation at the disk center and the pol
 e by calculating emergent intensity\, applying instrumental effects  (spat
 ial and spectral PSF\, binning)\, and adding the photon noise. We then app
 ly different inversion codes built upon different physical assumptions to 
 these synthetic observations and compare results to the original simulatio
 n.\n\nAt the disk center\, a significant fraction (20\, down to 50%) of op
 en flux gets lost for the telescopes with apertures smaller than 1m. At th
 e pole\, the magnetic field disambiguation becomes a critical part: the as
 sumption of the radial field underestimates flux by around 30% while the i
 nclusion of the telescope PSF further exacerbates the problem. The more in
 -depth investigation that accounts for stray light still yields significan
 t discrepancies between the original and inferred intrinsic properties of 
 the magnetic field. These systematic errors in field diagnostics may be re
 duced by high-resolution or out-of-ecliptic observations.\n\nhttps://meeti
 ngs.aip.de/event/24/contributions/307/
LOCATION:Haus H\, Telegrafenberg
URL:https://meetings.aip.de/event/24/contributions/307/
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