Astronomy and Astrophysics – Astrophysics
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufmsh12a..02h&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #SH12A-02
Astronomy and Astrophysics
Astrophysics
[7511] Solar Physics, Astrophysics, And Astronomy / Coronal Holes, [7524] Solar Physics, Astrophysics, And Astronomy / Magnetic Fields, [7924] Space Weather / Forecasting, [7959] Space Weather / Models
Scientific paper
Observed global solar photospheric magnetic field distribution maps, of high quality and cadence, are critical for coronal and heliospheric models to forecast and estimate the severity of geoeffective space weather events. Until STEREO-like observations of the solar magnetic field are available on the solar far-side, only the Earth-side of the solar surface is measured without large temporal gaps. This results in global maps which include data more than 13 days old, since the solar rotational period relative to Earth is approximately 27 days. The boundaries between old and new observations typically lead to large discontinuities that result in monopole signals. To avoid these large discontinuities, along with the lack of or poor polar measurements which can also introduce artificial monopoles, we have developed the ADAPT (Air Force Data Assimilative Photospheric flux Transport) model. ADAPT incorporates data assimilation using an Ensemble Least Squares (EnLS) estimation method with photospheric magnetic flux transport. The transport model is a modified version of the Worden and Harvey (WH) model that evolves the solar magnetic flux by incorporating rotational, meridional, and super-granular diffusive transport processes during periods that lack observations for a given solar region. The modified model utilizes an ensemble of model realizations using different model parameters. In this presentation, the methodology for incorporating solar magnetic far-side data, inferred from helioseismology, in the ADAPT model will be discussed. This will include our approach for representing the nominal distribution and morphology of the far-side active region polarity (e.g., Hale rule) and orientation (e.g., Joy's rule) within the ADAPT ensemble. For example, though any single choice for the far-side flux distribution and organization is expected to be amiss at best, a distribution of morphologies within the estimated far-side signal area can be generated using the ADAPT ensemble of global maps to represent nominal active region characteristics. In addition, the need for realistic error estimations of the far-side field strength and area to better estimate the model uncertainties will be discussed. Besides providing an improved estimate of the global magnetic field, the far-side signal allows for a more accurate representation of the uncertainty within the model ensemble for more rapid data assimilation once the region is observed. Preliminary model comparison between ADAPT maps with and without far-side data for forecast parameters (e.g., the solar 10.7 cm radio flux) will be presented. This work is supported by a grant from the Air Force Office of Scientific Research (AFOSR) and by the AFRL Space Weather Forecasting Laboratory (SWFL).
Arge Charles Nickolos
Godinez Humberto C.
González Hernández Irene
Henney Carl John
Koller Josef
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