The Influence of Farside Data

Live Prediction Including PHI/FDT Farside Data(K-Corona Total Brightness)
Alternate Model With HMI Data Only(K-Corona Total Brightness)
Colorized Overlay of Both Models(Green: With Farside Data, Magenta: Without)
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Thanks to the help of the Solar Orbiter PHI team, this year’s eclipse prediction represents the first time our group has been able to include near-real-time magnetic field observations from off of the Sun-Earth line. As described on the Solar Orbiter page, this allows us to ingest much more up-to-date magnetic field observations beneath what will be the East limb (left-side) of the corona during totality.

Scientifically, this provides a unique opportunity to examine the effect of including fresh farside data into a live prediction model. To test this, beginning on August 1st, when the first batch of PHI data was ingested into the model, we also started a second coronal calculation where we do not assimilate PHI data, and instead proceed only with SDO/HMI measurements from the Sun-Earth line.

The top row of movies shows the difference between the two simulations for the predicted shape and structure of the corona in white light. The left panel is the Live Prediction featured throughout these pages, which includes farside PHI data. The middle panel is the “No Farside” simulation which does not. The right panel is an attempt to visually illustrate the morphological differences between the two simulations. To do so, the left image for the Live Prediction is rendered in green, while the middle image for the No Farside model is rendered in magenta. When the two models precisely agree, the structure will appear colorless (grey to white), whereas where they do not overlap you see one color or the other. As expected, the West limb (right side) is far more similar between the two calculations than the East limb (left side), where the farside PHI data assimilation occurred. Because both simulations are time-dependently driven separately starting at 4 UT on August 1st, sometimes they appear more different than others because of the inherent dynamics (e.g. a CME in one and not the other).

The bottom row of movies shows the two different HipFT model realizations of the surface magnetic field. Left is the simulation with PHI data, where one periodically sees a black contour appear when PHI data is being assimilated from the Solar Orbiter vantage point. The right movie is the “No Farside” or HMI only run. Outside the assimilation window the models look extremely similar as expected. Inside the assimilation window we see some differences in places where new flux has emerged. In this case the amount of new farside emergence was not extremely significant between August 1st and August 9th, but there was new emergence right around 135∘^\circ Carrington Longitude and -10∘^\circ latitude. Amazingly, this will be right beneath the East limb during the eclipse!

HipFT Model, Including Farside PHI/FDT Data(SDO assimilation region plus later SO view and assimilated regions are indicated)
HipFT Model, With HMI Data Only(SDO assimilation region plus later SO view and assimilated regions are indicated)
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NOTE: This page shows the result of two simulations. The final time of the model states on this page may not exactly match the rest of the pages if both simulations hav not made it to the same place yet.

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ACKNOWLEDGEMENTS

This research is funded by NASA and NSF. We are grateful to Instituto de Astrofísica de Canarias (IAC) for providing a dedicated allocation at the LaPalma supercomputer and proud to support the North African Telescope Eclipse (NATE) project, led by IAC. We also acknowledge dedicated resources from the ACCESS program and Expanse supercomputer at the San Diego Supercomputer Center (SDSC). We thank NASA's Advanced Supercomputing Division (NAS) for allocations on the Athena supercomputer that enabled many of the visualizations on this page to be produced rapidly in real-time. We also thank the SDO/HMI team of the Solar Physics Group at Stanford University for their support in providing timely access to HMI vector magnetograph data. Lastly, we are particularly excited to work with the Solar Orbiter PHI team, to conduct the farside assimilation experiment in near-real-time.