163. A New Website Hosting HMI Time-Distance Pipeline Products

Contributed by Junwei Zhao. Posted on September 10, 2021

Junwei Zhao & Ruizhu Chen
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085

A new website was recently developed to host SDO/HMI’s time-distance pipeline products, including real-time far-side images, near-real-time full-disk subsurface flow fields, synoptic subsurface flow maps, long-term near-surface zonal and meridional flows, as well as the interior meridional circulation profile. These results or data cover the period starting from 2010 May 1, when the HMI was commissioned, till the present and are ongoing. The website is at: http://jsoc.stanford.edu/data/timed.

The website is divided into 4 sections. The first section shows the most recent far-side image and the most recent 30-day video of far-side images, and Figure 1 shows a snapshot of this section. The image and video shown on the webpage are updated every 12 hours and are about 19 hours behind the real time. The JPEG images for past results and the FITS files that were used to make the JPEG images are available from the JSOC page by clicking the links shown on this webpage. A document describing the results as well as caveats about the results is also available online, and we strongly recommend the data users to read this document before using the data.

Figure 1| Snapshot of the webpage showing the section of far-side images.

The second section of this webpage, as shown in Figure 2, shows our most recent near-full-disk subsurface flow map and synoptic subsurface flow map for the most recent Carrington rotation. The near-full-disk subsurface flow map, updated every 8 hours, is represented by the divergence of the flows instead of arrows, and the synoptic flow map, updated every 27 days, is plotted after data binning. The full-resolution data, both the most recent ones and all the past ones, are also available through JSOC link. Similarly, a document describing the data and caveats about the data is available online. Users are suggested to read the document before using the data.

Figure 2| Snapshot of the webpage showing the section of near-full-disk and synoptic subsurface flows.

The third section of this page, as shown in Figure 3, shows long-term evolution of the near-surface zonal and meridional flows. These results are obtained from the synoptic subsurface flows shown in Figure 2, and are updated every 27 days after the results for the most recent Carrington rotation are available. The zonal-flow results are after the uniform Carrington rotation rate is removed, and the meridional flow is after the systematic center-to-limb effect is removed to the best of our knowledge. The FITS files corresponding to these flow maps for different depths are available for downloading from this webpage. Once again, users are suggested to refer to the accompanying document before using the data.

Figure 3| Snapshot of the webpage showing the section of long-term evolution of subsurface zonal and meridional flows.

The fourth section of this page, as shown in Figure 4, is related to the Sun’s meridional-circulation profile. The shown file is our best available result using the HMI’s 2010-2017 observations, obtained after applying a comprehensive method to remove the systematic center-to-limb effect and the surface magnetic-field effect. However, users need to be cautioned that this is an ongoing research topic, and the Sun’s meridional-circulation profile is not yet very clear to us for the time being.

Figure 4| Snapshot of the webpage showing the section of the Sun’s interior meridional circulation.

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