There are two data sets available for download: tracked data cubes and power spectra. The data are generated from HMI line-of-sight velocity data ("Dopplergrams"), and cover the period between 2010 May 8 and 2010 July 11 (Carrington 2096:150 to 2098:030). The specific dates were chosen to overlap with the final MDI dynamics campaign, but the period also benefits from low solar activity and B angle close to zero.
The data that we are providing for download are standard HMI data products, and documentation on these and other HMI products can be found on the Joint Science Operations Center (JSOC) website. Users familiar with JSOC's webtools can access the data directly (web access here for tracked data and power spectra). Direct links to .tar archives of data cubes are provided below.
The data are 16° by 16° cubes tracked at the Carrington rate and Postel-projected. The length of the tracked intervals is 1728 minutes at a cadence of 45 seconds. The map scale is 0.04 heliographic degrees per pixel. Each tracked region overlaps its neighbors by 50%. The coverage on the solar disk for each "frame" is shown below. The frames are repeated every 15° of Carrington rotation (1/24 of a rotation). Note that the final three frames (2098:060, 2098:045, and 2098:030) have a slightly different configuration at high latitudes due to the inceasing B angle.
Each .tar file collects tracked data cubes at the same Stonyhurst location for up to twelve consecutive tracks (180° of Carrington longitude). Both HTTP and FTP links are provided. The size of the .tar files (between 4Gb and 6Gb) was chosen as a tradeoff between unreasonably large individual file sizes and unreasonably large numbers of files to download. Those interested in downloading a small subset of the files can use the links below, but those needing more will likely find writing a fetch script much easier. For that purpose, we have text files with coordinates and urls here for HTTP and FTP downloads.
N.B. Only the central meridian and equatorial strips are currently available on this page. The remainder of the data are still being exported.
The data are apodized to unit weight within a circle of diameter 15° and Fourier transformed in space and time. The resulting power spectra are collected in the same way as the tracked data above and available for download. Text files with urls are available here for HTTP and FTP downloads.
For any inquiries regarding this data, please contact Charles Baldner (baldner at stanford dot edu).