MDI Active Region Tracks 1996-2009

These movies are from MDI "New Calibration" data from 1996.05-2009.09. The MDI team recalibrated its magnetograms in 2007, applying a spatially-varying correction. The new magnetograms are more accurate, but my earlier models for AR appearance are not calibrated for them.

The tracks shown here result from rescaling my earlier AR models by a mean value of 1.815 (gotten from examining the old vs. new magnetograms). Unlike the "old calibration" results we've looked at before, these tracks are a work in progress, and show some good tracking but also some artifacts.

The "old calibration" tracks are now online too.

Movie Layout

The images are 1024x1024; they may be cropped by the inline movie player in your browser. If this is getting in the way, download the movie and play it locally.

The disk is gray, and pixels labeled as "active" within the gray disk are black. The colored blobs represent the full content of different ARPs; small clumps of black pixels that are outside the ARP's are below-threshold.

Distractingly, the color of the blob surrounding a certain AR will change from frame to frame. This is an artifact of the coloring algorithm -- the blob is indeed being tracked.

The white bounding box surrounding the blob encircles all within-blob pixels (plus a context region of about 16 pixels). Sometimes a white bounding box will enclose two different-colored regions. This happens when, at a later frame, these two regions were merged. A small white square hangs inside the white box to remind us that this is a merged region.

New regions are shown with a white square hanging *outside * the bounding box.

The narrow horizontal bar across the top indicates time-to-previous-image. A bar across the whole top means 24 hours, halfway means 12 hours, etc.

Text Insets

All four corners of the movie have text insets.

Top left: frame number in overall image sequence.

Bottom left: Number of regions in this frame, time and date UTC, and MDI day and image number. The image number is 000[0-3], and corresponds to the synoptic Ic series.

Top right: For northern hemisphere, shows the region ID of the current region sets. A "^" next to the ID means it is the largest on the disk, and a "v" means it is the smallest. A "!" means it is new. A "+" means it will later be merged. The topmost region ID is the east-est in the northern hemisphere, and the bottom ID is the west-est.

Bottom right: Region list for southern hemisphere, in format just described.

Known Issues

The magnetic field calibration for ARs is not dialed in, so there are too many small ARs. The adjustment for 1-minute versus 5-minute integration time is not accurate right now -- some images are more noisy than others, and this is not accounted for. This miscalibration results in too many AR pixels due to noise, so some regions are erroneously merged.

There are cosmic ray strikes causing single-frame ARs. There are some photogram limb and scan-line artifacts which cause giant ARs. These are easy to filter using a combination of looking at SPIKECNT and manual exclusion.

Files Here

These files cover the whole time range. Where one leaves off, the next begins.

No. Size Starts at
1 7.5M 1996.05
2 22M 1998.10
3 24M 2000.06
4 25M 2001.11
5 14M 2003.05
6 11M 2005.01
7 9.4M 2006.09
8 5.2M 2008.06

Times of Interest

To call out a specific frame, I use MMMM.NNNN where MMMM is the MDI day number, and NNNN is the frame number.