HMI Active Region Tracks (Draft Version)

Michael Turmon, JPL, September 2011

The movies below are made with the current masks, hmi.Marmask_720s, which have been released on The masks use magnetogram information only (no intensity information). These test movies are one way to check on how well the current tracker parameters are working.

This page is complete and correct as of October 20, 2011. HARPs here are not final and will be updated prior to release.

Files Here

Current movies are in two halves for each month.

The movies show a lot of information. See this note on color coding and overlays for more.

Tag Size Extent Notes
Jan 2011 1 30M 2011/01/01+31d [No notes]
Jan 2011 2 21M
Feb 2011 1 34M 2011/02/01+28d [No notes]
Feb 2011 2 21M
Mar 2011 1 42M 2011/03/01+31d [No notes]
Mar 2011 2 31M
Apr 2011 1 53M 2011/04/01+30d [No notes]
Apr 2011 2 42M
May 2011 1 42M 2011/05/01+31d [No notes]
May 2011 2 40M
Jun 2011 1 40M 2011/06/01+30d [No notes]
Jun 2011 2 38M
Jul 2011 1 39M 2011/07/01+31d [No notes]
Jul 2011 2 41M
Aug 2011 1 41M 2011/08/01+31d Notes below
Aug 2011 2 43M
Sep 2011 1 52M 2011/09/01+22d Notes below
Sep 2011 2 24M

Times of Interest

These notes are about calibration issues and parameter tuning and are probably not interesting if you're seeking quick-look information on HARP evolution.

Notes on August movies

Cosmic Rays

Two apparent CRs: 2011/08/02 at 11:24, near the south pole, and 2011/08/04 at 06:48-07:00, near the north pole. You can verify this in the magnetograms: 2011/08/02 11:24 and 2011/08/04 06:48. The second also crosses over to the 07:00 image.

NOAA Comparison

The first movie shows good results by comparison with the NOAA data. The second is mostly good, but has two super-HARPs toward the end (red and blue, HARP numbers 3122 and 3090).

Super-HARP 3122

For an example of a large HARP, take a look at the late August red region (HARP 3122) on 2011/08/31 at 18:00. Here are the original magnetogram and flattened photogram.

The mask is based on magnetic activity around the ~200 Gauss regime. You can see a lot of spatially-extended magnetic activity, which causes "active region" to be indicated on the mask throughout the area of HARP 3122. There are three NOAA ARs in that area.

Looking at all that activity spread over the mask makes it clear why the corresponding movie frame (or the instantaneous patch map that the movie is based on) has such a large connected region (i.e., the HARP).

Just changing the grouping threshold used to form patches creates more problems than it solves. By the time the threshold is high enough to separate the super-HARP into separate HARPs, the small structures, even when magnetically significant, are no longer found. Changing the grouping kernel might be more effective, I have not experimented with that.

As another way to obtain more compact AR patches, you can threshold the photogram at 0.92 to crudely get spots; this loosely corresponds to thresholding the magnetogram around 350 Gauss. Here is an example of thresholding the Ic image to find spots: Ic < 0.92. The resulting regions are much more compact than the original mask. This makes this method of minimizing super-HARPs more promising than raising the grouping threshold.

Here is an alternative set of patches from a spot-like mask. The mask was derived from a field threshold of 350 Gauss. This shows good potential to shrink the patches around NOAA ARs, while still preserving HARPs due to small-but-strong magnetic features.

Notes on September movies

The most notable thing about the September movie is the large HARP, number 3219, that is well seen around 2011/09/17. The main lobe, which contains three NOAA ARs, seems magnetically connected. However, the "tail" near the equator seems undesirable. This region indicates a need for a parameter update to localize HARPs better. This kind of over-extension of HARPs is forseeable, because we originally chose parameters in a time of less activity.