ASTER imagery of Ubinas Volcano, April 28 2013 at 15:03 UTC

Thanks to the NASA Earth Observatory website for posting the imagery online. http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=83583&src=nha

I downloaded the raw ASTER data and analyzed the imagery/data. Below is a composite of the two ASTER scenes to show the full extent of the plume.

RGB of ASTER channels 3N, 2 and 1.

Next I examined the TIR channels and performed a decorrelation stretch of the data. See below, again this was performed on the two mosaic-ed scenes. One can clearly see the ash plume, as this comes up as purple in the decorrelation stretch.

RGB view of the decorrelation stretch from channels 14, 12 and 10.

Next I displayed them in Google Earth to highlight the decorrelation stretch plume to the visible data.

Decorrelation stretch in Google Earth. Looking North with plume dispersing to the south.

Decorrelation stretch with polygon used to delineate the edge. Again, Looking North with plume dispersing to the south.

RGB imagery from 3N, 2 and 1, with the decorrelation stretch polygon. Looking North with plume dispersing to the south.

This analysis shows the usefulness of the decorrelation stretch and how coupled with the visible data can help to delineate the ash plume in the ASTER satellite data.