Satellite Analyses of Kelut Ash and SO2

We have been watching the recent eruption of Kelut volcano, Indonesia (see previous post) with interest, due to the large eruption cloud it produced and its impact on aviation in the local area.   The cloud was imaged by two of NASA’s infrared satellite-borne sensors: MODIS and AIRS which provide insights into the composition, lifetime and altitude of the cloud in the atmosphere. All data for the images below were supplied by NASA.

The following sequence of AIRS SO2 images show how the cloud dispersed and moved west over the Indian Ocean in the days following the eruption.

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Data from the CALIOP lidar instrument show that the bulk of the cloud was at 18 km altitude, with some species reaching up to 26 km.


The CALIOP lidar instrument gives an indication of the Kelut cloud altitude. Credit: S Carn.


Also evident in the CALIOP data are undulations on the surface of the cloud top.  The gravity waves can be  clearly seen in MODIS brightness temperature image below as concentric rings.


The plume topography can be inferred from the MODIS temperature data to better visualise the shape and structure of the cloud.  Click the image to view the animated gif.


MODIS images also provide information about the distribution and effective particle radius of the ash from the eruption.  Ash concentrations of up to 16 g/m2 were measured on the 14th February.