|EOS Volcanology Plume Topography Studies|
Eruption Plumes (32K image)
Based on a photoclinometric model by L. Wilson, L. Glaze has developed an algorithm designed to derive plume top topography and height from MODIS (and/or AVHRR) images. The program, written in IDL, has been tested on several datasets. This AVHRR subscene shows Mount Redoubt (Alaska) in eruption on 18 December 1989. The vent is in the lower left corner of the image and the plume (white in this visible channel) is being blown to the east. The image is approximately 200 km across.
Plume Top Topography (262 K image)
This is a 3-D surface plot of the Mount Redoubt eruption plume shown above. The surface topography was derived from the visible AVHRR image using the photoclinometry approach. All axes units are in pixels; each pixel ~1.1 km across. A full discussion of the photoclinometry model and an analysis of these data are included in Glaze, L.S., L. Wilson, and P.J. Mouginis-Mark, "Volcanic eruption plume top topography and heights as determined from phooclinometric analysis of satellite data", J. Geophys. Res., 104, 2989-3001, 1999.
Popocatepetl Plume (45K image)
This is another AVHRR subscene showing a plume from the 10 March 1996 eruption of Popocatepetl, Mexico. The volcano is located near the top of the image and the fan shaped plume (light gray in this visible channel) is being blown to the south. This image was acquired around 7:00 in the morning (local time), so there is a very long shadow cast by the plume to the west.
Popo Plume Top Topography (256K image)
This is a preliminary 3-D surface plot of the Popocatepetl plume shown above. Again, the surface topography was derived using the photoclinometry algorithm. The display shown here has been rotated counterclockwise by about 30 degrees (in relation to the AVHRR image). All axes units are in pixels (analysis of pixel scale is not yet completed). The gentle slope rising to the western edge of the plume corresponds to the shadow area on the image. In this area, the algorithm is calculating the altitude of the plume above the ground, based on the elevation of the sun in the sky. Sharp peaks along the eastern edge of the plume beyond 60 pixels E-W (above 5 pixels elevation) are processing artifacts and should be ignored. We are currently working on refining the analysis for this plume. This analysis was conducted by Matt Peitersen.
Steam Plumes (222K image)
Many aspects of the way that eruption plumes grow and are dispersed into the atmosphere are poorly known. Before the plume top topography algorithm was functional, Lionel Wilson, Lori Glaze and Steve Baloga spent time studying smoke-stack plumes and other man-made phenomena to develop better algorithms that describe the phenomenon. Super-heated steam plumes, such as the ones seen here in southwest Iceland, form one such set of plumes that is useful for this type of analysis. Photo by Pete Mouginis-Mark.
Temperature Map of a Steam Plume (50K image)
This is a time-averaged map of the radiant temperature of an industrial steam plume. The minimum and maximum temperatures are accurate (relative to the assumed atmospheric temperature) to within a degree. Due to the process of averaging the video data, it is not possible to definitively assign temperatures to specific brightness levels. However, these temperatures can be used to give a general idea of the range of temperatures within the plume. Image provided by Lori Glaze.