Parallax-based Height Estimation of the Tonga Volcanic Plume
In this page, the height of the volcanic plume from Hunga Tonga-Hunga Ha‘apai on 2022-01-15 can be estimated from its parallax between the Himawari-8 and GOES-17 satellites.
- Although the two satellites observe the plume nearly simultaneously, small lags likely less than a minute are present. Thus, if you measure fast-moving features, its movement can contaminate the parallax and reduce the accuracy of the altitude estimation.
- For example, if a cloud is moving eastwards or westwards at 70 m/s and the two satellites observe it with a 60-second lag, its moves 4.2 km during the lag and contaminates the parallax, resulting in an altitude error a little below 2 km.
- Northward or southward movement of a cloud does not affect its altitude estimation because the latitude differences are ignored in the estimation.
- In the calculation of the parallax, the Earth is assumed to be an ellipsoid.
- Infrared images denote brightness temperatures (degC) in Band 13. The color scale is shown below.
Libraries and data sources
- A script by Don Cross is used for the geometry on ellipsoids.
- Math.js is used for matrix calculations.
- Leaflet is used to display satellite images.
- jQuery is used for the user interface.
- Original data of the satellite images is retrieved from the Open Data on AWS: Himawari-8, GOES-17.
- Satpy and Matplotlib are used to convert original satellite data to images.