Using 3D imagery from the Multi-angle Imaging SpectroRadiometer (MISR) instrument on the Terra satellite to show convective storms.
By Martin Setvák (CHMI)
On 18 December 2019, it will be 20 years since the launch of the NASA EOS Terra satellite. Since then, its MODIS data and images have become legendary. However, some of the satellite’s other instruments are less known to a broader public.
One of these is the MISR (Multi-angle Imaging SpectroRadiometer) instrument, which utilises nine cameras scanning at nine different angles, in three visible and one near IR band each (see scan concept). Standard pixel size is 275 m for the red band of all cameras, 275 m for all bands of the nadir-viewing camera (labeled AN), and 1.1 km for the other bands of the other cameras. The image swath is about 380 km, and the time lag between the first (DF) and last (DA) camera is about seven minutes.
In general, the main use of the instrument is to provide 3D information on clouds and aerosols, with a special focus on various plumes (both anthropogenic and natural – such as forest fires, volcanic eruptions, industrial plumes, etc.).
While the instrument has also been used for observations of tropical storms and hurricanes or typhoons, MISR observations of tops of convective storms, with all their presently known features and details, are rather scarce.
Here we show several examples of such 3D images (anaglyphs) of convective storms; to see these in 3D you will need red-blue (red-cyan) anaglyph (3D) glasses (Figure 2).
These images are a very good training resource to better illustrate the three dimensional structure of clouds.
All the images below were created in MINX (MISR INteractive eXplorer) software (download software), written by NASA’s JPL. The software bundle also contains detailed, very informative help files – not only about MISR data and their access, but also on various functions of the software itself and its applications (Note: the IDL 'runtime', which is used by this software, does NOT require installation of the IDL software itself). The option to create 3D red/blue anaglyphs can be found under the 'Animate Cameras', 'Task Menu' and 'Red/Blue 3D …' menus. All of the images were further enhanced in Adobe Photoshop, using Unsharp Mask and Color Saturation functions.
As the MISR cameras are tilted in the satellite’s track direction, the 3D effect can only be achieved in this direction, roughly from north to south. To prevent viewers needing to incline their heads, all the images were rotated 90° counter-clockwise by the MINX software, so the north is always on the left in these images.
All these anaglyph images were composed from the red bands at 275 m pixel size. All the MISR MI1B2E data used to create these 3D images were obtained from the NASA EarthData ASDC MISR Order and Customization Tool, using the MISR Browse Tool.
The images are best viewed at full resolution (click on images to magnify) or zoomed in, In general, it is also better to look at these 3D images in a darker environment, so that nothing disturbs the 3D effect. Plus it may take some time (up to about one minute) for your eyes to fully adjust to the 3D mode. As well as the four anaglyphs of convective storms, there is also one hurricane case and one case with details of jet-stream clouds.
Figure 3 shows convective storms above Texas, 02 May 2019, 17:23 UTC, see also the corresponding MODIS preview, showing the exact location of these storms.
Figure 4 shows an isolated convective storm above the eastern Pacific, south of Mexico, 13 May 2019, 17:20 UTC, see also the corresponding MODIS preview.
Figures 5a and 5b shows a line of convective storms above Arkansas and Louisiana on 16 June 2019, 17:00 UTC. Figure 3a shows these storms from the forward-tilted cameras BF and AF, while Figure 3b shows the storms from the back-tilted cameras AA and BA, see also the corresponding MODIS preview.
Figure 6 shows convective storm with a very nice outflow boundary, propagating westward, above Niger and Nigeria, on 6 September 2019, 10:17 UTC, see also the corresponding MODIS preview.
Figure 7 shows Hurricane Dorian and its eye, east of the US coast, on 5 September 2019, 16:05 UTC, see also the corresponding MODIS preview.
Figure 8 shows details of 'spikes' in clouds of a jet steam above the south-west Indian Ocean on 20 May 2019, 07:45 UTC, see also the corresponding MODIS preview.