Air mass combination
Combining different channels and their differences brings out more features in one image than it is possible for single channels.The "Airmass" RGB is a combination of 4 channels: (WV6.2-WV7.3,IR9.7-IR10.8,WV6.2)
The profile of brightness temperature difference of the water vapour channels depends on
- temperature and humidity profile
- satellite viewing angle
- cloud emissivity
The Water vapour channels and their difference give information about
- high and deep cloudiness
- very dry troposphere above the lowest layer
- humidity of middle troposphere
- humidity of high troposphere
- typical water vapour features like jet streams, wave features and deformation zones
The brightness temperature difference WV6.2-WV7.3 indicates:
- very small difference: very dry air
- small difference: moist layer at 700 or 200 hPa
- large difference: moist layer at 500 hPa
For further information see the MSG Interpretation Guide in Eumetsat web pages: http://oiswww.eumetsat.org/WEBOPS/msg_interpretation.
Look at the following image and put numbers on the corresponding features. First, click on one of the buttons to choose a number. Then, try to find the the correct area and click on it!
| 1 Dry area |
2 Deep Clouds |
3 Cloudy Area |
4 Humid air on middle/high levels |
5 Descending stratospheric air |
EUMeTrain, 2008