The air mass product is an RGB composite based upon data from infrared and water vapor channels from Meteosat Second Generation (MSG). Originally designed and tuned to monitor the evolution of extra-tropical cyclones, in particular rapid cyclogenesis, jet streaks and PV (potential vorticity) anomalies by scientists at (EUMETSAT), it is also useful for tropical/subtropical applications. The product highlights differences between dry, tropical and cold air masses, as can be seen in the example below. This is accomplished by differencing the two water vapor channels (i.e., ch. 5 at 6.2 µmicro;m and ch. 6 at 7.3 µmicro;m) as depicted in the red colors, where red is associated with dryer air mass conditions locally, by Ozone differences by differencing ch. 8 at 9.7 µmicro;m and ch. 9 at 10.8 µmicro;m, where green indicates low Ozone & typically thus tropical air masses, and by using ch. 5 at 6.2 µmicro;m to indicate gross air mass temperature differences.
Figure 2: Air mass product example. Tropical air is displayed in green and red where the green regions have higher moisture content than the red regions. Mid-latitude air has a bluish color and areas or dark red show areas of subsidence and high ozone and PV.
The air mass product helps discriminate tropical air masses (i.e., moist and lower ozone) that are predominantly green, from subtropical air masses (i.e., dryer) that are depicted greenish red, and mid-latitude air masses, typically having more blue colors. For tropical applications it should be helpful in determining and tracking the origin of air parcels as they interact with tropical systems, and improved identification of shallow upper level features (cold lows and jets streaks). For more information on the interpretation of this product see (Kirkman, cited 2010). An annotated example is provided below.
Kirkman, J., cited 2010: Applications of Meteosat Second Generation (Meteosat-8), AIRMASS. [available on-line at http://oiswww.eumetsat.org/IPPS/html/bin/guides/msg_rgb_airmass.ppt]
Google Earth loops of GOES-E imagery over the CONUS are available at http://rammb.cira.colostate.edu/products/google_earth/
The RGB air mass product provides a simple decision aid tool to NHC forecasters by visually discriminating tropical air masses from subtropical air masses. For tropical applications it should be helpful in determining and tracking the origin of air parcels as they interact with tropical systems, and improved identification of shallow upper level features (cold lows and jets streaks). The current product is limited to the MSG sector.