Snowfall
The main application of the Snow RGB (Red, Green, Blue) is the detection of fog / low clouds and snow during day-time. In this color scheme snow appears red because of the strong absorption in the NIR1.6 and IR3.9 channels (no green and blue), while fog / low clouds appear whitish. Small particle ice cloud appears orange, while large particle ice cloud appears with greater red component. Snow on the ground appears as full red, because its grains are usually much larger than cloud ice particles. From 1 June 2022, Meteosat-9 at 45.5° E is the prime satellite for the IODC service, replacing Meteosat-8 (located at 41.5° E while in operation).
Airmass
The Airmass product is an RGB (Red, Green, Blue) composite based upon data from infrared and water vapour channels from the SEVIRI instrument. It is designed and tuned to monitor the distribution of different air masses and evolution of cyclones, in particular rapid cyclogenesis, jet streaks and PV (potential vorticity) anomalies. Due to the incorporation of the water vapour and ozone channels, its usage at highest satellite viewing angles is limited. The Airmass RGB is composed from data from a combination of the SEVIRI WV6.2, WV7.3, IR9.7 and IR10.8 channels. From 1 June 2022, Meteosat-9 at 45.5° E is the prime satellite for the IODC service, replacing Meteosat-8 (located at 41.5° E while in operation).
Precipitation rate
Instantaneous precipitation maps over IODC area generated combining geostationary (GEO) IR images from operational geostationary satellites 'calibrated' by precipitation measurements from MW images on Low Earth Orbit (LEO) satellites, processed soon after each acquisition of a new image from GEO. The blending algorithm ('Rapid Update’) generates precipitation estimates combining the equivalent blackbody temperatures (TBB) at 10.8 μm with rain rates from all available Passive MW measurements. A separate treatment is performed for convective precipitation: the morphologic information and the enhancement of precipitation estimate is done by the use of NEFODINA software.
Day Microphysics
The Day Microphysics RGB (Red, Green, Blue) was inherited from Rosenfeld and Lensky (1998): the VIS0.8 reflectance in red approximates the cloud optical depth and amount of cloud water and ice; the IR3.9 solar reflectance in green is a qualitative measure for cloud particle size and phase, and the IR10.8 brightness temperature modulates the blue. This color scheme is useful for cloud analysis, convection, fog, snow, and fires. In this colour scheme water clouds that do not precipitate appear white because cloud drops are small, whereas large drops that are typical to precipitating clouds appear pink, because of the low reflectance at IR3.9 manifested as low green. Supercooled water clouds appear more yellow, because the lower temperature that modulate the blue component. Cold and thick clouds with tops composed of large ice particles, e.g., Cb tops, appear red. Optically thick clouds with small ice particles near their tops appear orange. From 1 June 2022, Meteosat-9 at 45.5° E is the prime satellite for the IODC service, replacing Meteosat-8 (located at 41.5° E while in operation).