EUMETSAT - Product generation description


RGB

This section describes all products generated by means of RGB colour composition of 3 or more channels.

For more information, please check the MSG interpretation guide or refer to the following document:
Best practices for RGB compositing of multi-spectral imagery

 DUST

This colour composite has been designed to monitor the evolution of dust storms over deserts. The combination does allow however the further (24 hour) tracking of dust clouds as they spread over the sea. In practice, during the daytime the use of visible channels (in particular the HRV channel) is preferable for the tracking of dust over the sea.

Dust appears pink or magenta in this RGB combination. Dry land looks pale blue (daytime) to pale green (nighttime). Thick, high-level clouds have red-brown tones and thin high-level clouds appear very dark (nearly black). For more information, please refer to the following document:
Dust RGB colour interpretation

The RGB combination exploits the difference in emissivity of dust and desert surfaces seen in the IR channels listed below. In addition, and during daytime, it exploits the temperature difference between the hot desert surface and the cooler dust cloud.

The RGB composite is produced hourly using the following MSG channels/features: IR12.0-IR10.8 (on red), IR10.8-IR8.7 (on green) and IR10.8 (on blue).

 FOG / LOW CLOUDS (NIGHT-TIME)

This colour composite has been designed and tuned (by Prof. Daniel Rosenfeld from the Hebrew University of Jerusalem) to monitor the evolution of night-time fog / low stratus, which is usually difficult to detect in the MSG infra-red channels. When animation is applied to this RGB product, the formation of fog, for example, in river valleys can be monitored very closely. Other possible applications are the detection of fires, low-level moisture boundaries, thin Cirrus clouds and general cloud classification. It should be noted that this product is tuned for night-time conditions and is, therefore, not recommended for use during day-time.

At night, fog / low stratus appears light green in this RGB combination: the smaller the droplets the stronger the input from green. In contrast, the cloud-free land appears a pinkish colour, the thick high-level clouds have red tones or appear with a red-yellow speckled colour (indicating very cold clouds) and the thin high-level clouds appear very dark (dark blue). For more information, please refer to the following document:
Fog / Low clouds RGB colour interpretation

The RGB composite is produced hourly using the following MSG channels/features: IR12.0-IR10.8 (on red), IR10.8-IR3.9 (on green) and IR10.8 (on blue). In physical terms, this composite combines the following cloud information: cloud optical depth (on red), cloud phase and droplet size (on green) and cloud top temperature (on blue). In this way, it is consistent with the day-time microphysical RGB composite that uses the VIS0.8 channel (on red), the IR3.9 channel (on green) and the IR10.8 channel (on blue).

 AIRMASS

This colour composite has been designed and tuned using the results of a case study of rapid cyclogenesis (storm Gudrun over the North Atlantic and Baltic Sea on 7-9 January 2005). It combines the following three MSG features for the early detection of rapid cyclogenesis: the WV6.2 - WV7.3 Brightness Temperature Difference (BTD, on red), the IR9.7 - IR10.8 BTD (on green) and the WV6.2 channel (on blue) . All three features are strongly related to airmass characteristics in cloud-free areas and to the height of the cloud in cloudy areas. The WV6.2 channel shows the horizontal distribution of Upper Tropospheric Humidity (UTH). Typical features seen on the WV6.2 images include dry intrusions, deformation zones and jet streaks. The WV6.2 - WV7.3 BTD, which depends on the temperature and humidity profile, shows the distribution of moisture in the troposphere. Finally, the IR9.7 - IR10.8 BTD is related to the total ozone concentration and thus to the height of the tropopause. This particular feature is influenced by the satellite viewing angle (the BTD assumes large values for viewing angles above 80 degrees), which in turn affects the colours of the airmass RGB on the outer edges of the MSG image. In addition, in cloud-free areas the IR9.7 channel gets a strong signal from the earth surface, which leads to large BTDs over hot surfaces (e.g. the desert regions) during daytime. The above variants should be taken into account when interpreting the colours of the airmass RGB.

Combined in a RGB, the result is an image where high clouds appear in white colour, mid-level clouds in light ochre colour and cloud-frees areas in dark green colour (warm air mass with high tropopause) or blue colour (cold air mass with low tropopause). A particular feature of this RGB is that dry descending stratospheric air is marked by a reddish colour. For more information, please refer to the following document:
Airmass RGB colour interpretation

The RGB composite is produced hourly.

The full disc image is compressed into jpeg (70%, up to 250 KB/image) and has reduced spatial resolution. All the sectors are at full spatial resolution and compressed into jpeg (80%, up to 620 KB/image). They may take some time to download and the animations may appear slow initially.


Meteorological Products

This section describes all Meteorological Products generated.
A detailed description of Meteorological Products can be found here.
The Meteorological Products extraction facilities are part of the ground segments of the MTP and MSG satellites. They produce level 2 products on basis of Meteosat images in real-time or near-real-time.
 Multi-Sensor precipitation estimate (MPE) product
The MPE product consists of the rain rate in mm/hr for each first generation Meteosat image on original pixel resolution. The MPE product, updated in July 2006 to utilise data from Meteosat-8 and Meteosat-5, are produced in near-real time. The algorithm is based on the combination of passive microwave data from the SSM/I instrument on the US-DMSP satellites and images in the Meteosat IR-channel by a so-called blending technique.
The product is available in GRIB format for download.
A detailed description of the algorithm, its scientific background and its validation can be found in the following documents:
MPE - Introduction
MPE - Concept and Validation
MPE - Validation Status Report