Monitoring weather and climate from space

Features

August 28, 2012

Ten years of Meteosat Second Generation

When the first Meteosat Second Generation satellite, Meteosat-8, was launched on 28 August 2002 it heralded a new era of discovery for meteorologists. It became fully operational at 0 degree longitude at the equator on 19 January 2004 and, in addition to providing weather information in much more detail, it provided information on phenomena which had never been considered before.

Meteosat-8 introduced a new instrument — [Internal link]SEVIRI (Spinning Enhanced Visible & Infrared Imager), the world’s best weather imager in geostationary orbit. This powerful instrument provided an improvement of image resolution in the visible spectrum, to 1 km from 2.5 km, and in the infrared, to 3 km from 5 km, and had multi-spectral imagery. This meant the satellite was suddenly showing features such as fog boundaries. It could be used to track elements such as volcanic ash — particularly useful during the [Internal link]Icelandic volcano eruptions of 2010 and 2011.

SEVIRI was able to supply, at intervals of 15 minutes (compared to 30 with the first generation), images of the earth disc observed by the satellite in 12 different visible and infrared wavelengths (a fourfold increase). By delivering data at twice the previous frequency, Meteosat-8 made it easier for meteorologists to detect high impact weather phenomena, such as thunderstorms.

The enrichment of the spectrum of observations was the main improvement, leading to major progress in nowcasting and numerical weather prediction. For the first time features such as night-time fog, dust and sulphur dioxide (SO2) could be monitored and tracked.

José Prieto, meteorologist and trainer at EUMETSAT, said: "The difference between MFG and MSG is like going from black and white TV to colour TV."

Detecting trace gases

Meteosat-8 has two sulphur dioxide (SO2) absorption bands in the infrared region. In June 2003 it was able to detect a sulphur smoke plume in Iraq.

On 25 June 2003, a fire broke out at the Al-Mishraq sulphur plant, about 25 km south of the city of Mosul, producing thick, toxic sulphur smoke. Affecting the cities of Qayyarah, Al Shurah and Makhmur, plus numerous villages, the smoke was a major environmental and health issue.
On this occasion the IR8.7 channel easily detected the plume. The SO2 cloud was depicted even better in the [Internal link]brightness temperature difference between the IR10.8 and the IR8.7 channels (AVI, 5 MB). During day-time, the IR8.7 channel was up to 21 K colder than the IR10.8 channel, due to the strong absorption of the radiation from the hot surface.

Volcanoes

Using SEVIRI’s 12 channels (at visible and infrared wavelengths), experts are now able to construct Red-Green-Blue (RGB) images which have proved, among other features, to be very useful for identifying volcanic ash clouds. The SEVIRI data also allow the retrieval of quantitative ash properties like the total column of ash.

On 24 November 2005 the Karthala volcano on the Indian Ocean island of Comoros started erupting, leading to the cancellation of a number of local flights. Clear skies over the area allowed Meteosat-8 to monitor the eruption from the beginning of the event.

[External link]Animation of the Karthala eruption 24/11/2005 17:00 UTC - 25/11/2005 23:00 UTC

Dust storms

On 13 May 2004, Meteosat-8 observed four major dust storms, over Lybia, Iraq, Saudi Arabia and Iran, plus several smaller ones over Sudan. The dust storms over Iraq and Saudi Arabia were related to strong north-westerly winds. The dust storms over Sudan appeared very clearly.

MSG with its capability to observe dust storms in a whole area at a frequency of 15 minutes, plays an essential role for aviation forecasting support, and also helps organisation like the United Nations to coordinate their humanitarian aid activities.

Night-time imagery — fog in South Africa (5 July 2003)

The introduction of Meteosat-8 infrared data meant that for the first time forecasters were able to see low cloud at night. Over the years that data has helped improve the accuracy of forecasts.

Dr Jochen Kerkmann, meteorologist and trainer at EUMETSAT said: "For me, the greatest difference Meteosat-8 has made to the previous generation is the improvement of night-time cloud detection and classification and also the better identification of cloud properties, such as cloud phase and cloud particle size."

South Africa’s largest international airport (Johannesburg International Airport) is situated just to the north-east of the city of Johannesburg and experiences frequent delays in flights due to the reduction in visibility caused by fog. In the past the weather forecasters were aware of this low stratus cloud and fog. However, the exact extend was not known during the night due to a sparse observational network and no visible satellite information. On 5 July 2003 forecasters were able to use the Meteosat-8 satellite imagery to track low stratus clouds moving in over the eastern high ground of South Africa.

Rapid Scanning Service

In 2005 Meteosat-8 was joined by Meteosat-9. While both satellites are operated  simultaneously, in 2008 Meteosat-8 was reallocated to providing the [Internal link]Rapid Scanning Service at 9.5°E. This service scans the northern third of the Meteosat disc every five minutes and provides a vital service, particularly for nowcasting high impact weather events like thunderstorms.

Other images from space

In 2008 Meteosat-8 produced rare satellite imagery of a meteorite exploding near the Earth. 2008 TC3 was a meteorite 2 to 5 meters (7 to 16 ft) in diameter and weighting 80 tonnes. It entered Earth's atmosphere on October 7, 2008 and exploded tens of kilometers above the ground causing a large fireball, which was, by chance, seen by Meteosat-8.

A number of Case Studies and Topical Images from Meteosat-8 can be found on our [Internal link]Image Library.

 

 

 

 

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