|
|
 |
|
Dedications for Scribe Weekly Radio
|
Weather Satellites
It
must have been a breath-taking event for all the meteorologists in the
world. In the late evening of august 28 a new weather
satellite has been launched. And a special one; for this satellite
is the first of a new generation. The expectations are high pitched; it
should enhance observation of the planet's weather and long-term climate
from space; and a better forecasting and extreme-weather warnings will become
possible. Types of Satellites.
Geostationary
- these orbit at a height of 36,000 km above the equator, and 'hang' over
the same spot on the Earth's surface all the time. Meteosat, the geostationary
satellite operated by ESA
(a joint effort of European countries), provides pictures of the North
Atlantic and Europe every 30 minutes and images of the half globe every
hour. The images do not show objects of great detail because the satellite
is too far from the Earth.
Polar-orbiting
these pass over the Earth from pole to pole. The NOAA satellites,
currently operated by the USA, orbit at a height of 830 km and take 1 hour
and 42 minutes to complete each orbit. During this time, the Earth has
turned by about 25 degrees, so the satellite views a different part of the
surface each time it passes. As the orbit is much lower than that of the geostationary
satellites, the images provide detailed information about
the cloud structure. The UK receives images from a set of three passes,
twice a day, from each satellite. The first pass is over the eastern
Mediterranean, the second virtually over the UK, and the third over the
eastern Atlantic. One set of passes occurs during the day and the other at
night.
The new generation Meteosat
Meteosat Second Generation -1 (MSG-1) will be the first of three
geostationary satellites expected to maintain constant watch on our
weather from the same
MSG will have 12 spectral data channels instead of the current
Meteosat’s three. It will broadcast twice as often and with finer
resolution to give clearer images of rapidly developing weather systems
and local storm activity. Overall, MSG will transmit more than 20 times as
much information as Meteosat does today. Its greater number of channels
will make MSG more effective for monitoring the atmosphere, land and ocean
surfaces, useful for a wider variety of environmental purposes. The first MSG satellite has been developed by ESA and built by European
Industry (prime contractor Alcatel). EUMETSAT coordinated the user
requirements, developed the ground processing and satellite control
system, procured all launches and will operate the system for at least 12
years. The subsequent two satellites and their instruments will be funded
by EUMETSAT with ESA acting as the procurement agency with industry. Better warning-systems
Forecasting Several
European specialists have developed software for the MSG. They are called
SAF (Satellite Application Facilities). Some of this software is very
important to and useful for forecasting the weather for the coming 12
hours. (The "now casting" and "the very short range
casting"). There will be direct information about clouds for example:
the amount of cloud cover; type; temperature of the top, rain-clouds and
at larger scale also of airstreams and types.
Climate
research The SAF can
also be used for climate-research; so-called "climate monitoring SAF".
According to a spokesman of the Dutch Met office this new generation
meteosats are a very important break-through. For example the MSG has a
broadband radiation scanner. This can measure the radiation of warmth and
reflection of sunlight at the top of the atmosphere. Lots of information
is provided about the radiation components at certain locations of the
earth and during the day and the whole season. More knowledge about this
"radiation-balance" is of consequence for the climate
research. Another very
important instrument for climate-research is the "imager". (The
Spinning Enhanced Visible and Infrared Imager (SEVIRI)). This makes the
famous pictures we all know from the TV-forecasting. It shows the
developing and movements of the weather-systems. SEVIRI can localize
exactly where clouds are, far more exact than its forerunner. For Climate
researchers this is also of great importance, cause there's still not much
known about the influence of clouds on the climate. Data about the
thickness of clouds, the top temperature and the amounts of water-droplets
and ice crystals, are very important for validating forecasts and
climate-models. To summarize
the new generation of sats can provide huge amounts of data and
information not only for meteorologists but also for other disciplines.
Everything that has to do with the earth's surface can be scanned. For
example it's also valuable to localize the world vegetations, the Want to know more? Visit the following sites:
http://www.esa.int/export/esaMI/MSG/index.html
wijke@scribeweekly.com
|
position as its predecessors, 36,000 km above the
equator at 0º Longitude (over the Gulf of Guinea), for the next 12 years.
A fourth MSG is in the planning stage for continuation of the
service. 
The finer resolutions combined with the
higher transmission improve the opportunity to track the development of
local storm activity as thunderstorms. In particular the quality of
warnings for severe weather will increase.
density and the condition of it. And lots of other applications can be
developed in the future; but its still not to foresee how. Obvious is
however, that the new MSG will have a enormous impact on the use of
satellites and their observations. With the launch of MSG-1, aboard of the
Ariane-5, a new era has started.